JPS6036755A - Composite cylinder liner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to the provision of tough composite cylinder liners.

Cylinder liners used in internal combustion engines must have wear resistance and seizure resistance because they must slide together with piston rings and maintain airtightness. For this purpose, special cast iron castings containing A-type graphite and wear-resistance-improving elements such as Or, B, P, V, Mo, and Nb have been used exclusively for cylinder liners. .

However, with the recent increase in the size of internal combustion engines and the desire to make them lighter and more fuel efficient, the quality of conventional engines has become insufficient in terms of strength. Improvement is desperately needed.

For the purpose of improving strength, it is possible to select a liner material with high strength, but this would impair the wear resistance and fire resistance, which are the essential characteristics of cylinder liners. There is, in fact, a "two-limit ascending."

It is also effective to increase the thickness of the buiner, but in this case it goes against the objective of making the bj lighter.

By the way, when analyzing the usage conditions and causes of damage to cylinder twiners, we find that: (1) The only part that requires wear resistance and 11iI (r) resistance is the part that contacts the piston ring, that is, the inner surface of the liner.

(it) Breakage of the cylinder twiner starts from its outer surface.

I know that.

The present invention aims to achieve the following objectives by applying an unprecedented finishing technology to the cylinder liner in view of this point.

That is, the composite cylinder liner of the present invention has an inner layer (near the inner surface) made of a special cast iron material with a specific chemical composition that is excellent in Fi wear resistance and seizure resistance, while an outer layer (near the outer surface) is made of a special cast iron material with excellent toughness. Specific 5. It is made of spheroidal graphite cast iron material 7, and the two are welded and joined to achieve the intended purpose without impairing the use characteristics of the overall required wear resistance and surface sintering f4゛ property. This was a successful study of the improvement in strength.

The present invention will be explained in detail below.

The composite cylinder liner of the present invention has a structure as shown in FIG. That is, the outer layer a is made of a spheroidal graphite cast iron material with excellent toughness, which will be described in detail later, while the inner layer is made of a special cast iron material with a specific chemical composition that has excellent baking resistance and wear resistance, and both are welded together. It is composed of an integrated structure.

By welding and integrating the outer layer a and the inner layer, a welded layer (intermediate layer) having a composition intermediate between the outer layer a and the inner layer inevitably occurs. That is,
By welding the inner layer to the outer layer a, some degree of welding of the outer layer material into the inner layer is inevitable.

The multilayer composite cylinder liner of the present invention can be easily manufactured by centrifugal casting. Sunoh-6 That is, after casting the outer layer, the inner layer is cast at an appropriate timing to integrate the two.

Note that any of horizontal type, inclined type, and vertical type can be applied to the centrifugal force casting method.

Next, a description will be given of the spheroidal graphite tdJ iron material forming the outer layer of the composite cylinder liner of the present invention.

The present invention is characterized by using a material having the following component composition as the outer layer material of the liner which is susceptible to toughness. That is, the outer layer has a weight M% of 02.6~4.0°811.5
~8.5%, MnO, 2~1.0%, PO,8
% or less, SO, 04 or less, MgO, 02~o,
196 and; lJt 2.51 u below, (]rO, 8%
Hereinafter, MO0.6% or less, sno, a% or less, octaearth element 0.1% or less, Ou4.0% or less, Aj, Oa,
Ba.

1 type or 2 or more types of Sr with a total valence of 0.2 or less
It is a spheroidal graphite cast iron material containing one or more species, the balance being Fe and normal impurities, and mainly consisting of spheroidal graphite and pearlite base.

Therefore, the chemical composition, microscopic structure, etc. of the above-mentioned specific material will be described in item -1.

(1) Chemical composition A7 0: 2.6-4.0 The spheroidal graphite cast iron material of the outer layer consists of spheroidal graphite and a matrix (
However, small amounts of cementite crystallization are not a problem), and toughness is particularly important. However, if it is less than 02.64, castability deteriorates and the amount of cementite crystallized increases, making the material brittle, while if it exceeds 4.0%, casting defects are likely to occur.

Si: 1.5 to 8.5 coefficient Sl has the effect of promoting graphitization, and in the case of this material in which Mg is added as a graphite nodularizing agent, if the coefficient is less than 1.5, the amount of cementite crystallization increases. , because it becomes brittle. However, if it exceeds 8.5%, the base becomes ferrite and the proof strength deteriorates, and the sl dissolved into the ferrite makes the ferrite brittle.

Mn: 0.2 to 1.0% Mn usually combines with S to eliminate the adverse effects of SL:D, and also stabilizes the base pearlite and increases its strength. MnO
, less than 2%, this effect cannot be expected, and on the other hand, if it exceeds 1.0%, it becomes brittle.

