JPH01104407A - Wear resistant parts - 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 [Field of Industrial Application] The present invention relates to a wear-resistant member having high hardness and lubricity that is useful as rolling rolls, guide rollers, etc.

[Conventional technology]

Conventionally, high C and high Cr cast iron, such as 13Cr wear-resistant cast iron (C:2
．． 4-3.6%, Si: 1% or less, Cr: 14-2
8%, Mo: 3% or less, Ni: 1.5% or less, Cu
: 1.2% or less, balance Fe), or 27Cr wear-resistant cast iron (C: 2.3-2.9%, Si: 0.5-1.
5%, Mn: 0.5-1.5%, Cr: 24-28%,
Ni: 0.2% or less, Mo: 1.2% or less, balance Fe), etc. have been used. These high C and high Cr cast irons have high hardness due to austenite and martensite bases and exhibit relatively good wear resistance.

[Problem that the invention seeks to solve]

However, if the component is thick or large, the cooling solidification rate during casting will be slow, making it difficult to secure austenite and martensite bases, resulting in insufficient hardness and resulting lack of wear resistance. cause In addition, even if it has a martensite base with high hardness, it cannot necessarily guarantee sufficient wear resistance depending on the usage conditions.Furthermore, hard wear-resistant materials generally have poor toughness, so they are susceptible to mechanical shock. When a member is used for a specific purpose, it is often subject to design restrictions.

In view of the above, it is an object of the present invention to provide a wear-resistant member that has higher wear resistance and toughness than conventional high-C, high-Cr cast iron.

[Means and effects for solving the problems] The wear-resistant member of the present invention has a composite structure in which 1 to 20% by weight of boron carbide-stabilized graphite grains are mixed as a dispersed phase in a high Cr stainless cast steel matrix. It is characterized by covering the surface of the member with a build-up material (hereinafter referred to as "composite build-up layer").

The high Cr stainless cast steel that is the matrix of the composite overlay layer that covers the surface of the wear-resistant member of the present invention has a mainly martensitic structure and is itself highly hard. The composite overlay layer has a hardness that exceeds that of conventional high-C, high-Cr cast iron members due to the hard matrix and the dispersion-strengthening effect of the graphite grains mixed therein.
This process provides extremely good wear resistance due to the presence of graphite grains as a dispersed phase in the matrix, which provides appropriate lubricity.

The composite build-up layer in the wear-resistant member of the present invention is composed of powder of high Cr cast steel serving as a matrix and boron carbide (B, C).
A mixture with stabilized graphite grains is used as an overlay material, and it is formed on the surface of a base material by a weld overlay method, a thermal spraying method, etc.

84C stabilized graphite grains are graphite with B
Graphite is chemically and physically stabilized by containing about 5% by weight or more (usually 5 to 50% by weight) of aC. In the present invention, the reason for using 84C stabilized graphite grains is that graphite grains deteriorate and wear out (decomposition, oxidation, dissolution into matrix metal, etc.) during the process of forming a composite overlay layer by welding overlay method etc. ) to prevent this. If normal graphite grains are used, a considerable amount of the graphite grains will deteriorate and be consumed in the build-up layer formation process, but by using B and C stabilized graphite grains, such inconveniences will not occur and the graphite grains can be used in places. It becomes possible to form a built-up layer having a composite structure of the same period.

The proportion (mixed proportion) of B and C stabilized graphite grains in the composite structure of the overlay layer is 1 to 20% by weight. 1
The lower limit of weight % is that if it is less than that, B, C
This is because the dispersion effect of stabilized graphite grains is insufficient in lubricity and hardness, and on the other hand, the reason why the upper limit is set at 20% by weight is that, although lubricity increases if it exceeds 20%, the lubricity and hardness of the overlay layer increase. This is because it causes a lack of toughness. Although the particle size of the stabilized graphite particles B and C is not particularly limited, it is about 20
A range of 200 μm is suitable.

On the other hand, the reason why high Cr stainless cast steel is used as the matrix metal is to obtain a strong and hard martensite base, and examples of preferable high Cr stainless cast steel include 13Cr stainless cast steel (C: 0.01 ~0.5%
, Si: 2% or less, Mn: 2% or less, Cr: 11~
15%, Ni: 1% or less, MO: 0 or 5% or less, balance Fe), 18Cr stainless steel cast steel (C: 0.01-1.5%
, Si: 2% or less, Mn: 2% or less, Cr: 15-20
%, Ni: 5% or less, MO: 0 or 5% or less, balance F
e), 27Cr stainless steel cast steel (C: 0.01~3%, St
: 2% or less, Mn: 2% or less, Cr: 22-30%, N
i: 5% or less, MO: 0 or 5% or less, balance Fe), etc.

The material of the base material covered with the composite overlay layer can be freely selected depending on the intended use and required performance of the wear-resistant member. By combining the base material with a composite overlay layer and applying overlay to the minimum area of the base material surface required for design, the brittleness that is common to wear-resistant high hardness materials can be eliminated. ,
A wear-resistant member with stable strength can be obtained.

[Example] 13Cr stainless steel cast steel powder (C: 0.2%, Si:
0.6%, Mn: 0.6%, Cr: 13%, Ni: 0.
A mixed powder of 3% Mo, 1% Mo, balance Fe) and B, C stabilized graphite powder (B4C: graphite = 1:1, weight ratio) was used as the overlay material, and the base material (carbon steel) was The grain size of the B and C stabilized graphite grains, which were welded overlay on the surface to form a composite overlay layer with a layer thickness of about 10IIIm, was 50 μm, and the mixed ratio was 10% by weight.

The mechanical properties and abrasion resistance of the above sample material (as welded product) were evaluated, and the results shown in Table 1 were obtained.

Regarding wear resistance, the specific wear amount was determined by the roll contact wear test method, and the conventional material 13Cr cast iron (C:
2.9%, Cr: 13.2%) and 27Cr cast iron CC: 2.4%, Cr: 26.5%). As shown in Table 1, the invention examples have high hardness and strength, excellent wear resistance, and good toughness.

Table 1 [Effects of the Invention] The wear-resistant member of the present invention has high hardness and
It has wear resistance that greatly exceeds cast iron materials, and also has good toughness. In addition, since the material of the base material covered with the composite overlay layer can be freely selected, the combination with the base material can be used to
It can also have the strength required as a structural member depending on the conditions of use. Therefore, the wear-resistant member of the present invention is useful as a rolling roll, a guide roller, etc., and is effective in improving the durability of the member and reducing maintenance.

Claims (1)

[Claims] (1) A wear-resistant member in which the surface of the member is coated with a built-up layer having a composite structure in which 1 to 20% by weight of boron carbide-stabilized graphite grains are mixed as a dispersed phase in a high Cr stainless cast steel matrix.