CN105543678B - High intensity non-annealed steel for fastener wire rod of a kind of boracic and preparation method thereof - Google Patents

Abstract

The invention discloses high intensity non-annealed steel for fastener wire rod of a kind of boracic and preparation method thereof, the high intensity non-annealed steel for fastener wire rod of described boracic has the chemical composition of following weight percents：C 0.20～0.24 wt%, Si≤0.50～0.70wt% of 0.04wt%, Mn, 0.25～0.35wt% of Cr, 0.035～0.055wt% of Ti, 0.035～0.055wt% of Als, 0.0045～0.0060wt% of B, S≤0.004wt%, P≤0.012wt%, O≤0.0015wt%, H≤0.00015wt%, remaining is Fe and inevitable impurity.Preparation method includes molten iron pretreatment desulfurizing, smelting molten steel, deoxidation alloying, molten steel LF stove refines, molten steel VD stove vacuum refinings, molten steel casting, heating steel billet, controlled rolling and controlled cooling step；The boracic high-intensity fasteners of present invention production are high with steel wire rod cleanliness factor, field trash is few, with good quenching degree, suitable intensity and hardness and excellent plasticity and toughness and cold-heading forge ability, not needing spheroidizing to process can direct 10.9 grades of high-level standard component of cold upset forming process for producing, manufacturing procedure and steel consumption are reduced, production cost is reduced.

Description

High intensity non-annealed steel for fastener wire rod of a kind of boracic and preparation method thereof

Technical field

The invention belongs to field of material technology, and in particular to a kind of high intensity non-annealed steel for fastener wire rod of boracic and its Preparation method.

Background technology

Steel for fastener is to produce the higher steel for standard part of interchangeability using cold-heading extrusion forming process.Steel for fastener Metal Forming molding is utilized at normal temperatures, and material inside organization is tight, the mechanical property of product is good, rapidoprint loss Less, productivity effect height, low energy expenditure, product size high precision, surface smoothness are good, be widely used in cold upset forming bolt, The production of all kinds of securing members such as nut, screw, rivet and bearing pin and spare and accessory parts.

In recent years, with the product restructuring of Investment in fastener industry, securing member from low-intensity to high intensity non-annealed development, From high energy consumption to resource-conserving, development has become inexorable trend.Boracic 10B21 cold-forging steels have good plasticity and cold-heading Can, wire rod original hardness is low, can shorten or exempt from annealing process, and cold heading cracking rate is low, has intensity after conditioned heat treatment It is high, the advantages of quenching degree is good, it has also become each steel for fastener enterprise manufactures the major demands product of high-intensity fasteners.Current state Basically by converter+LF stoves refine+continuous casting+high speed wire rolling technique productions, in steel, gas contains interior boracic 10B21 the cold heading steels Amount and field trash are of a relatively high, oxygen content>25ppm, hydrogen content>2ppm, non-metallic inclusion are mostly 0.5-1.0 levels, additionally, The microscopic structure proportioning of steel is not up to optimization, causes the plasticity and toughness of steel relatively low, and its cold-formed and deformability is limited, disk 1/4 cold upsetting qualification rate of bar is low, constrains application of the product in 10.9 grades of high-level standard components.

The patent and paper studies report of existing high-intensity fasteners steel domestic at present, but the plasticity and toughness and section receipts of steel Shrinkage is relatively low, and product is served only for the production of 8.8 grade high-strength bolts mostly.Such as the patent of Iron And Steel Co., Ltd of Shanxi Xintai City application " the high-intensity fasteners steel and its production method of a kind of titaniferous and boron hot rolling soft ", the chemical composition of steel is：C 0.19- 0.38wt%, Si≤0.30wt%, Mn 0.50-1.48wt%, P≤0.025wt%, S≤0.015wt%, Ti≤0.050wt%, B≤ 0.0045wt%, using the technique productions such as converter smelting, LF stove refines, continuous casting, high speed wire rolling, wire rod hardness 80-90HRB, section Shrinkage factor only 48%, microscopic structure have a small amount of bainite, and product is used to manufacture 8.8 grades of securing members；Baoshan Iron ＆ Steel Co., Ltd The patent " the high-intensity fasteners cold pier steel of Micro Alloying two-phase and its manufacture method " of application, the chemical composition of steel is：C 0.06- 0.15wt%, Si 0.60-0.90wt%, Mn 1.40-2.00wt%, P≤0.025wt%, S≤0.025wt%, Al≤0.040wt%, Using technique productions such as converter (or electric furnace) smelting, LF stove refines, continuous casting (or molding), high speed wire rollings, wire rod metallographic structure is 15 ~ 30% martensites (or containing a small amount of bainite)+70 ~ 85% ferritic structure, mechanical property Rm >=550MPa, percentage elongation A 16- 23%, contraction percentage of area Z 27-66%, product are used to produce 8.8 grade high-strength fasteners；Jiangsu Sha Gang groups Huaihe River steel special steel is limited A kind of patent " high-strength corrosion-resisting steel for fastener " of company's application, the chemical composition of steel is：C 0.14-0.17wt%, Si 0.17-0.24wt%, Mn 0.50-0.70wt%, Cr 0.85-0.95wt%, P≤0.020wt%, S≤0.020wt%, using converter Smelting, LF stove refines, continuous casting, high speed wire rolling technique productions, the tensile strength Rm 490-520MPa of steel, elongation percentage 30%；Jiangsu The sweet papers " exploitation of boron-containing cold heading steel 10B21 gren rods " for hoping benefit et al. deliver of Sha Gang, the chemical composition of steel is：C 0.18-0.23wt%, Si≤0.10wt%, Mn 0.60-0.90wt%, P≤0.035wt%, S≤0.030wt%, B 0.0010- 0.0030wt%, Al 0.020-0.035wt%, using electric furnace smelting, LF stove refines, continuous casting, high line controlled rolling and controlled cooling technique productions, Wire rod tensile strength Rm 505-550MPa, percentage elongation A 25-30%, contraction percentage of area Z 64-70%, product are used to produce 8.8 grades High-intensity fasteners.The plasticity and toughness and machining deformation ability of existing boracic high-intensity fasteners steel are not met by market to be needed Ask, therefore, develop a kind of product that can be solved the above problems and be very important.

The content of the invention

The first object of the present invention is to provide a kind of boracic high intensity non-annealed steel for fastener wire rod；Second purpose exists In the preparation method for providing the described high intensity non-annealed steel for fastener wire rod of boracic.

The first object of the present invention is achieved in that the described high intensity non-annealed steel for fastener wire rod of boracic has The chemical composition of following weight percents：C 0.20~0.24wt%、Si≤0.04wt%、Mn 0.50~0.70wt%、Cr 0.25~ 0.35wt%、Ti 0.035~0.055wt%、Als 0.035~0.055wt%、B 0.0045~0.0060wt%、 S≤0.004wt%、 P≤0.012wt%, O≤0.0015wt%, H≤0.00015wt%, remaining is Fe and inevitable impurity.

The second object of the present invention is achieved in that and comprises the following steps：

A, molten iron pretreatment desulfurizing：By 4.5 ~ 5.0wt% of chemical composition C, 0.30 ~ 0.50wt% of Si, Mn 0.25 ~ 0.090 ~ 0.110wt% of 0.50wt%, P, S≤0.020wt%, remaining is the blast-melted fortune of Fe and inevitable impurity Desulfurization process are carried out to KR methods molten iron preprocessing unit, stirring-head insertion depth is controlled to 2200 ~ 2400mm, by 15.0 ~ 17.0 kg/t_SteelAmount, add routine CaO matter desulfurizing agent carry out desulfurization process, mixing time is controlled to 8 minutes；Stirring is carried out after terminating Take off rear slag operation, it is ensured that in ladle molten iron face it is exposed >=4/5, scratch clean desulfurization slag；After pretreatment, hot metal composition is controlled to：C 4.5~ 0.30 ~ 0.50wt% of 4.8wt%, Si, 0.25 ~ 0.50wt% of Mn, 0.090 ~ 0.110wt% of P, S≤0.004wt%, remaining is Fe And inevitable impurity；

B, smelting molten steel：By chemical composition C 4.5-4.8wt%, Si 0.30-0.50wt%, Mn 0.25-0.50wt%, P 0.090-0.110wt%, S≤0.004wt%, remaining be Fe and inevitable impurity step A pretreatment depth desulphurised hot metal, Chemical composition C 0.16-0.25wt%, Si 0.12-0.25wt%, Mn 0.45-0.70wt%, P 0.015-0.030wt%, S 0.018-0.035wt%, remaining is the high-quality steel scrap and chemical composition C 3.2-3.4wt%, Si of Fe and inevitable impurity 0.30-0.50wt%, Mn 0.30-0.50wt%, P 0.070-0.090wt%, S 0.020-0.035wt%, remaining is Fe and can not During the low-phosphorous sulphur pig iron of the impurity for avoiding adds LD converter, conventional top bottom blowing is carried out, respectively by 40.0 ~ 45.0kg/ t_Steel、18.0~22.0kg/t_Steel、3.0~5.0kg/t_SteelAddition, add Calx, light dolomite, magnesite ball slag making, control is eventually Point carbon content >=0.08wt%, tapping temperature≤1640 DEG C；Active lime is added to carry out wash heat, Calx to ladle bottom before tapping Addition is 2.5kg/t_Steel；Using whole bottom argon blowing technology during tapping, argon flow amount is controlled to 20 ~ 35NL/min；