P: 0.8% or less Pit improves the fluidity of the molten metal, but it also produces phosphorus in the material, making the material brittle. This effect increases as the P content increases, but a value of 0.8 is considered to be within a range that does not cause any real harm.
Limited to two. Although the presence of P is advantageous in terms of low root toughness, in practice it is difficult to reduce the Po to less than 01 due to cost considerations.

S: greater than or equal to 0.04 Similar to P, S is generally understood as an impurity element and deteriorates mechanical properties.゛Also, since it has the effect of inhibiting the spheroidization of graphite, it should be kept at a coefficient of 0.04 or less.

Mg: 0.02% to O1 Mg is of course added to make graphite spheroidal, but if it is less than 0.02%, the effect is insufficient;
This is because if it exceeds 1%, it is undesirable because it tends to cause chilling effect of lJg and casting defects such as dross.

Horse 9 Ni, Or, Mo, Ni Ni, Or, Mo, an are effective in improving toughness, nt 2.5% or less, Or 0.8% or less, M
o 0.6% or less, SnO, type 1 or 2 below B
By containing more than 100% of the content, the liner can be made tougher.

The effect of each and the reason for limiting the ingredients will be explained below.

Ni: 2.5% or lessN1 acts effectively on graphitization and strengthening the base, but 2.5% or less
If it exceeds %, it is not only disadvantageous in terms of economic efficiency, but also
This is because quenched structures (bainite, martensite) and untransformed shrinkage tend to occur, which does not meet the purpose of the outer layer material. Incidentally, it is effective to preferably contain the amount of 0.5 or more.

Or: coefficient of 0.8 or less Or acts to strengthen the base and stabilize cementite. That is, when Oro exceeds 8%, 0, S
Adjustment of l also causes cementite to crystallize and become brittle.
The material of the outer layer meets the purpose of 10 and disappears.
．． Inclusion of one or more parts is effective.

MO: MO of 0.6 or less is effective for strengthening the base, but even if the content of sardines is increased too much, the effect will become saturated and it will not be economical.
Since it also has the effect of making it brittle, the coefficient is set to 0.6 or less. still,
Preferably, it is effective to contain 01-F or more.

sn: 0.8v or less Depending on the construction conditions of the outer layer 41, there may be too much ferrite in the base, resulting in a decrease in yield strength and fatigue strength. In that case, it is effective to add N, which has a pearlite stabilizing effect, within a range of 0.8% by weight at which the effect is saturated. In addition, preferably (1,0
A content of 8% or more is effective.

Rare earth element 20.1≠If a rare earth element is added in combination with Mg, the spheroidization of graphite will be better. At this time, the effect of the additive is saturated. 1mM [is the upper limit of All]. Preferably, the content of O2% or more is effective.

Ou: 4.0 coefficient or less Similar to Ou and Sn, it has the effect of suppressing the precipitation of ferrite and stabilizing pearlite. - Still improves corrosion resistance. The outer surface of the cylinder liner is generally water-cooled, and corrosion from the outer surface can also cause damage to the liner (corrosion fatigue).

Therefore, if O is added, the accident resistance will be further improved, but the effect will be saturated even if it exceeds 4.0%.
The upper limit is %. Incidentally, it is effective to contain preferably a coefficient of 0.1 or more.

AI! , Oa, Ba, Or: It is known that inoculation is performed in which the sum of one or more types is 0.2 or less for the purpose of microstructuring and graphitization. As will be described later, the material quality of the liner of the present invention can be improved by inoculation.

The inoculation effect fades over time, so
For items that require a long time to solidify, such as thick-walled castings, ordinary FeSi cannot be expected to have much of an inoculating effect. In that case, if one or more of these elements are contained, the sustainability of the inoculation will be improved. For this purpose, 1
The total damage of seeds or 2 &IJd-1: should be less than 0.2 chiles, and if more than that is contained, the quality of Shi51 young spores will not be proportionally improved, which will be disadvantageous in terms of cost. In addition, preferably 0.
A content of 0.02% or more is effective.

(li) Inoculation of outer layer material In general, inoculation is effective for refining the casting structure and promoting graphitization. If the inoculation technique is applied to the above-mentioned materials as well, it is possible to obtain particles in which graphite is distributed finely and uniformly. At this time, the inoculation port has a Si content of 0.05 to 1
．． 0% is appropriate.

