JPS6237356A - Manufacture of co base alloy member superior in wear resistance - Google Patents

Abstract

PURPOSE:To manufacture the titled member, by soln. heat treating Co base alloy member contg. specified compsn. quantities of C, W, Mo, Cr, then providing surface strain by shot blasting, and applying a suitable aging treatment thereto. CONSTITUTION:Co base alloy member having a compsn. composed of, by weight 0.05-2% C, 2-20% one or more kinds of W or Mo, 15-35% Cr further if necessary 1-25% of one or more kinds of Ni or Fe and the balance Co with inevitable impurities is soln. heat treated under conventional condition. Next, the number is shot blasted to provide surface strain, successively aging treated at 700-1,000 deg.C. In this way, the structure of at least surface part is made to that in which primary and secondary carbides are dispersed in matrix and grain boundary respectively, further fine secondary carbides having <=1mum diameter are dispersed in grain, hardness is improved and wear resistance is remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a Co-based alloy member having excellent wear resistance and heat resistance.

[Conventional technology]

In general, excellent wear resistance and heat resistance are required for manufacturing chain saw guides, saw teeth for woodworking, light metal and alloy cutting, steam turbine blades, various shaft parts, valve parts, etc. Therefore, various Co-based alloys are used.

Also, one of these various Co-based alloys is 1% by weight (hereinafter, ``chi'' indicates % by weight).

C: 0.05-2%.

One or two of W and Mo: 2-20%1 Cr: 15-35%, Contains and further if necessary.

One or two of N1 and Fe: 1 to 25 chi.

Co-based alloys are widely known which have a composition containing CO and the remainder consisting of CO and unavoidable impurities.

For example, when these Co-based alloy members are plate materials, 1 the ingot after casting is usually subjected to 1-blunt forging, blooming rolling, and further hot rolling or cold rolling to obtain a plate thickness of approximately 1 to 4 B. It is manufactured by subjecting this plate material to solution treatment at a temperature of 1100 to 1250°C, and is put into practical use in this state.

[Problem that the invention seeks to solve]

However, in recent years, there has been a demand for higher speed and higher performance in the above application fields, and with this,
It is desired to further improve the wear resistance of the above-mentioned conventional Co-based alloy members.

[Failure to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors focused on the above-mentioned conventional COi alloy member and conducted research to further improve the wear resistance of the above-mentioned conventional COi alloy member.
After solution treatment, the O-based alloy member has a structure in which primary carbides are dispersed in the matrix and secondary carbides are precipitated only at the grain boundaries. 700-100 after applying surface strain by shot blasting
When aging treatment is carried out at a temperature of 0°C, in the resulting Co-based alloy member, primary carbides exist in the matrix and secondary carbides are dispersed in the grain boundaries, but especially in the surface area. It now has a structure in which secondary carbides are precipitated within the crystal grains, and since the secondary carbides precipitated within the crystal grains are fine with a diameter of 1 μm or less, the hardness within one crystal grain is lower than that of the conventional one. Co-based alloy plate material has a Vickers hardness of approximately 2
They obtained the knowledge that the wear resistance was improved from 50 to about 300 per day, resulting in a significant improvement in wear resistance.

Therefore, this invention has been made based on the above findings.

C: 0.05 to 2 inches.

One or two of W and Mo: 2 to 20.

Cr: 15-35%.

Contains, and if necessary, One or two of N1 and Fe = 1 to 25.

A Co-based alloy member containing CO and unavoidable impurities as a residue and subjected to solution treatment under normal conditions was heated at 700 to 1000°C with surface strain imparted by shot blasting. By performing aging treatment at a temperature of , primary carbides are dispersed in the matrix, secondary carbides are dispersed in the grain boundaries, and secondary carbides with a diameter of 1 μm or less are further dispersed in the crystal grains, at least in the surface area. It has an organized structure.

The present invention is characterized by a method for manufacturing a Co-based alloy member with extremely high wear resistance.

Next, in the method of the present invention, the reason why the composition and aging treatment temperature of the Co-based alloy member are limited as described above will be explained.

A. Component composition (a) C The C component has the effect of forming carbide and improving wear resistance, but if its content is less than 0.05%, especially 2
Precipitation of secondary carbides becomes insufficient, making it impossible to secure the desired wear resistance.On the other hand, if the content exceeds 2.
Since plastic working becomes difficult, its content is reduced to 0.05.
It was set as ~2chi.

(b) w and Mo These components have the effect of forming a solid solution in the base material and strengthening it, as well as forming carbides and improving wear resistance. If the content is less than 20%, the desired effect cannot be obtained; on the other hand, if the content exceeds 20%,
In addition to decreasing plastic workability, the plate material also tends to become brittle, so the content should be reduced to 2 to 20%.
%.