C, deoxidation alloying：Step B is smelted the molten steel tapping for finishing, when the molten steel amount in ladle is more than 1/4, is pressed Row deoxidation alloying order：Ferro-aluminum → high carbon ferro-chrome → high carbon ferromanganese, adds following material successively in ladle：By 2.2 ~ 3.0kg/t_SteelAmount, add following mass ratio ferro-aluminum：Al 70.5wt%, remaining is Fe and inevitable impurity；Press 4.1~5.8kg/t_SteelAmount, add following mass ratio high carbon ferro-chrome：Cr 56.7wt%, C 7.2wt%, remaining is Fe and can not The impurity for avoiding；By 5.4 ~ 8.1kg/t_SteelAmount, add following mass ratio high carbon ferromanganese：Mn 75.6wt%, C 6.7wt%, Remaining is Fe and inevitable impurity；Above-mentioned alloy is added when ladle molten steel amount reaches 4/5；After tapping is finished, by steel Water hangs delivers to LF stove refining procedures；

D, molten steel LF stove refines：Step C tapping is finished into molten steel it is hung to LF stove refine stations and connect argon gas band, opens argon Using the little argon amount Argon 2 minutes of 20 ~ 30NL/min, then bottom electrode adopts 7 ~ 9 grades of sluggings of gear；After being powered 3 minutes, lift electricity Slugging situation in pole observation stove, afterwards thermometric, sampling；If slag condition is diluter, 4.0 ~ 6.0kg/t of Calx is added_Steel, it is subsequently adding carbide 0.5kg/t_SteelResidue adjustment, controls basicity of slag for 5.5 ~ 7.0；According to steel sample analysis result, alloy, aluminum shot adjustment molten steel component are added, Control molten steel oxygen activity≤5ppm；It is 40 ~ 50NL/min suitably to increase argon flow amount afterwards, by 1.9 ~ 2.9kg/t_SteelAmount, plus Enter the ferrotianium of following mass ratio：Ti 33.5wt%, remaining is Fe and inevitable impurity, soft blow argon 3 minutes；Press afterwards 0.3~0.4kg/t_SteelAmount, add following mass ratio ferro-boron：B 21.5wt%, remaining is Fe and inevitable impurity, soft Argon 2 minutes；Afterwards liquid steel temperature is heated to wire feeding process is carried out after 1665 ~ 1675 DEG C, feeding has following mass ratio Aluminum calcium line：Ca 57.2wt%, Al 36.5wt%, remaining be Fe and inevitable impurity, wire-feeding velocity is 2.5m/s, line feeding Measure as 150m；Line feeding terminates to adopt flow to carry out molten steel for the little argon amount of 20 ~ 30NL/min soft blow argon, and the soft blow time is 2 Minute, add conventional big bag molten steel covering agent, addition to be controlled to 1.0kg/t afterwards_Steel, molten steel is hung to into VD stove vacuum fines then Refining station；

E, molten steel VD stove vacuum refinings：D step molten steel is hung to into VD vacuum refining furnace rear, Argon pipe is connected, argon is opened Using the little argon amount Argon 2 minutes of 20 ~ 30NL/min, oxygen is determined to molten steel afterwards and determines hydrogen, while thermometric sampling；After sampling is finished, Vacuum container cover car is opened to working position, close vacuum container cover, carry out evacuation, when vacuum is evacuated to 60Pa, proceed by fidelity empty Degassing process, while carrying out BOTTOM ARGON BLOWING process, argon flow amount is controlled to 40 ~ 60NL/min, the molten steel under the conditions of vacuum 60Pa 15 minutes degassing process time；Fruit storage closes vacuum main valve after finishing, lift cover, and liquid steel sampling is determined with oxygen is determined Hydrogen；Carry out little argon amount soft blow argon afterwards to process to molten steel, argon flow amount is 20 ~ 30NL/min, and soft argon blowing time is 2 minutes； After molten steel soft blow argon terminates, conventional big bag molten steel covering agent, addition is added to be controlled to 1.0kg/t_Steel, then molten steel is hung to and is poured Foundry work position；

F, molten steel casting：It it is 1525 ~ 1535 DEG C in tundish temperature, pulling rate is 2.1 ~ 2.3m/min, and Water Rate for Secondary Cooling Water is 1.1 ~ 1.3L/kg, M-EMS Current intensity be 300A, running frequency be 2.5Hz under conditions of, using the straight arcs of R9m The molten steel whole process protection of E steps is casting continuously to form the stream small billet casting machine of 5 machine of shape continuous straightening 5 steel billet of section 150mm × 150mm；

G, heating steel billet：F-step steel billet is sent in heating furnace of the soaking zone furnace temperature for 1080 ~ 1120 DEG C, heating 50 ~ 70 Minute, steel billet tapping temperature is 940 ~ 980 DEG C, goes out squama by water under high pressure, pushes to 5 base positions before inlet of rolling mill and treat that warm area is carried out The natural cooling of 3 ~ 5 minutes, finally enters mill milling with 900 ~ 920 DEG C of start rolling temperature；

H, controlled rolling and controlled cooling：The high-speed rod-rolling mill that the steel billet of G steps sends into 28 frames is rolled, in speed is Under the rolling condition of 0.15 ~ 0.25m/s, 6 passages of roughing；Afterwards under rolling condition of the speed for 10.0 ~ 15.0m/s, in Roll 12 passages；Before carrying out finish rolling afterwards, pre- water-cooled control is cold, is 120 ~ 150m in cooling water inflow³Cold 2 ~ 3 seconds are controlled under/h；It Afterwards final rolling temperature be 840 ~ 860 DEG C, speed for 20 ~ 65m/s rolling condition under, 5 ~ 10 passages of finish rolling；Afterwards in temperature For 820 ~ 835 DEG C, speed is spinning under conditions of 20 ~ 65m/s；After spinning, wire rod carries out " delay " into Stanermo wind-cooling linear Type control cooling, i.e. Slow cooling；Blower fan Close All when Stanermo wind-cooling linear control is cold, opens Cover lid, roller table speed are controlled to 0.25 ~ 0.45m/s；After the air-cooled end of stelmor, collection volume temperature control is 550 ~ 600 DEG C, it Natural air cooling to room temperature will be coiled afterwards and obtains the high intensity non-annealed steel for fastener wire rod of boracic, with following weight percents Chemical composition：C 0.20~0.24wt%、Si≤0.04wt%、Mn 0.50~0.70wt%、Cr 0.25~0.35wt%、Ti 0.035~0.055wt%、Als 0.035~0.055wt%、B 0.0045~0.0060wt%、S≤0.004wt%、P≤0.012wt%、 O≤0.0015wt%, H≤0.00015wt%, remaining is Fe and inevitable impurity, the technologic mechanicses performance having and aobvious Micro-assembly robot and field trash are shown in Table 1, table 2：

1 boracic high-intensity fasteners of table steel coil rod technologic mechanicses performance

Table 2 boracic high-intensity fasteners steel coil rod microscopic structure and field trash

, apparently higher than existing production technology, in steel, hazardous elements S, P content are low, P for the wire rod cleanliness factor produced by the present invention ≤ 0.012wt%, S≤0.005wt%, oxygen content≤0.0015wt%, hydrogen content≤0.00015wt%, non-metallic inclusion≤0.5 Level；Wire rod has good quenching degree, suitable intensity and hardness and excellent plasticity and toughness and cold-heading forge ability, no Need spheroidizing process can direct 10.9 grades of high-level standard components of cold upset forming process for producing, reduction manufacturing procedure and steel disappear Consumption, reduces production cost.

The present invention adds Al to play a part of crystal grain thinning and improve intensity in steel；Add micro B and a small amount of fixed nitrogen unit Plain Ti, is conducive to giving full play to the quenching degree of B, reaches the Proper Match of intensity, plasticity and toughness；Molten steel passes through VD vacuum refinings Handling process, significantly reduces gas content and field trash in steel, P≤0.012wt%, S≤0.005wt%, and oxygen content≤ 0.0015wt%, hydrogen content≤0.0002wt%, non-metallic inclusion≤0.5 grade is conducive to the improvement of steel plasticity and toughness；Roller Sequence controls relatively low start rolling temperature, enters final rolling temperature and laying temperature, promotes the refinement of ferrite crystal grain, the disk after having spun Strip adoption delaying type stelmor cooling mode carry out control it is cold, phase transformation is completed with slow cooling rate on stelmor roller-way, is obtained To fine grain ferrite+spheroidizing pearlite microscopic structure, the forge ability of steel is significantly improved.

The boracic high-intensity fasteners of present invention production are high with steel wire rod cleanliness factor, and field trash is few, with good through hardening Property, suitable intensity and hardness and excellent plasticity and toughness and cold-heading forge ability, it is not necessary to spheroidizing process can be straight 10.9 grades of high-level standard components of cold upset forming process for producing are connect, manufacturing procedure and steel consumption is reduced, is reduced production cost.

Specific embodiment

With reference to embodiment, the present invention is further illustrated, but never in any form the present invention is any limitation as, Based on present invention teach that any conversion for being made or replacement, belong to protection scope of the present invention.

The high intensity non-annealed steel for fastener wire rod of boracic of the present invention have the chemistry of following weight percents into Point：C 0.20~0.24wt%、Si≤0.04wt%、Mn 0.50~0.70wt%、Cr 0.25~0.35wt%、Ti 0.035~ 0.055wt% 、Als 0.035~0.055wt%、B 0.0045~0.0060wt%、S≤0.004wt%、P≤0.012wt%、O≤ 0.0015wt%, H≤0.00015wt%, remaining is Fe and inevitable impurity.