That is, if it is less than 0.05%, no inoculation effect can be expected, and on the other hand, if it exceeds 140%, a corresponding effect cannot be obtained. Generally, r゛θS1 is suitable as an inoculant, but
) As a substance that enhances the inoculation effect, OaSi-i, O
By using FeSi insulator containing 11 layers or two or more of a, A/, Ba, and r, a fine and uniform material of 1B silk weave can be obtained. Note that the WM of the 81-containing fan at the inoculation edge is adjusted to the above-mentioned limited component range.

(1) The microscopic casting structure of the outer layer material of the gh spheroidal graphite cast iron material is mainly composed of spheroidal graphite and pearlite F base. Although a small amount of cementite may be crystallized in the tissue, since cementite is brittle, it is necessary to keep it as low as possible for the purpose of the present invention.

For the base, pearlite is preferable from the viewpoint of strength and fatigue strength.
It is better to use as little ferrite as possible. Incidentally, even if bainite or martensite partially precipitates, it may become somewhat brittle, but may actually have the advantage of increased strength. However, in order to precipitate bainite and martensite, it is necessary to take measures such as high alloying or special heat treatment, which is disadvantageous in terms of cost.

Next, the special cast iron material forming the inner layer of the composite cylinder liner of the present invention will be explained.

The present invention provides a liner with excellent wear resistance and seizure resistance.
4. An inner layer material (~) is characterized by using a material having the following component composition. That is, the inner layer has a weight.

02.5-4.0%, Eli 0.8-2.5
%, MnO, 8-1.5%.

P O, 05 to 1.5%, S O 68 or less,
Ni2. jltφ or less, Orl, 5% or less, no 0
．． 84 or less, 8n O, 5% or less + Oa 4.0 or less, B, T1. , V, Wb, Zr, total of 1.0% or less, A/, Oa, B
a, Sr.

A combination of one or more rare earth elements i10.2≠
It is a cast iron material containing one or more of the following; the remainder being Fθ and normal impurities.

Therefore, the chemical composition, microscopic structure, etc. of the above-mentioned specific material will be explained in detail below.

(1) Chemical composition 0: 2.5-4.0 The inner layer material needs to have seizure resistance and wear resistance. )is necessary. If it is less than 2.5%, both the graphite content and the carbide content will be insufficient, and the burning resistance and abrasion resistance will deteriorate. On the other hand, if it exceeds 4.0 cm, the amount of graphite and carbide will increase too much and it will become brittle.

Si: Coefficient 0.8 to 2.5 Sl has a graphitized layer and is an important element that determines the ratio between the amount of graphite and the amount of carbide. If it is less than 0.8 q6, the amount of graphite will be insufficient and the seizure resistance will deteriorate. When the ratio exceeds 2.5, the amount of carbides decreases and wear resistance deteriorates.

Mn: 0.8-1.5% Mn is effective in removing the harmful effects of β and strengthening bases.

For this purpose, a coefficient of 0.8 or more is required. On the other hand 1.
If it exceeds 5 yen, it becomes too hard and brittle.

P: coefficient of 0.05 to 1.5 P is generally known as an element that deteriorates the mechanical properties of materials, but in the liner inner layer material, by containing P, a P eutectic is generated, P eutectic is an effective element in that it has a great effect on improving seizure resistance and wear resistance. In order to improve seizure resistance and wear resistance,
．． If it is less than 0.6%, the effect cannot be expected, and
O-36755 (5) If the ratio exceeds 1.5, the mechanical properties deteriorate, chips fall off, and wear becomes more likely to occur.

S: 0.8 coefficient U or less S is a so-called impurity element that deteriorates the tlUM properties of the material, but it is set to be 0.8 coefficient or less as a range that does not cause problems as an inner layer material of the present invention. Note that the day is most effective in excluding the influence of Mg in the outer layer. However, even in that case, it is not necessary to exceed the 0.8 ratio.

Ni, Or, Mo, 5n Ni, C! r, Mo, and Sn are effective for strengthening the base and increasing toughness and hardness, Ni: 2.5% or less + a r: 1-' i or less, MO: 0.8- or less, Sn: 0. By containing 5% or less of one or more types, the wear resistance of the liner of the present invention can be further improved. The effects of each of these elements and reasons for limiting the components will be described below.

Ni: 2.5% or lowerN1 effectively strengthens the base, but if it exceeds 2.5%, it is not only disadvantageous in terms of economic efficiency, but also hardened structures (bainite, martensite),
Untransformed tissue is more likely to occur and becomes more brittle. In addition, seizure is likely to occur. Note that a content of 0.5% or more is effective.

