JPH06172915A - Wear resistant alloy powder, wear resistant composite member using the same and production thereof - Google Patents

Abstract

PURPOSE:To obtain alloy powder for enhancing the wear resistance of an iron- based member and to provide wear resistant composite member by using the powder. CONSTITUTION:The objective alloy powder has a chemical compsn. consisting of, by weight, 2-4% C, <=2% Si, 1-4% Ni, 2-30% Cr, 2-10% V, 5-15% W, 3-10% Mo, 1-15% Co and the balance Fe with inevitable impurities. This alloy powder is simultaneously subjected to sintering by hot isostatic pressing and diffusion bonding to carbon steel or low-alloy steel to obtain the objective wear resistant composite member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy powder used for improving the wear resistance of an iron-based member, a wear resistant member using the same, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, in order to improve the wear resistance of iron-making machine parts and the like, in addition to improving the material itself of the member,
Hardened layers are formed by various fusion welding methods, and the surfaces of members are compounded. In addition, in some cases, it is possible to manufacture a composite member using a commercially available powder material for plasma spraying by using pressure bonding of powder material by a hot isostatic pressing (hereinafter referred to as HIP) method and diffusion bonding technology. Has been done.

[0003]

However, in the fusion welding method, when the amounts of various additive elements are increased to form a high alloy,
It became difficult to manufacture the welding material itself and welding work, and from these two aspects, there was a limit to the range of alloy element components that can be added. In addition, in order to prolong the service life of mechanical parts, a method of increasing the thickness of the surface hardened layer is often adopted,
Generally, a welding material having a higher hardness is more difficult to form a multi-layer deposit, and even if it is possible to perform work, very strict management such as work conditions is often required. Also, in such thick-walled construction, that is, in the multi-layered construction, the welding construction takes a long time,
There are also many problems regarding worker health management and product cost.

Furthermore, in overlay welding, the structure and hardness distribution of the weld bead are not always constant due to the heat history of the welding process, etc. Therefore, there is a problem that a bead mark is generated and transferred to a product which is a mating material. Occurs. In the plasma spraying method, it is possible to apply even a relatively high alloy, and therefore it is possible to form a surface layer having a high hardness, but in these cases, in general, it is impossible to form a multi-layer deposit,
Only a thin hardened layer is formed on the surface.

An object of the present invention is to obtain an alloy powder that solves the above-mentioned problems of the prior art, and further to provide a wear resistant composite member using the alloy powder and a method for producing the same. .

[0006]

In order to achieve the above object, in the wear-resistant alloy powder of the present invention, the chemical composition is% by weight, C2-4%, Si2% or less, Ni1-4%, Cr.
2-30%, V2-10%, W5-15%, Mo3-1
It is composed of 0%, Co 1 to 15%, balance Fe and unavoidable impurities.

The wear-resistant composite member of the present invention is made of the above alloy powder, which is sintered by the HIP method and is diffusion bonded to carbon steel or low alloy steel.

Further, the above-mentioned composite member has 1000
It is preferable that the heat treatment is performed at a temperature of ℃ or less because the wear resistance is further improved.

The chemical components of the alloy powder of the present invention will be described below. In the following, all% means% by weight. C forms a solid solution in the matrix, and increases the hardness of the sintered alloy by forming a carbide by combining with V, Cr, and W. When the amount of C is less than 2%, the amount of carbides is small and the wear resistance is insufficient, and the effect of highly alloying the sintered alloy cannot be sufficiently obtained. On the other hand, if it exceeds 4%, the toughness decreases due to coarsening of V and W carbides, and the liquidus temperature decreases due to solid solution in the matrix, making it difficult to perform stable construction in consideration of the formation of carbides.

Si is effective as a deoxidizing agent in the production of powder materials, but if the amount is increased, the matrix becomes brittle, so the upper limit was made 2%, but it is desirable to make it 1.0% or less if possible. .

Ni increases the matrix hardness, but reduces the high temperature stability of the structure. Therefore, the range for imparting good hardness and high temperature stability is set to 1 to 4%.

[0012] Cr combines with C to form a Cr carbide, which improves the wear resistance and also improves the corrosion resistance of the matrix. However, if it is less than 2%, the amount of the carbide is small and sufficient wear resistance cannot be expected. On the other hand, if it exceeds 15%, the effect on room temperature hardness disappears, but the amount of Cr dissolved in the matrix increases,
Corrosion resistance and high temperature hardness are further significantly improved. Therefore, especially when used at high temperatures, if the content is less than 15%, these effects are small, and if the content exceeds 30%, the melting point of the alloy becomes high and the sinterability deteriorates.

V combines with C to form V carbides.
V carbides have a high altitude and are precipitated in a spherical shape to improve the toughness, but if the content is less than 2%, the wear resistance is insufficient, and the amount of C dissolved in the matrix increases. It changes a lot. If it exceeds 10%, the amount of V dissolved in the matrix increases and the hardenability deteriorates. Further, V is very easily oxidized, and the corrosion resistance of the matrix decreases.

W combines with C to form a carbide and combines with Mo to form an intermetallic compound, which contributes to wear resistance. The effect increases as the added amount increases, but if it is contained in a large amount, mechanical properties such as toughness deteriorate due to coarsening of precipitated carbide. Therefore, the range having good wear resistance and crack resistance is limited to 5 to 15%.

Mo enters the carbide and is effective in increasing the carbide height and at the same time improving the temper softening resistance. Further, it combines with W to form an intermetallic compound, which contributes to wear resistance. However, if the content is less than 3%, such an effect does not occur, while if it exceeds 10%, the effect is almost saturated.

[0016] Co dissolves mostly in the matrix and contributes to the improvement of heat resistance (high temperature hardness) and tempering hardness, but if it is less than 1%, this effect is not sufficient, while if it exceeds 15%, it is The effect is almost saturated.

