CN111154955A - Production method of ultra-deep drawing cold rolling enamel steel - Google Patents

Abstract

The invention relates to a production method of ultra-deep drawing cold-rolled enamel steel, belonging to the technical field of cold-rolled plate strip production. The invention adopts Ti-IF steel component system, and adopts hot rolling high-temperature finish rolling and high-temperature curling to obtain a structure which is ferrite after annealing at a larger cold rolling reduction rate, and the invention has the advantages ofExcellent mechanical property and anti-scaling property, wherein the yield strength is about 150MPa, the tensile strength is about 300MPa, the elongation (A80) is about 43 percent, the r90 value is about 2.7, the n90 value is about 0.23, and the European standard anti-scaling sensitivity TH value is 15min/mm²About, after 30 days of aging, the enamel has no scale explosion. The product produced by the invention has excellent surface quality, excellent ultra-deep drawing performance and scale explosion resistance, and good economic benefit.

Description

Production method of ultra-deep drawing cold rolling enamel steel

Technical Field

The invention relates to a production method of ultra-deep drawing cold-rolled enamel steel, belonging to the technical field of cold-rolled plate strip production.

Background

"ultra-deep drawing steel" is a term of art for steel, which has excellent formability and excellent property uniformity, and is interstitial-free steel having a very low carbon content and added with alloy stabilizing elements. It is a steel which does not suffer from aging.

The enamel product is a composite material prepared by coating and fusing inorganic oxide coating (porcelain enamel) on the surface of an enamel steel substrate by adopting a melting and sintering method, has the characteristics of wear resistance, corrosion resistance, high temperature resistance, easiness in washing, no toxicity, sanitation and the like, and is widely used for manufacturing household utensils, sanitary wares, water heater liners, chemical reaction tanks, building decorative panels and the like. The most easily-produced quality problems of the enamel steel are stamping cracking and enamel scaling, the scaling is mainly caused by the fact that no enough hydrogen storage trap exists in the steel, and in the ultra-deep-drawing enamel steel, the quantity of second-phase particles is a key factor for determining the scaling resistance and the forming performance of a steel plate. If the contents of carbon, nitrogen and sulfur in the steel are low, the steel quality is pure, and the formability of the steel sheet is good, but the fishscale resistance of the steel sheet is poor because there are not enough second phase particles in the steel. On the other hand, if the content of the impurity element in the steel is high, the formability of the steel sheet is poor and the requirement of the extra-deep drawability cannot be met. The improvement of the fish scaling resistance and the stamping performance are restricted by contradictions, and the key is to solve the pair of contradictions, realize good comprehensive performance matching and realize reasonable component design and process control. Representative patents currently in use for the production of deep drawing enamelled steel include the following:

CN102251192A discloses a production method of enamel steel for cold rolling water heater, which comprises the following components of less than or equal to 0.050 percent of C, less than or equal to 0.10 percent of Si, less than or equal to 0.50 percent of Mn, less than or equal to 0.035 percent of P, less than or equal to 0.035 percent of S, 0.031-0.10 percent of Al, less than or equal to 0.015 percent of N, more than or equal to 0.001 percent of O, 0.0003-0.020 percent of B, 0.01-0.50 percent of Cu, 0.01-0.10 percent of Nb0.01-0.10 percent of V, 0.01-0.15 percent of Ti, and one or; also contains one or more than two of 0.01 to 0.10 percent of Cr0.01 to 0.10 percent of Ni0.01 to 0.10 percent of Mo0.01 to 0.10 percent, wherein the total amount is controlled to be 0.01 to 0.30 percent; the balance of iron and inevitable impurities. The process is characterized in that the hot rolling finishing temperature is 700-950 ℃, and the coiling temperature is 550-750 ℃; the cold rolling reduction rate is more than 60%, the continuous annealing or cover annealing is carried out, the annealing temperature is 650-900 ℃, the heat preservation time is 1 minute-20 hours, and the enamel steel has good formability, anti-scaling property, adherence and anti-pinhole defect, and is suitable for manufacturing household appliance parts, sanitary wares, kitchen utensils and building decoration panels. The scheme adopts a B, Nb and Ti composite adding low-carbon steel system, the alloy cost is high, and the ultra-deep drawing performance is general.