Or a 1.5chi or less Like N1, it is effective for strengthening the base, but on the other hand, it has a strong tendency to produce determined monsters. Therefore, when the ratio exceeds 1.5, the amount of graphite decreases, and the seizure resistance and toughness deteriorate. Incidentally, it is effective to contain preferably a coefficient of 0.1 or more.

Mo: greater than 0.8 Like N1, it is effective in strengthening the base, but if it exceeds 0.8, it becomes a problem in terms of economics and hardening structure formation. Incidentally, it is effective to contain preferably a coefficient of 0.1 or more.

an: 0.5 coefficient or less An has the effect of suppressing ferrite and stabilizing pearlite. However, in the case of this material, the effect is saturated even when the angle exceeds 0.5 inch, so it is set to 1, angle 18 0.5 coefficient or less. Note that it is effective to preferably contain 0.08% or more.

Ou: 4.0% or less Like Bn, Ou has the effect of suppressing ferrite and stabilizing pearlite, but it also has a large effect of improving corrosion resistance. Since the edge wear on the inner surface of the liner includes corrosive wear, in order to improve the wear resistance, it is better to include O to obtain better agglomeration.

In that case, the upper limit should be the 4.0 coefficient at which the corrosion resistance improving effect is saturated. Incidentally, it is effective to contain preferably a coefficient of 0.1 or more.

B, Ti, V, Nt+, Zr: One or more types Total of 1.0- or less In order to improve wear resistance, the purpose is to generate P eutectic and cementite (iron carbide). However, in order to further improve surface J abrasion resistance, it is effective to generate highly hard carbides. B, Ti, V, Nb, and Zr are suitable for this purpose, and all of them produce carbides with higher hardness than cementate.
19. However, since these are all strong deoxidizers, if they are contained in large amounts, they reduce the fluidity of the molten metal and tend to cause casting defects.

Therefore, it should be kept at 1.0% or less. In addition, preferably 0.
A content of 0.02% or more is effective.

It is known that inoculation of A/, Oa, Ba, Sr, and 81 or more rare earth elements is carried out for the purpose of microstructural refinement and graphitization of 0.2 molar ratio or less. As will be described later, the liner of the present invention can also be inoculated to improve the properties of many materials.

The inoculation effect fades over time, so
For items that require a long time to solidify, such as thick-walled castings, ordinary Fe51 cannot be expected to be very effective in inoculating. In that case, the sustainability of inoculation is improved by containing one or more of these elements. For this purpose, 1
The total content of the species or two or more species may be 0.12% or less, and if the content is more than that, the effect will not increase proportionally, which is disadvantageous in terms of cost. Incidentally, the content is preferably 0.02% or more to be effective.

(1) Inoculation of inner layer material In general, inoculation is effective for refining sequelae and promoting graphitization. If the inoculation technique is applied to the above-mentioned material, a material in which graphite is more finely and uniformly distributed can be obtained. At this time, the inoculation amount ° is 0.06 ~ 1 min.
1.0chi is appropriate.

That is, if it is less than 0.05%, no inoculation effect can be expected, and on the other hand, if it exceeds 1.0%, a corresponding effect cannot be obtained. Ii'eSi is generally suitable as an inoculant, but Cadi and O
There is FeS2 containing one or more of a, A/, Ba, Or, and rare earth elements, and by using this, a material with a finer and more uniform structure can be obtained. Note that the s1-containing soil after inoculation is adjusted to the above-mentioned limited component range.

(1) Inner layer material: microscopic bell silk fabric It consists of monoclinic graphite, carbide, P eutectic, and base.

The base is preferably pearlite, and ferrite reduces wear resistance, so it is better to use as little as possible. Furthermore, if bainite or martensite precipitates in the base, it will have high hardness and improve wear resistance, but it will be more likely to cause seizure, so it is desirable to minimize it as much as possible.

As described above, the present invention consists of an outer layer material and an inner layer material having a specific chemical composition, and is further subjected to heat treatment as described below.

That is, the centrifugally cast composite cylinder liner is annealed at a temperature below the austenite range for the purpose of stabilizing the structure and eliminating strain.

Usually the temperature for this purpose is 400-660°C.

Compared to this strain relief annealing, it is disadvantageous in terms of cost, but it improves the toughness of the material, increases the hardness of the base structure, and
In terms of uniformity of the matrix structure, it is possible to improve the material quality by performing heat treatment at a temperature in the austenite region. The temperature range varies depending on whether the objective is toughness or high hardness, but generally 800 to 1000°C is appropriate. If the temperature is maintained in this temperature range, especially if the purpose is to increase the hardness, it is necessary to increase the cooling rate (even for a large cylinder liner with an inner diameter of 740 mm, the cooling rate is 20 mm in some parts).