[0017]

In the powder sintering by the HIP method, generally, without causing the appearance of a liquid phase, the powder is sintered by solid phase diffusion bonding, and the diffusion bonding to the member to be the base material is also performed at the same time. For this reason, the range of alloy components that can be applied is very wide, and the applied material itself is manufactured by a rapid solidification method such as atomization when manufacturing powder, so that high alloying is easy.

It is also possible to promote the growth of precipitated carbide and the like in the matrix by intentionally causing a liquid phase to partially appear during powder sintering. Excellent wear resistance can be exhibited by the effect of the carbides grown in this way. In this case, since the existence of the liquid phase is a local minute region, the effect is exerted mainly only in the growth of carbides and precipitates, not in the entire melt-solidification reaction in which the crystal grains become coarse. . In addition, during sintering and subsequent cooling in the high temperature range, high isotropic pressure is applied from the surroundings, so defects such as shrinkage cavities and cracks that generally occur during casting or fusion welding are less likely to occur and sound A sintered layer is obtained.

In either case, the obtained sintered layer has a fine and uniform structure over the entire area, and its hardness has a uniform value in all directions, and it has good wear resistance and corrosion resistance, and has a sufficient surface area. The thickness of the composite layer can be easily obtained.

High-speed steel materials, whether powder or steel, can be hardened and tempered to obtain high hardness. In this case, the quenching temperature is generally as high as 1000 ° C or more, and heat treatment is special. The difficulty of becoming
There are problems such as high cost. However, with the alloy powder according to the present invention, it is possible to exhibit high-level properties by a general heat treatment at a lower temperature.

[0021]

EXAMPLES Examples of the present invention will be described below together with comparative examples. Table 1 shows the chemical composition and hardness of the alloys of the present invention and comparative alloys. In Table 1, HIP means hot isostatic pressing. In addition, No. 1-No. No. 9 is the alloy of the present invention.
10-No. 14 is a comparative alloy.

[0022]

[Table 1]

In the document describing the chemical formula, etc., [A] is as
-Normal temperature hardness in HIP (without heat treatment), [B] is a
High temperature hardness at 800 ° C in s-HIP (without heat treatment), [C] is room temperature hardness after tempering at 500 ° C, [D]
Indicates the room temperature hardness after quenching at 900 ° C. In addition, * indicates the occurrence of cracking. (1) No. 1 in Table 1 Using the alloy powder of No. 3, a steel bar rolling roll was manufactured under HIP treatment conditions of 1200 ° C., 1000 kg / cm ² , and 2 hr. 1 sintered layer in matrix
It exhibited a structure in which spherical carbides of 0 to 30 μm were uniformly dispersed.

(2) No. 1 in Table 1 Using the alloy powder of No. 6, HIP treatment conditions, 1200 ° C, 1000 kg / cm ² , 2
A roll for rolling steel bars was manufactured at hr. The sintered layer had a structure in which 10 to 30 μm spherical carbides were uniformly dispersed in the matrix.

(3) No. 1 in Table 1 Using 9 alloy powder,
HIP treatment condition, 1200 ° C, 1000kg / cm ² , 2hr
In the above, a steel bar rolling roll was manufactured. The sintered layer had a structure in which fine carbides were uniformly dispersed in the matrix.

(4) No. 1 in Table 1 Using the alloy powder of No. 3, HIP treatment conditions, 1100 ° C., 1000 kg / cm ² , 2
A roll for rolling steel bars was manufactured at hr. The sintered layer had a structure in which fine carbides were uniformly dispersed in the matrix.

In any of the above-mentioned Examples (1) to (4), the bar rolling roll has an outer diameter of 100 mm and a length of 100 mm.
The shape of the roll was R30 on the outer circumference, and S35C was used as the base material. For this, a powder sintered layer having a thickness of 10 mm was formed from the roll surface. In each case, no defects were found in the sintered layer after as-HIP and after the heat treatment, and a sintered layer having a hardness similar to that shown in Table 1 was obtained.

These HIP rolls were found to have a life extension of 10 times or more as compared with alloy chilled rolls. Further, in comparison with the self-fluxing alloy sprayed roll, a life extension of 6 times or more was recognized in comparison with wear resistance, and further, when the effect of increasing the thickness of the hardened layer was also compared, the product life was 10 The life extension was more than doubled. Needless to say, of course, the only restriction on the size of the applied parts is the size of the HIP furnace to be processed, and it can be applied to larger members. Also, the thickness of the sintered layer on the surface can be arbitrarily set from several mm to several tens of mm.

[0029]

As described above, according to the wear-resistant alloy powder of the present invention, the sintered member can be easily sintered by hot isostatic pressing. Has a high hardness and abundant wear resistance. Also, a composite member obtained by diffusing a sintered body of this alloy powder into carbon steel or low alloy steel is
Since it can be easily manufactured and the sintered member has high wear resistance, its life can be greatly extended when it is used as a rolling roll or the like. The hardness of this composite member is 100
By heat treatment at a temperature of 0 ° C. or lower, as shown in Table 1, the heat resistance can be further improved, and thus the wear resistance can be improved.

Claims (3)

[Claims] 1. The chemical component is, by weight, C2-4%, Si
2% or less, Ni1-4%, Cr2-30%, V2-10
%, W5-15%, Mo3-10%, Co1-15%,
A wear-resistant alloy powder comprising the balance Fe and inevitable impurities. 2. The alloy powder according to claim 1, wherein the alloy powder is sintered by hot isostatic pressing and diffusion bonded to carbon steel or low alloy steel. Wear resistant composite member. 3. The composite member according to claim 2,
A method for producing a wear-resistant composite member, characterized by performing heat treatment at a temperature of ℃ or less.