(c) Cr The Cr component has the effect of improving heat resistance by forming a solid solution in the base material, as well as improving wear resistance by forming carbide, but if its content is less than 15%, the desired effect may not be achieved. On the other hand, if the content exceeds 35%, brittle phases such as σ phase will appear and plastic workability and ductility will decrease. 15~
It was set at 35chi.

(d) Ni and Fe These components dissolve in solid solution in the base material and have the effect of improving ductility and plastic workability, so they may be included as necessary when these properties are particularly required. If the content is less than 1 inch, the desired effect of improving the above action cannot be obtained, while if the content exceeds 25%, the wear resistance will be significantly lowered, so the content should be reduced from 1 to 25%. It was determined that

If the temperature of B9 aged treated coal is less than 700°C, fine secondary carbides cannot be produced sufficiently within the crystal grains, especially in the surface area where surface strain has been applied, while on the other hand, if the temperature exceeds 1000°C, Since both the primary and secondary carbides become coarse and the desired wear resistance cannot be ensured, the temperature is set at 700 to 1000°C.

EXAMPLES Next, the method of the present invention will be specifically explained with examples.

Molten CO-based alloys having the respective compositions shown in Table 1 were prepared using a normal melting method, and cast to diameter: 9.
0Bφ×Length: After making an ingot with dimensions of 350ffjl, this ingot was
A hot-rolled plate with a thickness of 211 was obtained by hot forging at a temperature of 1200°C and hot rolling at a temperature of 1200 to 1000°C, and then held at a temperature of 1200°C for 0.5 hours. After that, solution treatment was performed under air-cooling conditions, and then the plate material with the dimensions of width: 100 mm x thickness: 2 mm x length: 200 mm after solution treatment was blasted using a shot blasting machine (diameter: 2 mm).
After applying surface strain by shot blasting for the time shown in Table 1, aging treatment was carried out in the atmosphere at the temperature also shown in Table 1 (holding for 1 hour). Then, methods 1 to 22 of the present invention were carried out by performing air cooling).

Next, the plate materials (
An Okoshi type abrasion tester was used for the plate material K (hereinafter referred to as the present invention plate material) and the plate material before shot blasting, that is, the plate material after solution treatment (hereinafter referred to as conventional plate material).

Mating material: JIS-8UJ-2 (hardness: HRC60)
.

Load: 18.2kg, Friction speed: 0.119m/crown.

Friction distance: 100m, Lubricant: Not used.

A wear test was conducted under the following conditions, and the specific wear amount was measured and shown in Table 1.

In addition, when the surface structure of these plates was observed using a metallurgical microscope, it was found that the plates of the present invention had primary carbides dispersed in the matrix, and secondary carbides dispersed in the grain boundaries (7, and the diameter 1 Conventional plate material has a structure in which fine secondary carbides of 21 μm or less are precipitated within the crystal grains.
In all cases, primary carbides were dispersed in the matrix, but secondary carbides were precipitated only at grain boundaries.

〔Effect of the invention〕

From the results shown in Table 1, it can be concluded that: 1) The plate materials of the present invention manufactured by the method of the present invention have a structure in which fine secondary carbides are precipitated within the crystal grains, especially on the surface;
It is clear that this material exhibits superior wear resistance compared to the conventional sheet material as solution-treated, which has a structure in which subcarbides are precipitated only at grain boundaries.

As mentioned above, according to the method of the present invention, a diameter of 21 μm
It is possible to produce a Co-based alloy member having a surface structure in which the following fine secondary carbides are precipitated within the crystal grains, and the hardness of the crystal grains themselves is significantly improved by the precipitation of the secondary carbides. So.

The Co-based alloy member exhibits industrially useful effects such as extremely excellent wear resistance.

Claims (2)

[Claims] (1) A composition containing C: 0.05-2%, one or two of W and Mo: 2-20%, Cr: 15-35%, and the remainder consisting of Co and inevitable impurities ( (wt% or more) is subjected to solution treatment under normal conditions, then subjected to surface strain by shot blasting, and subsequently subjected to aging treatment at a temperature of 700 to 1000°C. As a result, the structure of at least the surface part is defined as a structure in which primary carbides are dispersed in the matrix, secondary carbides are dispersed in the grain boundaries, and secondary carbides with a diameter of 1 μm or less are dispersed in the crystal grains. A method for producing a Co-based alloy member having excellent wear resistance. (2) Contains C: 0.05-2%, one or two of W and Mo: 2-20%, Cr: 15-35%, and further contains one of Ni and Fe. or type 2: 1 to 25%, and the remainder is Co and unavoidable impurities (weight%). After solution treatment is carried out under normal conditions, this is shot. By imparting surface strain by blasting and subsequently aging at a temperature of 700 to 1000°C, the structure at least on the surface can be changed to include primary carbides in the matrix and secondary carbides in the grain boundaries. A method for producing a Co-based alloy member with excellent wear resistance, characterized by forming a structure in which carbides are dispersed and secondary carbides with a diameter of 1 μm or less are dispersed within crystal grains.