CN100396808C discloses cold-rolled enamel steel with scale explosion resistance and ultra-deep drawing property, which is prepared from the following components in percentage by weight: c: less than or equal to 0.0050%, Mn: 0.10 to 0.30%, Si: less than or equal to 0.030 percent, P: less than or equal to 0.015%, S: 0.010-0.050%, Als: 0.020-0.050%, N: 0.004 to 0.015% of Ti, (4C +3.42N +1.5S) + (0.02 to 0.04%), and the balance of Fe and other inevitable impurities. The manufacturing method sequentially comprises the following steps: smelting, vacuum degassing treatment, continuous casting, hot rolling, acid washing, cold rolling, annealing and finishing, wherein the heating temperature of hot continuous rolling is 1100-1250 ℃, the finishing rolling temperature is 860-920 ℃, the coiling temperature is 680-760 ℃, the cold rolling reduction rate of cold continuous rolling is more than 65%, a cover type annealing mode is adopted, an annealing furnace is in a full hydrogen atmosphere, nitrogen is controlled to be not more than 10%, and the annealing temperature is 680-750 ℃. The proposal adopts a hood-type annealing process, and the fish scaling resistance is general.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: provides a production method of ultra-deep drawing cold rolling enamel steel, which has excellent mechanical property and scaling resistance and better economy.

In order to solve the technical problems, the invention adopts the technical scheme that: the production method of the ultra-deep drawing cold rolling enamel steel comprises the following steps: casting the molten steel into a blank, hot rolling, acid rolling and continuous annealing to obtain enamel steel;

the molten steel comprises the following chemical components in percentage by weight: 0.003-0.008% of C, less than or equal to 0.03% of Si, 0.10-0.20% of Mn, 0.070-0.110% of Ti, less than or equal to 0.015% of P, 0.015-0.030% of S, 0.010-0.050% of Als0.002-0.008% of N, and the balance of Fe and inevitable impurities;

in the hot rolling procedure, heating to 1200-1240 ℃ for rough rolling, wherein the final rolling temperature is 910-950 ℃, and cooling to 720-780 ℃ in the front section for coiling to obtain a hot rolled coil;

in the acid rolling process, the hot rolled coil is subjected to acid washing and cold rolling to form cold-rolled thin strip steel, wherein the cold rolling reduction rate is 70-85%;

in the continuous annealing process, the temperature of the soaking section is 820-840 ℃, and the heat preservation time is 60-180 s; the slow cooling end point temperature is 650-700 ℃; the final temperature of the fast cooling stage is 420-440 ℃, and the cooling rate of the fast cooling stage is controlled to be more than 25 ℃/s; the temperature of the overaging section is 300-430 ℃; the flat elongation is set to 0.4% -0.6%.

Further, the method comprises the following steps: in the acid rolling process, the cold rolling reduction is 80-85%.

The invention provides a method for producing ultra-deep drawing cold rolling enamel steel, which adopts a Ti-IF steel component system, and adopts hot rolling high-temperature final rolling and high-temperature curling to obtain a structure which is ferrite after annealing with a larger cold rolling reduction rate, and has excellent mechanical property and anti-scaling property, wherein the yield strength is about 150MPa, the tensile strength is about 300MPa, the elongation (A80) is about 43 percent, the r90 value is about 2.7, the n90 value is about 0.23, and the European standard anti-scaling sensitivity TH value is 15min/mm²About, after 30 days of aging, the enamel has no scale explosion.

The invention forms a key technology for producing the ultra-deep drawing cold rolling enamel steel on a continuous annealing unit. The invention adopts the Ti-IF steel component system with low cost to produce, and can obtain the enamel steel with good scale-explosion resistance and mechanical property even IF expensive alloy elements are not added. The product produced by the invention has excellent surface quality, excellent ultra-deep drawing performance and scale explosion resistance, and good economic benefit.