The preparation method of the high intensity non-annealed steel for fastener wire rod of boracic of the present invention, it is characterised in that include with Lower step：

A, molten iron pretreatment desulfurizing：By 4.5 ~ 5.0wt% of chemical composition C, 0.30 ~ 0.50wt% of Si, Mn 0.25 ~ 0.090 ~ 0.110wt% of 0.50wt%, P, S≤0.020wt%, remaining is the blast-melted fortune of Fe and inevitable impurity Desulfurization process are carried out to KR methods molten iron preprocessing unit, stirring-head insertion depth is controlled to 2200 ~ 2400mm, by 15.0 ~ 17.0 kg/t_SteelAmount, add routine CaO matter desulfurizing agent carry out desulfurization process, mixing time is controlled to 8 minutes；Stirring is carried out after terminating Take off rear slag operation, it is ensured that in ladle molten iron face it is exposed >=4/5, scratch clean desulfurization slag；After pretreatment, hot metal composition is controlled to：C 4.5~ 0.30 ~ 0.50wt% of 4.8wt%, Si, 0.25 ~ 0.50wt% of Mn, 0.090 ~ 0.110wt% of P, S≤0.004wt%, remaining is Fe And inevitable impurity；

B, smelting molten steel：By chemical composition C 4.5-4.8wt%, Si 0.30-0.50wt%, Mn 0.25-0.50wt%, P 0.090-0.110wt%, S≤0.004wt%, remaining be Fe and inevitable impurity step A pretreatment depth desulphurised hot metal, Chemical composition C 0.16-0.25wt%, Si 0.12-0.25 wt%, Mn 0.45-0.70wt%, P 0.015-0.030wt%, S 0.018-0.035wt%, remaining is the high-quality steel scrap and chemical composition C 3.2-3.4wt%, Si of Fe and inevitable impurity 0.30-0.50wt%, Mn 0.30-0.50 wt%, P 0.070-0.090wt%, S 0.020-0.035wt%, remaining is for Fe and not During the low-phosphorous sulphur pig iron of evitable impurity adds LD converter, carry out conventional top bottom blowing, respectively by 40.0 ~ 45.0kg/t_Steel、18.0~22.0kg/t_Steel、3.0~5.0kg/t_SteelAddition, add Calx, light dolomite, magnesite ball slag making, Control endpoint carbon content >=0.08wt%, tapping temperature≤1640 DEG C；Active lime is added to carry out slag to ladle bottom before tapping Wash, lime adding amount is 2.5kg/t_Steel；Using whole bottom argon blowing technology during tapping, argon flow amount is controlled to 20 ~ 35NL/min；

C, deoxidation alloying：Step B is smelted the molten steel tapping for finishing, when the molten steel amount in ladle is more than 1/4, is pressed Row deoxidation alloying order：Ferro-aluminum → high carbon ferro-chrome → high carbon ferromanganese, adds following material successively in ladle：By 2.2 ~ 3.0kg/t_SteelAmount, add following mass ratio ferro-aluminum：Al 70.5wt%, remaining is Fe and inevitable impurity；Press 4.1~5.8kg/t_SteelAmount, add following mass ratio high carbon ferro-chrome：Cr 56.7wt%, C 7.2wt%, remaining is Fe and can not The impurity for avoiding；By 5.4 ~ 8.1kg/t_SteelAmount, add following mass ratio high carbon ferromanganese：Mn 75.6wt%, C 6.7wt%, Remaining is Fe and inevitable impurity；Above-mentioned alloy is added when ladle molten steel amount reaches 4/5；After tapping is finished, by steel Water hangs delivers to LF stove refining procedures；

D, molten steel LF stove refines：Step C tapping is finished into molten steel it is hung to LF stove refine stations and connect argon gas band, opens argon Using the little argon amount Argon 2 minutes of 20 ~ 30NL/min, then bottom electrode adopts 7 ~ 9 grades of sluggings of gear；After being powered 3 minutes, lift electricity Slugging situation in pole observation stove, afterwards thermometric, sampling；If slag condition is diluter, 4.0 ~ 6.0kg/t of Calx is added_Steel, it is subsequently adding carbide 0.5kg/t_SteelResidue adjustment, controls basicity of slag for 5.5 ~ 7.0；According to steel sample analysis result, alloy, aluminum shot adjustment molten steel component are added, Control molten steel oxygen activity≤5ppm；It is 40 ~ 50NL/min suitably to increase argon flow amount afterwards, by 1.9 ~ 2.9kg/t_SteelAmount, plus Enter the ferrotianium of following mass ratio：Ti 33.5wt%, remaining is Fe and inevitable impurity, soft blow argon 3 minutes；Press afterwards 0.3~0.4kg/t_SteelAmount, add following mass ratio ferro-boron：B 21.5wt%, remaining is Fe and inevitable impurity, soft Argon 2 minutes；Afterwards liquid steel temperature is heated to wire feeding process is carried out after 1665 ~ 1675 DEG C, feeding has following mass ratio Aluminum calcium line：Ca 57.2wt%, Al 36.5wt%, remaining be Fe and inevitable impurity, wire-feeding velocity is 2.5m/s, line feeding Measure as 150m；Line feeding terminates to adopt flow to carry out molten steel for the little argon amount of 20 ~ 30NL/min soft blow argon, and the soft blow time is 2 Minute, add conventional big bag molten steel covering agent, addition to be controlled to 1.0kg/t afterwards_Steel, molten steel is hung to into VD stove vacuum fines then Refining station；

E, molten steel VD stove vacuum refinings：D step molten steel is hung to into VD vacuum refining furnace rear, Argon pipe is connected, argon is opened Using the little argon amount Argon 2 minutes of 20 ~ 30NL/min, oxygen is determined to molten steel afterwards and determines hydrogen, while thermometric sampling；After sampling is finished, Vacuum container cover car is opened to working position, close vacuum container cover, carry out evacuation, when vacuum is evacuated to 60Pa, proceed by fidelity empty Degassing process, while carrying out BOTTOM ARGON BLOWING process, argon flow amount is controlled to 40 ~ 60NL/min, the molten steel under the conditions of vacuum 60Pa 15 minutes degassing process time；Fruit storage closes vacuum main valve after finishing, lift cover, and liquid steel sampling is determined with oxygen is determined Hydrogen；Carry out little argon amount soft blow argon afterwards to process to molten steel, argon flow amount is 20 ~ 30NL/min, and soft argon blowing time is 2 minutes； After molten steel soft blow argon terminates, conventional big bag molten steel covering agent, addition is added to be controlled to 1.0kg/t_Steel, then molten steel is hung to and is poured Foundry work position；

F, molten steel casting：It it is 1525 ~ 1535 DEG C in tundish temperature, pulling rate is 2.1 ~ 2.3m/min, and Water Rate for Secondary Cooling Water is 1.1 ~ 1.3L/kg, M-EMS Current intensity be 300A, running frequency be 2.5Hz under conditions of, using the straight arcs of R9m The molten steel whole process protection of E steps is casting continuously to form the stream small billet casting machine of 5 machine of shape continuous straightening 5 steel billet of section 150mm × 150mm；

G, heating steel billet：F-step steel billet is sent in heating furnace of the soaking zone furnace temperature for 1080 ~ 1120 DEG C, heating 50 ~ 70 Minute, steel billet tapping temperature is 940 ~ 980 DEG C, goes out squama by water under high pressure, pushes to 5 base positions before inlet of rolling mill and treat that warm area is carried out The natural cooling of 3 ~ 5 minutes, finally enters mill milling with 900 ~ 920 DEG C of start rolling temperature；

H, controlled rolling and controlled cooling：The high-speed rod-rolling mill that the steel billet of G steps sends into 28 frames is rolled, in speed is Under the rolling condition of 0.15 ~ 0.25m/s, 6 passages of roughing；Afterwards under rolling condition of the speed for 10.0 ~ 15.0 m/s, in Roll 12 passages；Before carrying out finish rolling afterwards, pre- water-cooled control is cold, is 120 ~ 150m in cooling water inflow³Cold 2 ~ 3 seconds are controlled under/h；It Afterwards final rolling temperature be 840 ~ 860 DEG C, speed for 20 ~ 65m/s rolling condition under, 5 ~ 10 passages of finish rolling；Afterwards in temperature For 820 ~ 835 DEG C, speed is spinning under conditions of 20 ~ 65m/s；After spinning, wire rod carries out " delay " into Stanermo wind-cooling linear Type control cooling, i.e. Slow cooling；Blower fan Close All when Stanermo wind-cooling linear control is cold, opens Cover lid, roller table speed are controlled to 0.25 ~ 0.45m/s；After the air-cooled end of stelmor, collection volume temperature control is 550 ~ 600 DEG C, it Natural air cooling to room temperature will be coiled afterwards and obtains the high intensity non-annealed steel for fastener wire rod of boracic, with following weight percents Chemical composition：C 0.20~0.24wt%、Si≤0.04wt%、Mn 0.50~0.70wt%、Cr 0.25~0.35wt%、Ti 0.035~0.055wt% 、Als 0.035~0.055wt%、B 0.0045~0.0060wt%、S≤0.004wt%、P≤ 0.012wt%, O≤0.0015wt%, H≤0.00015wt%, remaining is Fe and inevitable impurity, the technologic mechanicses having Performance and microscopic structure and field trash are shown in Table 1, table 2：

1 boracic high-intensity fasteners of table steel coil rod technologic mechanicses performance

Table 2 boracic high-intensity fasteners steel coil rod microscopic structure and field trash

The specific implementation method of the present invention is as follows：

A, molten iron pretreatment desulfurizing：By blast-melted (chemical composition C 4.5-5.0wt%, Si 0.30-0.50wt%, Mn 0.25-0.50wt%, P 0.090-0.110wt%, S≤0.020wt%, remaining is Fe and inevitable impurity) it is transported to KR Method molten iron preprocessing unit carries out desulfurization process, and stirring-head insertion depth is controlled to 2200-2400mm, by 15.0 ~ 17.0kg/t_Steel Amount, add routine CaO matter desulfurizing agent carry out desulfurization process, mixing time is controlled to 8 minutes；Stirring carries out taking off rear slag after terminating Operation, it is ensured that in ladle molten iron face it is exposed >=4/5, scratch clean desulfurization slag；After pretreatment, hot metal composition is controlled to：C 4.5- 4.8wt%, Si 0.30-0.50wt%, Mn 0.25-0.50wt%, P 0.090-0.110wt%, S≤0.004wt%, remaining is Fe And inevitable impurity.

