JPS5846542B2 - Steel piston ring material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to piston ring materials, and more particularly to a combination piston ring material for internal combustion engines.

In recent years, internal combustion engines have been required to have increasingly higher performance, higher output, and higher speeds.In addition, they must also have measures against exhaust gases, and there is a need for countermeasures to the problems of reduced horsepower and increased fuel consumption of internal combustion engines. is increasing.

Regarding these problems, piston rings that maintain the airtightness of the combustion chamber of an internal combustion engine have a great influence on the performance of the internal combustion engine, and countermeasures are especially needed.

Conventionally, cast carbon steel rings or silicone chrome steel oil tempered wire have been used for oil rings in internal combustion engines, but casting rings are difficult to manufacture because they are thin in the axial direction. Since the high-temperature strength is low, the material has a relatively large cross-sectional area and is heavy, resulting in a large inertia and a problem in that it is likely to cause a fluttering phenomenon.

In addition, cast rings and silicon chrome rings lack wear resistance and heat resistance, and the rings cannot be installed near the top of the piston, which is advantageous for exhaust gas countermeasures, and the spacing between the rings is small. Because this is not possible, the weight of the piston becomes heavy, making it impossible to achieve high output and high speed.

The present invention was made in view of these problems, and has higher strength, wear resistance, and heat resistance than conventional ring materials, and provides good airtightness without causing the fluff phenomenon. The present invention relates to an oil ring material that can achieve high output and high speed of an internal combustion engine while maintaining the same.

That is, the present invention has an alloy composition of 0.5 to 0.8% C, Cr
10.0-15.5%, Si20.0%, M, n≦2
．． 0%, Mo0.2-1.5% and W
O, 3-3.0%, VO, 1-1.0% Nb0.01-
A martensitic stainless steel containing 0.3% and used in a heat-treated state, containing about 5 to 15% of undissolved carbides,
It also has excellent resistance to tempering and softening, has extremely high strength at high temperatures, and has excellent airtightness with the cylinder.

It also has good wear resistance and heat resistance. Furthermore, as a feature of the present invention, in conventional materials, a surface treatment layer such as Cr plating is formed on the sliding surface in order to lower the coefficient of friction with the cylinder wall, but with the present invention, there is no need for a surface treatment layer, and the temperature is sufficiently high. By adding MoW, V and Nb to conventional martensitic stainless steel, it is possible to improve performance and simplify the process at the same time.

The reasons for limiting the composition of the present invention will be described below.

C imparts high strength and wear resistance, and for that purpose it is necessary to contain at least 0.5%.

However, if the C content is high, bending workability deteriorates and ring straightening becomes difficult, so the upper limit was set at 0.8%.

Cr combines with C to form carbide, which improves wear resistance and seizure resistance as well as heat resistance. However, if too much Cr is present, heat treatment hardness decreases and formability deteriorates. ~15.5% was set as the claimed range.

Si is usually contained as a deoxidizing agent, but it also has the effect of improving heat resistance and cleanliness.

However, if it is contained in a large amount, the processability will deteriorate, so 2.
The scope of the patent claims.

Mn is also normally contained as a deoxidizing agent, but it has the effect of improving bending workability.

However, if the content is too large, the hardness decreases, so the claimed range is 2% or less.

Mo is one of the most important component elements of the material of the present invention and increases strength, heat resistance, cracking resistance, and abrasion resistance at high temperatures.

It also increases corrosion resistance when coexisting with Cr, and is particularly effective as an oil ring for diesel internal combustion engines, where corrosion resistance is a problem.

In order for Mo to exhibit these effects, it is necessary to have a content of 0.2% or more, but even if it is contained in a content of 1.5% or more, the effect will not increase much and the cost will increase, so the content should be 0.2 to 1.5%. % was defined as the claimed range.

W has the effect of increasing wear resistance and heat resistance,
For this purpose, 0.3% or more is required, but since there is no effect commensurate with the content even if the content is 3% or more, the claimed range is set at 3%.

Like W, V also increases abrasion resistance and heat resistance.

For the above effect, V is required to be 0.1% or more,
If it exceeds 1%, the effect will not increase much and workability will deteriorate, so the claimed range is 0.1 to 1.0%.

Nb has the effect of increasing wear resistance and heat resistance, and at the same time making crystal grains finer and improving bending workability.

For this purpose, o, oi% is effective, but if it exceeds 0.3%, the workability will deteriorate significantly, so 0.01 to 0.3
% was defined as the claimed range.

. Next, the effects of the present invention will be explained using examples.

Table 1 shows the chemical compositions of the steel materials of the present invention, conventional steel materials, and comparative steel materials.

The inventive steel material and the N comparative material shown in A- in Table 2 are obtained by casting the inventive steel material and the comparative steel material using a normal electric steel manufacturing method, hot plastic working the coils, and then cold plastic working. The product was repeatedly annealed to obtain the desired dimensions, formed into a ring at high temperatures, and then subjected to quenching heat treatment to restrict its shape to form a piston ring product.

Conventional materials L are cast, M are coiled, cold worked, oil tempered, heat treated and straightened.

However, Table 2 shows a comparison of the properties of the ring products after heat treatment.

However, when heat resistance is f5m/m, each heat treatment is applied to obtain the hardness of each symbol, and the load required to bend a 151-length round bar to a radius of curvature of 25mmR at room temperature and 300℃X when it is bent as it is. It shows the reduction rate of the load required to restore the material to its natural state after IHr heating and bend it again to the same radius of curvature, and the smaller the number, the better the heat resistance.

In addition, heat abrasion resistance indicates the specific wear amount determined by an ultra-high speed rapid abrasion tester.

The test conditions were: mating material JISSCM21 annealed material, wear distance 400 m, final load 6.8 kg, wear rate: 1
．． It is 34m/sec.

As shown in Table 2, the steel material A- of the present invention has better wear resistance, high temperature strength, and heat cracking resistance than conventional materials, and the oil ring of the present invention can reduce the ring weight and piston weight, and the energy generated by inertia. In addition to reducing losses, it has excellent airtightness and durability, and when used in pressure rings, there is no need for surface coating such as plating, making it possible to increase the output and speed of engines.

Although martensitic stainless steel without Mo, V, and Nb was used as a comparative material, it is clear from Table 2 that the effects of wear resistance and thermal damage resistance are improved due to the inclusion of Mo, V, and Nb. be.

Claims (1)

[Claims] 1. CO, 5-0.8%, Si 20.0%, Mn by weight
≦2.0%, Cr 10.0-15.5%, Mo 0
．． 2~. A steel piston ring material that is composed of 1.5% balance Fe and impurities and has excellent wear resistance and heat cracking resistance at the piston ring operating temperature. 2 C0.5-0.8% by weight, Si20.0%, Mn
2.0%, Cr 10.0-15.5%, Mo0.2
~1.5% and Wo, 3-3%, VO, 1-1.0%
A steel piston ring material containing one or more of the following, with the remainder being Fe and impurities, and having excellent wear resistance and heat resistance at the piston ring operating temperature. 3 C0.5-0.8% by weight, Si20.0%, Mn
≦0.2%, Cr 10.0-15.5% and Mo
0.2-1.5%, Wo, 3-3.0%, Vo, 1-
A steel piston ring containing one or more of 1.0% and 0.01-0.3% Nb, with the balance consisting of Fe and impurities, and has excellent wear resistance and heat cracking resistance at the operating temperature of the piston ring. Material.