Drawings

FIG. 1 is a microstructure diagram of an enamel steel obtained in example 1;

FIG. 2 is a microstructure diagram of an enamel steel obtained in example 2.

Detailed Description

The raw materials and equipment used in the embodiment of the present invention are known products and obtained by purchasing commercially available products.

The invention provides a production method of ultra-deep drawing cold rolling enamel steel, which comprises the following steps: casting the molten steel into a blank, hot rolling, acid rolling and continuous annealing to obtain enamel steel; the detailed process route is as follows: molten iron pretreatment → smelting → vacuum degassing treatment → continuous casting → hot rolling → acid rolling → continuous annealing → leveling → surface quality inspection → oiling → coiling → finished product, the enamel steel plate with yield strength of 110 MPa-200 MPa, good surface quality, excellent forming performance and excellent fish scaling resistance is obtained.

The molten steel comprises the following chemical components in percentage by weight: 0.003-0.008% of C, less than or equal to 0.03% of Si, 0.10-0.20% of Mn, 0.070-0.110% of Ti, less than or equal to 0.015% of P, 0.015-0.030% of S, 0.010-0.050% of Als0.002-0.008% of N, and the balance of Fe and inevitable impurities.

The reason for selecting the above chemical components and ranges thereof in the present invention is as follows: carbon: the important elements affecting the performance of the steel plate, the carbon content is reduced, the elongation of the steel plate is improved, and the n value and the r value are also improved. Nitrogen and sulfur: the traditional ultra-low carbon steel belongs to impurity elements, which affect the formability of a steel plate, but in the enamel steel, the proper increase of the contents of sulfur and nitrogen is beneficial to matching with other alloy elements in the steel, forming second phase particles and improving the hydrogen storage performance. Titanium: titanium is a strong carbon, nitrogen and sulfide forming element, and an excess of titanium is added to fix interstitial atoms of carbon, nitrogen and sulfur in steel.

The specific technological parameters are controlled as follows:

in the hot rolling procedure, heating to 1200-1240 ℃ for rough rolling, wherein the final rolling temperature is 910-950 ℃, and cooling to 720-780 ℃ in the front section for coiling to obtain a hot rolled coil; the size and distribution of the second phase particles in the matrix are controlled by high-temperature coiling. In the hot rolling step, a more preferable control parameter is 930 ℃.

In the acid rolling process, the hot rolled coil is subjected to acid washing and cold rolling to form cold-rolled thin strip steel, wherein the cold rolling reduction rate is 70-85%; the large reduction rate is beneficial to improving the r value of the annealed strip steel and the stamping performance of the steel plate, and simultaneously the reduction rate is improved, so that the number of gaps formed around a precipitated phase is increased, and the fish scaling resistance is improved; in the acid rolling step, the cold rolling reduction may be more preferably 80% to 85%.

In addition, in consideration of equipment requirements and economy of a continuous annealing unit, in a continuous annealing process, the temperature of a soaking section is 820-840 ℃, the heat preservation time is 60-180 s, the slow cooling end point temperature is 650-700 ℃, the end point temperature of a fast cooling section is 420-440 ℃, the cooling rate of the fast cooling section is controlled to be more than 25 ℃/s, the temperature of an overaging section is 300-430 ℃, the leveling elongation is set to be 0.4-0.6%, a chilled substrate enters a continuous annealing furnace after being welded and cleaned, grains after annealing are prevented from being coarsened by adopting fast heating in recovery and recrystallization temperature areas of a steel plate, the content of solid-solution carbon in steel and gamma → α transformation are controlled in the slow cooling stage through the slow cooling rate, the {111} texture is fully developed, the steel strip is ensured to have a higher r value, different parameter values are selected according to the thickness range of the steel strip, and the yield point extension of the steel strip is eliminated.

In conclusion, the Ti-IF steel component system is adopted, hot rolling and high-temperature finish rolling and high-temperature curling are carried out, the structure is ferrite after annealing, and the Ti-IF steel has excellent mechanical property and anti-fishscaling property, wherein the yield strength is about 150MPa, the tensile strength is about 300MPa, the elongation (A80) is about 43 percent, the r90 value is about 2.7, the n90 value is about 0.23, and the European standard anti-fishscaling sensitivity TH value is 15min/mm²About, after 30 days of aging, the enamel has no scale explosion. The product produced by the invention has excellent surface quality, excellent ultra-deep drawing performance and scale explosion resistance, and good economic benefit.