B, smelting molten steel：By pretreatment depth desulphurised hot metal (chemical composition C 4.5-4.8wt%, Si 0.30- of step A 0.50wt%, Mn 0.25-0.50wt%, P 0.090-0.110wt%, S≤0.004wt%, remaining is Fe and inevitably impure Thing), high-quality steel scrap (chemical composition C 0.16-0.25wt%, Si 0.12-0.25wt%, Mn 0.45-0.70wt%, P 0.015- 0.030wt%, S 0.018-0.035wt%, remaining is Fe and inevitable impurity) and low-phosphorous sulphur pig iron (chemical composition C 3.2-3.4wt%, Si 0.30-0.50wt%, Mn 0.30-0.50wt%, P 0.070-0.090wt%, S 0.020-0.035wt%, Remaining is Fe and inevitable impurity) add LD converter, carry out conventional top bottom blowing, respectively by 40.0 ~ 45.0kg/t_Steel、18.0~22.0kg/t_Steel、3.0~5.0kg/t_SteelAddition, add Calx, light dolomite, magnesite ball slag making, Control endpoint carbon content >=0.08wt%, tapping temperature≤1640 DEG C；Active lime is added to carry out slag to ladle bottom before tapping Wash, lime adding amount is 2.5kg/t_Steel；Using whole bottom argon blowing technology during tapping, argon flow amount is controlled to 20 ~ 35NL/min.

C, deoxidation alloying：Step B is smelted the molten steel tapping for finishing, when the molten steel amount in ladle is more than 1/4, is pressed Row deoxidation alloying order：Ferro-aluminum → high carbon ferro-chrome → high carbon ferromanganese, adds following material successively in ladle：By 2.2 ~ 3.0kg/t_SteelAmount, add following mass ratio ferro-aluminum：Al 70.5wt%, remaining is Fe and inevitable impurity；Press 4.1~5.8kg/t_SteelAmount, add following mass ratio high carbon ferro-chrome：Cr 56.7wt%, C 7.2wt%, remaining is Fe and can not The impurity for avoiding；By 5.4 ~ 8.1kg/t_SteelAmount, add following mass ratio high carbon ferromanganese：Mn 75.6wt%, C 6.7wt%, Remaining is Fe and inevitable impurity；Above-mentioned alloy is added when ladle molten steel amount reaches 4/5；After tapping is finished, by steel Water hangs delivers to LF stove refining procedures.

D, molten steel LF stove refines：Step C tapping is finished into molten steel it is hung to LF stove refine stations and connect argon gas band, opens argon Using little argon amount (20 ~ 30NL/min) Argon 2 minutes, then bottom electrode adopted 7 ~ 9 grades of sluggings of gear；After being powered 3 minutes, lift electricity Slugging situation in pole observation stove, afterwards thermometric, sampling；If slag condition is diluter, 4.0 ~ 6.0kg/t of Calx is added_Steel, it is subsequently adding carbide 0.5kg/t_SteelResidue adjustment, controls basicity of slag for 5.5 ~ 7.0；According to steel sample analysis result, alloy, aluminum shot adjustment molten steel component are added, Control molten steel oxygen activity≤5ppm；Argon flow amount (40 ~ 50NL/min) is increased afterwards suitably, by 1.9 ~ 2.9kg/t_SteelAmount, plus Enter the ferrotianium of following mass ratio：Ti 33.5wt%, remaining is Fe and inevitable impurity, soft blow argon 3 minutes；Press afterwards 0.3~0.4kg/t_SteelAmount, add following mass ratio ferro-boron：B 21.5wt%, remaining is Fe and inevitable impurity, soft Argon 2 minutes；Afterwards liquid steel temperature is heated to wire feeding process is carried out after 1665 ~ 1675 DEG C, feeding has following mass ratio Aluminum calcium line：Ca 57.2wt%, Al 36.5wt%, remaining be Fe and inevitable impurity, wire-feeding velocity is 2.5m/s, line feeding Measure as 150m；Line feeding terminates to adopt flow to carry out molten steel for the little argon amount of 20 ~ 30NL/min soft blow argon, and the soft blow time is 2 Minute, add conventional big bag molten steel covering agent, addition to be controlled to 1.0kg/t afterwards_Steel, molten steel is hung to into VD stove vacuum fines then Refining station.

E, molten steel VD stove vacuum refinings：D step molten steel is hung to into VD vacuum refining furnace rear, Argon pipe is connected, argon is opened Using little argon amount (20 ~ 30NL/min) Argon 2 minutes, oxygen is determined to molten steel afterwards and determines hydrogen, while thermometric sampling；After sampling is finished, Vacuum container cover car is opened to working position, close vacuum container cover, carry out evacuation, when vacuum is evacuated to 60Pa, proceed by fidelity empty Degassing process, while carrying out BOTTOM ARGON BLOWING process, argon flow amount is controlled to 40 ~ 60NL/min, the molten steel under the conditions of vacuum 60Pa 15 minutes degassing process time；Fruit storage closes vacuum main valve after finishing, lift cover, and liquid steel sampling is determined with oxygen is determined Hydrogen；Carry out little argon amount soft blow argon afterwards to process to molten steel, argon flow amount is 20 ~ 30NL/min, and soft argon blowing time is 2 minutes； After molten steel soft blow argon terminates, conventional big bag molten steel covering agent, addition is added to be controlled to 1.0kg/t_Steel, then molten steel is hung to and is poured Foundry work position.

F, molten steel casting：It it is 1525 ~ 1535 DEG C in tundish temperature, pulling rate is 2.1 ~ 2.3m/min, and Water Rate for Secondary Cooling Water is 1.1 ~ 1.3L/kg, M-EMS Current intensity be 300A, running frequency be 2.5Hz under conditions of, using the straight arcs of R9m The molten steel whole process protection of E steps is casting continuously to form the stream small billet casting machine of 5 machine of shape continuous straightening 5 steel billet of section 150mm × 150mm；

G, heating steel billet：F-step steel billet is sent in heating furnace of the soaking zone furnace temperature for 1080 ~ 1120 DEG C, heating 50 ~ 70 Minute, steel billet tapping temperature is 940 ~ 980 DEG C, goes out squama by water under high pressure, pushes to 5 base positions before inlet of rolling mill and treat that warm area is carried out The natural cooling of 3 ~ 5 minutes, finally enters mill milling with 900 ~ 920 DEG C of start rolling temperature；

H, controlled rolling and controlled cooling：The high-speed rod-rolling mill that the steel billet of G steps sends into 28 frames is rolled, in speed is Under the rolling condition of 0.15 ~ 0.25m/s, 6 passages of roughing；Afterwards under rolling condition of the speed for 10.0 ~ 15.0 m/s, in Roll 12 passages；Before carrying out finish rolling afterwards, pre- water-cooled control is cold, is 120 ~ 150m in cooling water inflow³Cold 2 ~ 3 seconds are controlled under/h；It Afterwards final rolling temperature be 840 ~ 860 DEG C, speed for 20 ~ 65m/s rolling condition under, 5 ~ 10 passages of finish rolling；Afterwards in temperature For 820 ~ 835 DEG C, speed is spinning under conditions of 20 ~ 65m/s；After spinning, wire rod carries out " delay " into Stanermo wind-cooling linear Type control cooling (i.e. Slow cooling)；Blower fan Close All when Stanermo wind-cooling linear control is cold, opens Cover lid, roller table speed are controlled to 0.25 ~ 0.45m/s；After the air-cooled end of stelmor, collection volume temperature control is 550 ~ 600 DEG C, it Natural air cooling to room temperature will be coiled afterwards obtains a kind of high intensity non-annealed steel for fastener coil rod of boracic, the temperature control of steel System, roller table speed regard different size and require concrete determination.

The high intensity non-annealed steel for fastener coil rod of a kind of boracic that the present invention is provided has following weight percents Chemical composition：C 0.20~0.24wt%、Si≤0.04wt%、Mn 0.50~0.70wt%、Cr 0.25~0.35wt%、Ti 0.035~ 0.055wt%、Als 0.035~0.055wt%、B 0.0045~0.0060wt%、S≤0.004wt%、P≤0.012wt%、O≤ 0.0015wt%, H≤0.00015wt%, remaining is Fe and inevitable impurity.