'Possible up to C/Hr position). The edges thus heat treated at a temperature in the austenite region are usually additionally subjected to strain relief annealing at 400 to 65 G'C.

Next, examples of the present invention are listed and explained <Examples> Table 1 A) + A2) under the following casting conditions.
Manufactured 8 composite cylinder liners.

O Casting mold inner diameter: 6400 0 Casting method: Horizontal centrifugal casting OGA: a4oOteGA 120 aOfIA
Inclusive thickness: Outer layer 80 Mjl Inner layer 50 ffjl O chemical composition: Shown in Table 1 (heavy M, balance Fe and impurities) O hardness distribution (HB): Shown in M2 diagram O mechanical properties: Shown in Table 2 The general mechanical properties of the conventional single-layer cylinder liner are in the range of tensile strength of 18~25A28 kg/d and elongation of 0.2~0.8 modulus.

Regarding the microscopic structures of cylinder liners with diameters of 5,600 (outer layer material) and 4,600 (inner layer material) of cylinder liners 41 to A8, Ya 1 is shown in FIG. II (outer layer) and Figure 4 1. II (inner layer), A2 in Figure 5 1. II (outer layer) and Figure 6 1. II (inner layer), A8 as shown in Figure 7 ■.

(2) (outer layer) and Fig. 8 I, n (inner layer). However,■
The magnification is 50, and the magnification is 40G.

0 product: This cast product is cut to have an outer diameter of 600 Q and an inner diameter of 4.
A 40y cylinder liner was obtained.

Flat 26 Table 2 Mechanical Properties (Tensile Test) Inner layer: 046G Outer layer: Melo 60 As mentioned above, the composite cylinder liner of the present invention is suitable for use as a starting point for fracture, especially for liners that are required to have excellent toughness. The outer layer is made of spheroidal graphite iron material with the specific chemical composition mentioned above, while the inner layer of the liner is made of special cast iron material with a specific chemical composition that has excellent seizure resistance and abrasion resistance that matches the usage characteristics. In addition, since the two are welded together, it is possible to achieve high strength without impairing the inherent usability characteristics of the inner surface of the liner.

Furthermore, by utilizing the centrifugal force casting method, the machine cylinder liner according to the present invention can be easily manufactured with desired characteristics, and there is no problem with the welding between the layers.

[Brief Description of the Drawings] Fig. 1 is a cross-sectional view showing the structure of the composite cylinder liner according to the present invention, and Fig. 2 is a hardness distribution graph of the example. The hardness is shown on the axis. Figure 8 ■, ■ to Figure 8 1. FIG. 8I is a micrograph of an example of the machine cylinder liner of the present invention. II, ed. 5 Figure 1. II and Figure 7 1. II shows the outer layer tissue, Fig. 4 I, II, Fig. 6 1. II and Figure 8 1. II
indicates the inner layer tissue, respectively. (a)...outer layer, (b)...inner layer Applicant Kubota Iron Works Co., Ltd. Figure 5 (1) No. 61・Zl (1) :1iS5 Figure a No. 1s li (X) No. 7 Figure (Month No. 81) 1 (11 Figure 7 (1) No. 8 Written Amendment to Procedures (Forms) February 8, 1971, 1981 Kasa Patent No. 145496 2 Issued Akira's name double association cylinder liner 3, person making the amendment, relationship with cattle Patent applicant/applicant (105) Kuda Chichiko Meishiki Company 4 agent Kumo 577 422-

Claims (1)

[Scope of Claims] 1. At the neck hook: 0: 2.6 to 4.0 81: 1.5 to 8.5φ Mn: 0.2 to 1.0% P: 0. A: 0.04% or less Mg: 0.02-0.1%, Ni: 2.5% or less Or: 0.8% or less Mo: 0.6% or less Eln: 0.8% or less Rare earth elements: 0.1% or less Gu: 4.0% or less A4. Total of one or more of Oa, Ba, and Dayr = 0
．． C: 2.5-4.0φ Si: 0.8-2,5≠ Mn: 0.8-1.5% P: 0.05-1.5% S: O, a≠ or less, IJi: 2. 5 ≠ or less Or: t59b or less Mo: 0.8 or less an: 0.5 or less Ou: 4.0 or less B, Ti, V, Wb, Zr, one or more types total 8
1.0% or less AJ, Oa, Ba, SR, rare earth elements, or an alloy of two or more types: Contains one or more of the following: 0.2% or less - L, the balance is Fe and normal impurities A composite cylinder liner characterized by being formed by welding and joining an inner layer consisting of and.