Example the method of the invention is adopted to produce the ultra-deep drawing cold rolling enameled pressed steel

Example 1: selectingThe chemical compositions of example 1 in Table 1 were measured, the thickness of the enameled steel sheet was 0.6mm, the hot rolling temperature was controlled as shown in Table 2, the cold rolling reduction was 82.9%, the annealing temperature was 826 ℃, and the continuous annealing process was controlled as shown in Table 3. The flat elongation is 0.5%, the transverse mechanical properties of the finished product are shown in Table 4, and the microstructure is shown in FIG. 1. The enamel coating trial production is carried out, the coating has good adherence and has no scale explosion phenomenon after 30 days of aging. The hydrogen permeation test is carried out by adopting European standard EN10209-2013, and the TH value is 15.22min/mm²。

Example 2: the chemical compositions of example 2 in table 1 were selected for production, the thickness of the enamel steel sheet was 0.8mm, the hot rolling temperature was controlled as shown in table 2, the cold rolling reduction was 81.2%, the annealing temperature was 836 ℃, and the control of the continuous annealing process was shown in table 3. The flat elongation was 0.5%, and the transverse mechanical properties of the final product are shown in Table 4, and the microstructure is shown in FIG. 2. The enamel coating trial production is carried out, the coating has good adherence and has no scale explosion phenomenon after 30 days of aging. The hydrogen permeation test is carried out by adopting European standard EN10209-2013, and the TH value is 16.57min/mm²。

TABLE 1 chemical composition/% of examples

Numbering	C	Si	Mn	P	S	Als	Ti	Fe and other unavoidable impurities
									Example 1	0.0032	0.006	0.12	0.006	0.024	0.025	0.076	99.7398
Example 2	0.0061	0.006	0.16	0.007	0.017	0.027	0.091	99.6859

TABLE 2 Hot Rolling Process of examples

Table 3 continuous annealing process of the example

TABLE 4 mechanical properties of the examples

Numbering	Yield strength (MPa)	Tensile strength (MPa)	Elongation A80(％)	n90 value	r90 value
						Example 1	132	308	44.5	0.24	2.75
Example 2	145	309	44.0	0.23	2.75

Claims (2)

1. The production method of the ultra-deep drawing cold rolling enamel steel comprises the following steps: the method comprises the following steps of casting molten steel into a blank, hot rolling, acid rolling and continuous annealing to obtain the enamel steel, and is characterized in that:

the molten steel comprises the following chemical components in percentage by weight: 0.003-0.008% of C, less than or equal to 0.03% of Si, 0.10-0.20% of Mn, 0.070-0.110% of Ti, less than or equal to 0.015% of P, 0.015-0.030% of S, 0.010-0.050% of Als, 0.002-0.008% of N and the balance of Fe and inevitable impurities;

in the hot rolling procedure, heating to 1200-1240 ℃ for rough rolling, wherein the final rolling temperature is 910-950 ℃, and cooling to 720-780 ℃ in the front section for coiling to obtain a hot rolled coil;

in the acid rolling process, the hot rolled coil is subjected to acid washing and cold rolling to form cold-rolled thin strip steel, wherein the cold rolling reduction rate is 70-85%;

in the continuous annealing process, the temperature of the soaking section is 820-840 ℃, and the heat preservation time is 60-180 s; the slow cooling end point temperature is 650-700 ℃; the final temperature of the fast cooling stage is 420-440 ℃, and the cooling rate of the fast cooling stage is controlled to be more than 25 ℃/s; the temperature of the overaging section is 300-430 ℃; the flat elongation is set to 0.4% -0.6%.

2. The method for producing extra-deep drawing cold-rolled enamel steel as claimed in claim 1, wherein: in the acid rolling process, the cold rolling reduction is 80-85%.

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