The present invention has following advantages and beneficial effect：

The preparation method of the high intensity non-annealed steel for fastener wire rod of boracic that the present invention is provided, adds Al to play carefully in steel Change crystal grain and improve the effect of intensity；Micro B and a small amount of nitrogen killer Ti is added, is conducive to giving full play to the quenching degree of B, is reached The Proper Match of intensity, plasticity and toughness；Molten steel makes gas content and field trash in steel aobvious by VD vacuum refining handling process Writing reduces, P≤0.012wt%, S≤0.005wt%, oxygen content≤0.0015wt%, hydrogen content≤0.00015wt%, nonmetallic folder Debris≤0.5 grade, is conducive to the improvement of steel plasticity and toughness；Steel rolling process controls relatively low start rolling temperature, enters final rolling temperature and tell Silk temperature, promotes the refinement of ferrite crystal grain, and the wire rod after having spun is controlled using delaying type stelmor cooling mode It is cold, phase transformation is completed with slow cooling rate on stelmor roller-way, fine grain ferrite+spheroidizing pearlite microscopic structure is obtained, The forge ability of steel is significantly improved.

The boracic high-intensity fasteners of present invention production are high with steel wire rod cleanliness factor, and field trash is few, with good through hardening Property, suitable intensity and hardness and excellent plasticity and toughness and cold-heading forge ability, it is not necessary to spheroidizing process can be straight 10.9 grades of high-level standard components of cold upset forming process for producing are connect, manufacturing procedure and steel consumption is reduced, is reduced production cost.

To be embodied as case, the present invention will be further described below：

Embodiment 1

A, molten iron pretreatment desulfurizing：By blast-melted (chemical composition C 4.5wt%, Si 0.30wt%, Mn 0.25wt%, P 0.090wt%, S 0.012wt%, remaining is Fe and inevitable impurity) it is transported to KR methods molten iron preprocessing unit and carries out desulfurization Process, stirring-head insertion depth is controlled to 2200-2400mm, by 15.0kg/t_SteelAmount, add routine CaO matter desulfurizing agent carry out Desulfurization process, mixing time are controlled to 8 minutes；Stirring terminate after carry out taking off rear slag operation, it is ensured that in ladle molten iron face it is exposed >= 4/5, scratch clean desulfurization slag；After pretreatment, hot metal composition is controlled to：C 4.5wt%、Si 0.30wt%、Mn 0.25wt% 、P 0.090wt%, S 0.002wt%, remaining is Fe and inevitable impurity.

B, smelting molten steel：By pretreatment depth desulphurised hot metal (chemical composition C 4.5wt%, Si 0.30wt%, Mn of step A 0.25wt%, P 0.090wt%, S 0.002wt%, remaining is Fe and inevitable impurity), high-quality steel scrap (chemical composition C 0.12 wt%, Mn 0.45wt%, P 0.015wt%, S 0.018wt% of 0.16wt%, Si, remaining is Fe and inevitably impure Thing) and low-phosphorous sulphur pig iron (chemical composition C 3.2wt%, Si 0.30wt%, Mn 0.30wt%, P 0.070wt%, S 0.020wt%, Remaining is Fe and inevitable impurity) LD converter is added, conventional top bottom blowing is carried out, respectively by 40.0kg/t_Steel、 18.0kg/t_Steel、3.0kg/t_SteelAddition, add Calx, light dolomite, magnesite ball slag making, control endpoint carbon content 0.08wt%, 1625 DEG C of tapping temperature；Active lime is added to carry out wash heat to ladle bottom before tapping, lime adding amount is 2.5kg/t_Steel；Using whole bottom argon blowing technology during tapping, argon flow amount is controlled to 20NL/min.

C, deoxidation alloying：Step B is smelted the molten steel tapping for finishing, when the molten steel amount in ladle is more than 1/4, is pressed Row deoxidation alloying order：Ferro-aluminum → high carbon ferro-chrome → high carbon ferromanganese, adds following material successively in ladle：By 2.2kg/t_Steel Amount, add following mass ratio ferro-aluminum：Al 70.5wt%, remaining is Fe and inevitable impurity；By 4.1kg/t_Steel's Amount, adds the high carbon ferro-chrome of following mass ratio：Cr 56.7wt%, C 7.2wt%, remaining is Fe and inevitable impurity；Press 5.4kg/t_SteelAmount, add following mass ratio high carbon ferromanganese：Mn 75.6wt%, C 6.7wt%, remaining is for Fe and unavoidably Impurity；Above-mentioned alloy is added when ladle molten steel amount reaches 4/5；After tapping is finished, molten steel is hung and delivers to LF stove refine works Sequence.

D, molten steel LF stove refines：Step C tapping is finished into molten steel it is hung to LF stove refine stations and connect argon gas band, opens argon Using little argon amount (20NL/min) Argon 2 minutes, then bottom electrode adopted 7 ~ 9 grades of sluggings of gear；After being powered 3 minutes, lift electrode Slugging situation in observation stove, afterwards thermometric, sampling；If slag condition is diluter, Calx 4.0kg/t is added_Steel, it is subsequently adding carbide 0.5kg/ t_SteelResidue adjustment, controls basicity of slag for 5.5；According to steel sample analysis result, alloy, aluminum shot adjustment molten steel component are added, molten steel oxygen is controlled Activity 5ppm；Argon flow amount (40NL/min) is increased afterwards suitably, by 1.9kg/t_SteelAmount, add following mass ratio ferrotianium： Ti 33.5wt%, remaining is Fe and inevitable impurity, soft blow argon 3 minutes；0.3kg/t is pressed afterwards_SteelAmount, add it is following The ferro-boron of mass ratio：B 21.5wt%, remaining is Fe and inevitable impurity, soft blow argon 2 minutes；Afterwards by liquid steel temperature Wire feeding process, aluminum calcium line of the feeding with following mass ratio are carried out after being heated to 1675 DEG C：Ca 57.2wt%、Al 36.5wt%、 Remaining is Fe and inevitable impurity, and wire-feeding velocity is 2.5m/s, and line feeding amount is 150m；Line feeding terminate to adopt flow for The little argon amount of 20NL/min carries out soft blow argon to molten steel, and the soft blow time is 2 minutes, adds conventional big Baogang water to cover afterwards Agent, addition are controlled to 1.0kg/t_Steel, molten steel is hung to into VD stove vacuum refining stations then.

E, molten steel VD stove vacuum refinings：D step molten steel is hung to into VD vacuum refining furnace rear, Argon pipe is connected, argon is opened Using little argon amount (20NL/min) Argon 2 minutes, oxygen is determined to molten steel afterwards and determines hydrogen, while thermometric sampling；After sampling is finished, will be true Slack tank lid car is opened to working position, and close vacuum container cover, carries out evacuation, when vacuum is evacuated to 60Pa, proceeds by guarantor's vacuum outgass Process, while carrying out BOTTOM ARGON BLOWING process, argon flow amount is controlled to 40 ~ 60NL/min, the liquid steel degassing under the conditions of vacuum 60Pa Process time 15 minutes；Fruit storage closes vacuum main valve after finishing, lift cover, to liquid steel sampling and determines oxygen and determines hydrogen； Carry out little argon amount soft blow argon afterwards to process to molten steel, argon flow amount is 20NL/min, soft argon blowing time is 2 minutes；Molten steel is soft After Argon terminates, conventional big bag molten steel covering agent, addition is added to be controlled to 1.0kg/t_Steel, molten steel is hung to into teemer then Position.

F, molten steel casting：It is 1535 DEG C in tundish temperature, pulling rate is 2.3m/min, and Water Rate for Secondary Cooling Water is 1.3L/kg, knot Brilliant device electromagnetic agitation current intensity be 300A, running frequency be 2.5Hz under conditions of, using straight 5 machines 5 of arc continuous straightening of R9m The molten steel whole process protection of E steps is casting continuously to form stream small billet casting machine the steel billet of section 150mm × 150mm.

G, heating steel billet：In being 1120 DEG C of heating furnace by F-step steel billet feeding soaking zone furnace temperature, heat 70 minutes, steel Base tapping temperature is 980 DEG C, goes out squama by water under high pressure, pushes to 5 base positions before inlet of rolling mill and treat that warm area carries out the nature of 3 minutes Cooling, finally enters mill milling with 920 DEG C of start rolling temperature.

H, controlled rolling and controlled cooling：The high-speed rod-rolling mill that the steel billet of G steps sends into 28 frames is rolled, in speed is Under the rolling condition of 0.25m/s, 6 passages of roughing；Afterwards speed for 15.0m/s rolling condition under, in roll 12 passages； Before carrying out finish rolling afterwards, pre- water-cooled control is cold, is 120m in cooling water inflow³Cold 2 seconds are controlled under/h；Afterwards final rolling temperature be 860 DEG C, speed is 10 passages of finish rolling under the rolling condition of 65m/s；Afterwards temperature be 835 DEG C, speed be 65m/s under conditions of Spinning；After spinning, wire rod carries out " delay " type control cooling (i.e. Slow cooling) into Stanermo wind-cooling linear；Stelmor wind Blower fan Close All when cold line control is cold, opens insulation shroud above front 3 Fans, and roller table speed is controlled to 0.25 ~ 0.45m/s； After the air-cooled end of stelmor, collection volume temperature control is 600 DEG C, will coil natural air cooling afterwards and obtains a kind of boracic to room temperature High intensity non-annealed steel for fastener coil rod, the chemical composition with following weight percents：C 0.20wt%、Si 0.04wt%、Mn 0.50wt%、Cr 0.25wt%、Ti 0.035wt%、Als 0.035wt%、B 0.0045wt%、 S 0.002wt%, P 0.007wt%, O 0.0015wt%, H 0.00015wt%, remaining is Fe and inevitable impurity.

The high intensity non-annealed steel for fastener coil rod technologic mechanicses performance of boracic that the present embodiment is prepared, micro- group Knit and field trash inspection is shown in Table shown in 3, table 4.

The boracic high-intensity fasteners steel coil rod technologic mechanicses performance of 3 the present embodiment of table production

Boracic high-intensity fasteners steel coil rod microscopic structure and the field trash of 4 the present embodiment of table production

Embodiment 2

A, molten iron pretreatment desulfurizing：By blast-melted (chemical composition C 4.8wt%, Si 0.40wt%, Mn 0.38wt%, P 0.102wt%, S 0.017wt%, remaining is Fe and inevitable impurity) it is transported to KR methods molten iron preprocessing unit and carries out desulfurization Process, stirring-head insertion depth is controlled to 2200-2400mm, by 16.0kg/t_SteelAmount, add routine CaO matter desulfurizing agent carry out Desulfurization process, mixing time are controlled to 8 minutes；Stirring terminate after carry out taking off rear slag operation, it is ensured that in ladle molten iron face it is exposed >= 4/5, scratch clean desulfurization slag；After pretreatment, hot metal composition is controlled to：C 4.6wt%、Si 0.40wt%、Mn 0.38wt%、P 0.102wt%, S 0.003wt%, remaining is Fe and inevitable impurity.

B, smelting molten steel：By pretreatment depth desulphurised hot metal (chemical composition C 4.6wt%, Si 0.40wt%, Mn of step A 0.38wt%, P 0.102wt%, S 0.003wt%, remaining is Fe and inevitable impurity), high-quality steel scrap (chemical composition C 0.20wt%, Si 0.18wt%, Mn 0.58wt%, P 0.021wt%, S 0.026wt%, remaining is Fe and inevitably impure Thing) and low-phosphorous sulphur pig iron (chemical composition C 3.3wt%, Si 0.40wt%, Mn 0.40wt%, P 0.080wt%, S 0.028wt%, Remaining is Fe and inevitable impurity) LD converter is added, conventional top bottom blowing is carried out, respectively by 42.0kg/t_Steel、 20.0kg/t_Steel、4.0kg/t_SteelAddition, add Calx, light dolomite, magnesite ball slag making, control endpoint carbon content 0.10wt%, 1635 DEG C of tapping temperature；Active lime is added to carry out wash heat to ladle bottom before tapping, lime adding amount is 2.5kg/t_Steel；Using whole bottom argon blowing technology during tapping, argon flow amount is controlled to 28NL/min.

C, deoxidation alloying：Step B is smelted the molten steel tapping for finishing, when the molten steel amount in ladle is more than 1/4, is pressed Row deoxidation alloying order：Ferro-aluminum → high carbon ferro-chrome → high carbon ferromanganese, adds following material successively in ladle：By 2.6kg/t_Steel Amount, add following mass ratio ferro-aluminum：Al 70.5wt%, remaining is Fe and inevitable impurity；By 5.4kg/t_Steel's Amount, adds the high carbon ferro-chrome of following mass ratio：Cr 56.7wt%, C 7.2wt%, remaining is Fe and inevitable impurity；Press 6.7kg/t_SteelAmount, add following mass ratio high carbon ferromanganese：Mn 75.6wt%, C 6.7wt%, remaining is for Fe and unavoidably Impurity；Above-mentioned alloy is added when ladle molten steel amount reaches 4/5；After tapping is finished, molten steel is hung and delivers to LF stove refine works Sequence.

D, molten steel LF stove refines：Step C tapping is finished into molten steel it is hung to LF stove refine stations and connect argon gas band, opens argon Using little argon amount (25NL/min) Argon 2 minutes, then bottom electrode adopted 7 ~ 9 grades of sluggings of gear；After being powered 3 minutes, lift electrode Slugging situation in observation stove, afterwards thermometric, sampling；If slag condition is diluter, Calx 5.0kg/t is added_Steel, it is subsequently adding carbide 0.5kg/ t_SteelResidue adjustment, controls basicity of slag for 6.2；According to steel sample analysis result, alloy, aluminum shot adjustment molten steel component are added, molten steel oxygen is controlled Activity 3ppm；Argon flow amount (46NL/min) is increased afterwards suitably, by 2.4kg/t_SteelAmount, add following mass ratio ferrotianium： Ti 33.5wt%, remaining is Fe and inevitable impurity, soft blow argon 3 minutes；0.36kg/t is pressed afterwards_SteelAmount, under addition The ferro-boron of row mass ratio：B 21.5wt%, remaining is Fe and inevitable impurity, soft blow argon 2 minutes；Afterwards by molten steel temperature Degree carries out wire feeding process, aluminum calcium line of the feeding with following mass ratio after being heated to 1670 DEG C：Ca 57.2wt%、Al 36.5wt%, remaining be Fe and inevitable impurity, wire-feeding velocity is 2.5m/s, and line feeding amount is 150m；Line feeding terminates to adopt Flow carries out soft blow argon for the little argon amount of 25NL/min to molten steel, and the soft blow time is 2 minutes, adds conventional big Baogang water afterwards Coverture, addition are controlled to 1.0kg/t_Steel, molten steel is hung to into VD stove vacuum refining stations then.

E, molten steel VD stove vacuum refinings：D step molten steel is hung to into VD vacuum refining furnace rear, Argon pipe is connected, argon is opened Using little argon amount (25NL/min) Argon 2 minutes, oxygen is determined to molten steel afterwards and determines hydrogen, while thermometric sampling；After sampling is finished, will be true Slack tank lid car is opened to working position, and close vacuum container cover, carries out evacuation, when vacuum is evacuated to 60Pa, proceeds by guarantor's vacuum outgass Process, while carrying out BOTTOM ARGON BLOWING process, argon flow amount is controlled to 50NL/min, under the conditions of vacuum 60Pa, liquid steel degassing is processed 15 minutes time；Fruit storage closes vacuum main valve after finishing, lift cover, to liquid steel sampling and determines oxygen and determines hydrogen；Afterwards Carry out little argon amount soft blow argon to process to molten steel, argon flow amount is 25NL/min, soft argon blowing time is 2 minutes；Molten steel soft blow argon After end, conventional big bag molten steel covering agent, addition is added to be controlled to 1.0kg/t_Steel, molten steel is hung to into casting station then.

F, molten steel casting：It is 1530 DEG C in tundish temperature, pulling rate is 2.2m/min, and Water Rate for Secondary Cooling Water is 1.2L/kg, knot Brilliant device electromagnetic agitation current intensity be 300A, running frequency be 2.5Hz under conditions of, using straight 5 machines 5 of arc continuous straightening of R9m The molten steel whole process protection of E steps is casting continuously to form stream small billet casting machine the steel billet of section 150mm × 150mm；

G, heating steel billet：In being 1100 DEG C of heating furnace by F-step steel billet feeding soaking zone furnace temperature, heat 60 minutes, steel Base tapping temperature is 960 DEG C, goes out squama by water under high pressure, pushes to 5 base positions before inlet of rolling mill and treat that warm area carries out the nature of 4 minutes Cooling, finally enters mill milling with 910 DEG C of start rolling temperature；

H, controlled rolling and controlled cooling：The high-speed rod-rolling mill that the steel billet of G steps sends into 28 frames is rolled, in speed is Under the rolling condition of 0.20m/s, 6 passages of roughing；Afterwards speed for 13.0m/s rolling condition under, in roll 12 passages； Before carrying out finish rolling afterwards, pre- water-cooled control is cold, is 135m in cooling water inflow³Cold 3 seconds are controlled under/h；Afterwards final rolling temperature be 850 DEG C, speed is 8 passages of finish rolling under the rolling condition of 48m/s；Afterwards temperature be 828 DEG C, speed be 48m/s under conditions of Spinning；After spinning, wire rod carries out " delay " type control cooling (i.e. Slow cooling) into Stanermo wind-cooling linear；Stelmor wind Blower fan Close All when cold line control is cold, opens insulation shroud above front 3 Fans, and roller table speed is controlled to 0.25 ~ 0.45m/s； After the air-cooled end of stelmor, collection volume temperature control is 580 DEG C, will coil natural air cooling afterwards and obtains a kind of boracic to room temperature High intensity non-annealed steel for fastener coil rod, the chemical composition with following weight percents：C 0.22wt%、Si 0.03wt%、Mn 0.60wt%、Cr 0.30wt%、Ti 0.046wt%、Als 0.045wt%、B 0.0052wt%、S 0.003wt%, P 0.010wt%, O0.0013wt%, H0.00012wt%, remaining is Fe and inevitable impurity.

The present embodiment provide a kind of high intensity non-annealed steel for fastener coil rod technologic mechanicses performance of boracic, micro- group Knit and field trash inspection is shown in Table shown in 5, table 6.

The boracic high-intensity fasteners steel coil rod technologic mechanicses performance of 5 the present embodiment of table production

Boracic high-intensity fasteners steel coil rod microscopic structure and the field trash of 6 the present embodiment of table production

Embodiment 3

A, molten iron pretreatment desulfurizing：By blast-melted (chemical composition C 5.0wt%, Si 0.50wt%, Mn 0.50wt%, P 0.110wt%, S 0.020wt%, remaining is Fe and inevitable impurity) it is transported to KR methods molten iron preprocessing unit and carries out desulfurization Process, stirring-head insertion depth is controlled to 2200-2400mm, by 17.0kg/t_SteelAmount, add routine CaO matter desulfurizing agent carry out Desulfurization process, mixing time are controlled to 8 minutes；Stirring terminate after carry out taking off rear slag operation, it is ensured that in ladle molten iron face it is exposed >= 4/5, scratch clean desulfurization slag；After pretreatment, hot metal composition is controlled to：C 4.8wt%、Si 0.50wt%、Mn 0.50wt%、P 0.110wt%, S 0.004wt%, remaining is Fe and inevitable impurity.

B, smelting molten steel：By pretreatment depth desulphurised hot metal (chemical composition C 4.8wt%, Si 0.50wt%, Mn of step A 0.50wt%, P 0.110wt%, S 0.004wt%, remaining is Fe and inevitable impurity), high-quality steel scrap (chemical composition C 0.25wt%, Si 0.25wt%, Mn 0.70wt%, P 0.030wt%, S 0.035wt%, remaining is Fe and inevitably impure Thing) and low-phosphorous sulphur pig iron (chemical composition C 3.4wt%, Si 0.50wt%, Mn 0.50wt%, P 0.090wt%, S 0.035wt%, Remaining is Fe and inevitable impurity) LD converter is added, conventional top bottom blowing is carried out, respectively by 45.0kg/t_Steel、 22.0kg/t_Steel、5.0kg/t_SteelAddition, add Calx, light dolomite, magnesite ball slag making, control endpoint carbon content 0.12wt%, 1640 DEG C of tapping temperature；Active lime is added to carry out wash heat to ladle bottom before tapping, lime adding amount is 2.5kg/t_Steel；Using whole bottom argon blowing technology during tapping, argon flow amount is controlled to 35NL/min.

C, deoxidation alloying：Step B is smelted the molten steel tapping for finishing, when the molten steel amount in ladle is more than 1/4, is pressed Row deoxidation alloying order：Ferro-aluminum → high carbon ferro-chrome → high carbon ferromanganese, adds following material successively in ladle：By 3.0kg/t_Steel Amount, add following mass ratio ferro-aluminum：Al 70.5wt%, remaining is Fe and inevitable impurity；By 5.8kg/t_Steel's Amount, adds the high carbon ferro-chrome of following mass ratio：Cr 56.7wt%, C 7.2wt%, remaining is Fe and inevitable impurity；Press 8.1kg/t_SteelAmount, add following mass ratio high carbon ferromanganese：Mn 75.6wt%, C 6.7wt%, remaining is for Fe and unavoidably Impurity；Above-mentioned alloy is added when ladle molten steel amount reaches 4/5；After tapping is finished, molten steel is hung and delivers to LF stove refine works Sequence.

D, molten steel LF stove refines：Step C tapping is finished into molten steel it is hung to LF stove refine stations and connect argon gas band, opens argon Using little argon amount (30NL/min) Argon 2 minutes, then bottom electrode adopted 7 ~ 9 grades of sluggings of gear；After being powered 3 minutes, lift electrode Slugging situation in observation stove, afterwards thermometric, sampling；If slag condition is diluter, Calx 6.0kg/t is added_Steel, it is subsequently adding carbide 0.5 kg/t_SteelResidue adjustment, controls basicity of slag for 7.0；According to steel sample analysis result, alloy, aluminum shot adjustment molten steel component are added, molten steel is controlled Oxygen activity 2ppm；Argon flow amount (50NL/min) is increased afterwards suitably, by 2.9kg/t_SteelAmount, add following mass ratio titanium Ferrum：Ti 33.5wt%, remaining is Fe and inevitable impurity, soft blow argon 3 minutes；0.4kg/t is pressed afterwards_SteelAmount, add The ferro-boron of following mass ratio：B 21.5wt%, remaining is Fe and inevitable impurity, soft blow argon 2 minutes；Afterwards by molten steel Temperature carries out wire feeding process, aluminum calcium line of the feeding with following mass ratio after being heated to 1665 DEG C： Ca 57.2wt%、Al 36.5wt%, remaining be Fe and inevitable impurity, wire-feeding velocity is 2.5m/s, and line feeding amount is 150m；Line feeding terminates to adopt Flow carries out soft blow argon for the little argon amount of 30NL/min to molten steel, and the soft blow time is 2 minutes, adds conventional big Baogang water afterwards Coverture, addition are controlled to 1.0 kg/t_Steel, molten steel is hung to into VD stove vacuum refining stations then.

E, molten steel VD stove vacuum refinings：D step molten steel is hung to into VD vacuum refining furnace rear, Argon pipe is connected, argon is opened Using little argon amount (30NL/min) Argon 2 minutes, oxygen is determined to molten steel afterwards and determines hydrogen, while thermometric sampling；After sampling is finished, will be true Slack tank lid car is opened to working position, and close vacuum container cover, carries out evacuation, when vacuum is evacuated to 60Pa, proceeds by guarantor's vacuum outgass Process, while carrying out BOTTOM ARGON BLOWING process, argon flow amount is controlled to 60NL/min, under the conditions of vacuum 60Pa, liquid steel degassing is processed 15 minutes time；Fruit storage closes vacuum main valve after finishing, lift cover, to liquid steel sampling and determines oxygen and determines hydrogen；Afterwards Carry out little argon amount soft blow argon to process to molten steel, argon flow amount is 30NL/min, soft argon blowing time is 2 minutes；Molten steel soft blow argon After end, conventional big bag molten steel covering agent, addition is added to be controlled to 1.0kg/t_Steel, molten steel is hung to into casting station then.

F, molten steel casting：It is 1525 DEG C in tundish temperature, pulling rate is 2.1m/min, and Water Rate for Secondary Cooling Water is 1.1L/kg, knot Brilliant device electromagnetic agitation current intensity be 300A, running frequency be 2.5Hz under conditions of, using straight 5 machines 5 of arc continuous straightening of R9m The molten steel whole process protection of E steps is casting continuously to form stream small billet casting machine the steel billet of section 150mm × 150mm.

G, heating steel billet：In being 1080 DEG C of heating furnace by F-step steel billet feeding soaking zone furnace temperature, heat 50 minutes, steel Base tapping temperature is 940 DEG C, goes out squama by water under high pressure, pushes to 5 base positions before inlet of rolling mill and treat that warm area carries out the nature of 5 minutes Cooling, finally enters mill milling with 900 DEG C of start rolling temperature.

H, controlled rolling and controlled cooling：The high-speed rod-rolling mill that the steel billet of G steps sends into 28 frames is rolled, in speed is Under the rolling condition of 0.15m/s, 6 passages of roughing；Afterwards speed for 10.0m/s rolling condition under, in roll 12 passages； Before carrying out finish rolling afterwards, pre- water-cooled control is cold, is 150m in cooling water inflow³Cold 3 seconds are controlled under/h；Afterwards final rolling temperature be 840 DEG C, speed is 5 passages of finish rolling under the rolling condition of 20m/s；Afterwards temperature be 820 DEG C, speed be 20m/s under conditions of Spinning；After spinning, wire rod carries out " delay " type control cooling (i.e. Slow cooling) into Stanermo wind-cooling linear；Stelmor wind Blower fan Close All when cold line control is cold, opens insulation shroud above front 3 Fans, and roller table speed is controlled to 0.25 ~ 0.45m/s； After the air-cooled end of stelmor, collection volume temperature control is 550 DEG C, will coil natural air cooling afterwards and obtains a kind of boracic to room temperature High intensity non-annealed steel for fastener coil rod, the chemical composition with following weight percents：C 0.24 wt%、Si 0.02wt%、Mn 0.70wt%、Cr 0.35wt%、Ti 0.055wt%、Als 0.055wt%、B 0.0060wt%、 S 0.004wt%, P 0.012wt%, O 0.0012wt%, H≤0.0001wt%, remaining is Fe and inevitable impurity.

The present embodiment provide a kind of high intensity non-annealed steel for fastener coil rod technologic mechanicses performance of boracic, micro- group Knit and field trash inspection is shown in Table shown in 7, table 8.

The boracic high-intensity fasteners steel coil rod technologic mechanicses performance of 7 the present embodiment of table production

Boracic high-intensity fasteners steel coil rod microscopic structure and the field trash of 8 the present embodiment of table production

Claims (1)

1. the preparation method of the high intensity non-annealed steel for fastener wire rod of a kind of boracic, the high intensity non-annealed securing member of the boracic There is the chemical composition of following weight percents with steel wire rod：C 0.20~0.24wt%、Si≤0.04wt%、Mn 0.50~ 0.70wt%、Cr 0.25~0.35wt%、Ti 0.035~0.055wt%、Als 0.035~0.055wt%、B 0.0045~ 0.0060wt%, S≤0.004wt%, P≤0.012wt%, O≤0.0015wt%, H≤0.00015wt%, remaining is Fe and can not keep away The impurity exempted from；It is characterized in that the preparation method of the high intensity non-annealed steel for fastener wire rod of the boracic includes following step Suddenly：

A, molten iron pretreatment desulfurizing：By 4.5 ~ 5.0wt% of chemical composition C, 0.30 ~ 0.50wt% of Si, 0.25 ~ 0.50wt% of Mn, P 0.090 ~ 0.110wt%, S≤0.020wt%, remaining is that to be transported to KR method molten iron pre- for Fe and inevitable impurity blast-melted Processing meanss carry out desulfurization process, and stirring-head insertion depth is controlled to 2200 ~ 2400mm, by 15.0 ~ 17.0 kg/t_SteelAmount, plus Entering conventional CaO matter desulfurizing agent carries out desulfurization process, and mixing time is controlled to 8 minutes；Stirring carries out taking off rear slag operation after terminating, and protects Card ladle in molten iron face it is exposed >=4/5, scratch clean desulfurization slag；After pretreatment, hot metal composition is controlled to：C 4.5~4.8wt%、Si 0.30 ~ 0.50wt%, 0.25 ~ 0.50wt% of Mn, 0.090 ~ 0.110wt% of P, S≤0.004wt%, remaining is for Fe and unavoidably Impurity；

B, smelting molten steel：By chemical composition C 4.5-4.8wt%, Si 0.30-0.50wt%, Mn 0.25-0.50wt%, P 0.090-0.110wt%, S≤0.004wt%, remaining be Fe and inevitable impurity step A pretreatment depth desulphurised hot metal, Chemical composition C 0.16-0.25wt%, Si 0.12-0.25wt%, Mn 0.45-0.70wt%, P 0.015-0.030wt%, S 0.018-0.035wt%, remaining is the high-quality steel scrap and chemical composition C 3.2-3.4wt%, Si of Fe and inevitable impurity 0.30-0.50wt%, Mn 0.30-0.50wt%, P 0.070-0.090wt%, S 0.020-0.035wt%, remaining is Fe and can not During the low-phosphorous sulphur pig iron of the impurity for avoiding adds LD converter, conventional top bottom blowing is carried out, respectively by 40.0 ~ 45.0kg/ t_Steel、18.0~22.0kg/t_Steel、3.0~5.0kg/t_SteelAddition, add Calx, light dolomite, magnesite ball slag making, control is eventually Point carbon content >=0.08wt%, tapping temperature≤1640 DEG C；Active lime is added to carry out wash heat, Calx to ladle bottom before tapping Addition is 2.5kg/t_Steel；Using whole bottom argon blowing technology during tapping, argon flow amount is controlled to 20 ~ 35NL/min；

C, deoxidation alloying：Step B is smelted the molten steel tapping for finishing, when the molten steel amount in ladle is more than 1/4, by following de- Oxygen alloyization order：Ferro-aluminum → high carbon ferro-chrome → high carbon ferromanganese, adds following material successively in ladle：By 2.2 ~ 3.0kg/t_Steel Amount, add following mass ratio ferro-aluminum：Al 70.5wt%, remaining is Fe and inevitable impurity；By 4.1 ~ 5.8kg/ t_SteelAmount, add following mass ratio high carbon ferro-chrome：Cr 56.7wt%, C 7.2wt%, remaining is Fe and inevitably impure Thing；By 5.4 ~ 8.1kg/t_SteelAmount, add following mass ratio high carbon ferromanganese：Mn 75.6wt%, C 6.7wt%, remaining be Fe and Inevitable impurity；Above-mentioned alloy is added when ladle molten steel amount reaches 4/5；After tapping is finished, molten steel is hung and delivers to LF Stove refining procedure；

D, molten steel LF stove refines：Step C tapping is finished into molten steel it is hung to LF stove refine stations and connect argon gas band, opens argon and adopt The little argon amount Argon of 20 ~ 30NL/min 2 minutes, then bottom electrode is using 7 ~ 9 grades of sluggings of gear；After being powered 3 minutes, lift electrode is seen Slugging situation in stove is examined, afterwards thermometric, sampling；If slag condition is diluter, 4.0 ~ 6.0kg/t of Calx is added_Steel, it is subsequently adding carbide 0.5kg/t_SteelResidue adjustment, controls basicity of slag for 5.5 ~ 7.0；According to steel sample analysis result, alloy, aluminum shot adjustment molten steel component are added, Control molten steel oxygen activity≤5ppm；It is 40 ~ 50NL/min suitably to increase argon flow amount afterwards, by 1.9 ~ 2.9kg/t_SteelAmount, plus Enter the ferrotianium of following mass ratio：Ti 33.5wt%, remaining is Fe and inevitable impurity, soft blow argon 3 minutes；Press afterwards 0.3~0.4kg/t_SteelAmount, add following mass ratio ferro-boron：B 21.5wt%, remaining is Fe and inevitable impurity, soft Argon 2 minutes；Afterwards liquid steel temperature is heated to wire feeding process is carried out after 1665 ~ 1675 DEG C, feeding has following mass ratio Aluminum calcium line：Ca 57.2wt%, Al 36.5wt%, remaining be Fe and inevitable impurity, wire-feeding velocity is 2.5m/s, line feeding Measure as 150m；Line feeding terminates to adopt flow to carry out molten steel for the little argon amount of 20 ~ 30NL/min soft blow argon, and the soft blow time is 2 Minute, add conventional big bag molten steel covering agent, addition to be controlled to 1.0kg/t afterwards_Steel, molten steel is hung to into VD stove vacuum fines then Refining station；

E, molten steel VD stove vacuum refinings：D step molten steel is hung to into VD vacuum refining furnace rear, Argon pipe is connected, argon is opened and is adopted The little argon amount Argon of 20 ~ 30NL/min 2 minutes, determines oxygen to molten steel afterwards and determines hydrogen, while thermometric sampling；After sampling is finished, will be true Slack tank lid car is opened to working position, and close vacuum container cover, carries out evacuation, when vacuum is evacuated to 60Pa, proceeds by guarantor's vacuum outgass Process, while carrying out BOTTOM ARGON BLOWING process, argon flow amount is controlled to 40 ~ 60NL/min, the liquid steel degassing under the conditions of vacuum 60Pa Process time 15 minutes；Fruit storage closes vacuum main valve after finishing, lift cover, to liquid steel sampling and determines oxygen and determines hydrogen； Carry out little argon amount soft blow argon afterwards to process to molten steel, argon flow amount is 20 ~ 30NL/min, and soft argon blowing time is 2 minutes；Molten steel After soft blow argon terminates, conventional big bag molten steel covering agent, addition is added to be controlled to 1.0kg/t_Steel, molten steel is hung to into teemer then Position；

F, molten steel casting：Tundish temperature be 1525 ~ 1535 DEG C, pulling rate be 2.1 ~ 2.3m/min, Water Rate for Secondary Cooling Water be 1.1 ~ 1.3L/kg, M-EMS Current intensity are 300A, running frequency, under conditions of 2.5Hz, to be connected using the straight arcs of R9m The molten steel whole process protection of E steps is casting continuously to form continuous aligning 5 machine 5 stream small billet casting machine the steel billet of section 150mm × 150mm；

G, heating steel billet：F-step steel billet is sent in heating furnace of the soaking zone furnace temperature for 1080 ~ 1120 DEG C, 50 ~ 70 points are heated Clock, steel billet tapping temperature are 940 ~ 980 DEG C, by high-pressure water descaling, push to 5 base positions before inlet of rolling mill treat warm area carry out 3 ~ The natural cooling of 5 minutes, finally enters mill milling with 900 ~ 920 DEG C of start rolling temperature；

H, controlled rolling and controlled cooling：The high-speed rod-rolling mill that the steel billet of G steps sends into 28 frames is rolled, speed be 0.15 ~ Under the rolling condition of 0.25m/s, 6 passages of roughing；Afterwards speed for 10.0 ~ 15.0m/s rolling condition under, in roll 12 Passage；Before carrying out finish rolling afterwards, pre- water-cooled control is cold, is 120 ~ 150m in cooling water inflow³Cold 2 ~ 3 seconds are controlled under/h；Afterwards in essence Temperature is rolled for 840 ~ 860 DEG C, speed is 5 ~ 10 passages of finish rolling under the rolling condition of 20 ~ 65m/s；Afterwards temperature be 820 ~ 835 DEG C, speed is spinning under conditions of 20 ~ 65m/s；After spinning, wire rod carries out the control of " delay " type into Stanermo wind-cooling linear Cooling, i.e. Slow cooling；Blower fan Close All when Stanermo wind-cooling linear control is cold, opens insulation shroud above front 3 Fans, roller Road speed controlling is 0.25 ~ 0.45m/s；After the air-cooled end of stelmor, collection volume temperature control is 550 ~ 600 DEG C, will be coiled afterwards Natural air cooling to room temperature obtains the high intensity non-annealed steel for fastener wire rod of boracic, the chemistry with following weight percents into Point：C 0.20~0.24wt%、Si≤0.04wt%、Mn 0.50~0.70wt%、Cr 0.25~0.35wt%、Ti 0.035~ 0.055wt%、Als 0.035~0.055wt%、B 0.0045~0.0060wt%、S≤0.004wt%、P≤0.012wt%、O≤ 0.0015wt%, H≤0.00015wt%, remaining is Fe and inevitable impurity, the technologic mechanicses performance having and micro- group Knit and field trash is shown in Table 1, table 2：

1 boracic high-intensity fasteners of table steel coil rod technologic mechanicses performance

Table 2 boracic high-intensity fasteners steel coil rod microscopic structure and field trash

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