JPS60208447A - Tough and hard sintered alloy - Google Patents

Abstract

PURPOSE:To increase the toughness of a sintered alloy, especially a carbide- base sintered alloy without reducing the hardness by restricting the amounts of Ca and S contained in the alloy as impurities. CONSTITUTION:An object of this invention is a sintered alloy consisting of 70- 97wt% hard phase of one or more kinds of components selected among the carbides and nitrides of the IVa, Va and VIa group metals in the periodic table and mutual solid solns. each consisting of such compounds and the balance binding phase of one or more kinds of iron groups metals with inevitable impurities. The amounts of Ca and/or S contained in the sintered alloy as impurities are restricted to <=0.01wt% Ca and/or <=0.008wt% S. The toughness of the sintered alloy can be increased without reducing the hardness which is a measure of wear resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Sandwich body 1] The present invention relates to a sintered alloy such as a cemented carbide and a cermet.

[Background technology]

In general, sintered alloys such as WCC cemented carbide and TIC base metal are used for cutting tools and wear-resistant tools because of their high hardness and excellent heat resistance. Among these cutting tools, they are widely used in applications where large impact forces are applied, such as large side forces of 1 m, and hobs, as well as drilling tools such as gun drills, gun reamers, end ors, and various drills. As the efficiency and automation of these cutting tools are promoted, there is an increasing demand for tools with stable tool life or high reliability. There are two main types of tool life: one is wear due to simple scraping, and the other is life due to chipping or chipping.

Of these, the tool life can generally be predicted from wear due to the clearance of the curved part, but the life expectancy caused by chipping or chipping cannot be predicted when it will occur during use of the tool, and there is a problem in that it lacks stability. . Simply increasing the amount of the binder phase or increasing the size of the condensed particles of the hard phase in order to improve the stability of the tool poses problems such as reduced wear resistance or plastic deformation.

[Purpose of the invention]

The present invention solves the above-mentioned problems, and aims to provide a strong sintered alloy in which toughness can be increased without reducing hardness, which is a measure of wear resistance.

[IHI indication of the invention]

The inventors of the present invention investigated the origin of fracture of a sintered base metal, especially a sintered base metal mainly composed of carbide, by observing fracture surfaces and using an X1M microanalyzer (Ca and/or S).
611 that the foreign matter contained in the was the origin of the destruction.
1, the present invention was completed.

The tough sintered alloy of the present invention is suitable for use in the periodic table IVa and Va.

■ At least one hard phase of group A metal carbides, carbides, and mutual solids thereof, with a weight of 70 to 97%, and the remainder;
Cm as an impurity of the sintered body consisting of at least 1 m of crystalline phase and unavoidable inclusions in the iron group metal is 0. p,,l,
% by weight or less and /1 or S is 0. , +OD 8% by weight
It is characterized by the following.

The strong sintered alloy of the present invention can reduce the transverse rupture strength without reducing the hardness in terms of the relationship between hardness and transverse rupture strength, which are typical characteristics of sintered alloys.1. -Specific ICC brightness, sintered base metal, sintered alloy mainly consisting of carbide in 48, carbide used as starting material, 8 and C&
S and Ca are also included in the iron group metals that were included in these starting materials ('a,
S generates coarse aggregates of CaS during the sintering process, which becomes the source of destruction after sintering, so Ca as an impurity,
Toughness is increased by limiting S.

At this time, S needs to be 0.0081Ji or less because it precipitates metal sulfides other than Ca8 and becomes a source of fracture. In addition, Ca becomes a CaS aggregate when S exists, and even if S does not exist, loose gold m is produced during the sintering process.
Since the carbide Vr becomes larger and this coarsened metal carbide also causes fracture, it is necessary to reduce the weight to 11.01% or less.

In particular, in the case of tungsten carbide with a hard phase of 2 μm or less, by limiting the amount of Ca to 4 or less and/or the S to 4 or less by weight, the hardness can be reduced. Transverse rupture strength can be significantly increased without any change.

In the method for producing the strong sintered alloy of the present invention, the Cm and S in the starting materials are strictly checked, and in the post-process, carbon or taracite is used in preliminary sintering and sintering in one machine. Although it is necessary to pay attention to Ca and S that are indirectly mixed in from carbon or graphite when using such materials, conventional powder metallurgy techniques can be fully used in other steps.

[Representative embodiment of the invention]

As the starting raw material powder, CaHl with an average particle size of 1.5 μm, 8 with an average particle size of 2 μm, and each a with an average particle size of 0.1 to 2 μm.
Powder (Ca is 0.01 weight or less, S is o, o o a
vehicle volume - strictly adjusted as below)
&V amount, and the powder was sonic crushed in a ball bowl for 72 hours, pressed at a pressure of 1 ton/cd to form a green compact, and then the green compact was crushed under a pressure of 5xio4inH1J.
Sintered alloy samples 1 to 6 of the present invention and comparative products 7 to 9 were manufactured by sintering in a vacuum at a temperature of 1400° C. for a holding time of 1 hour. Sample 1 of the present invention obtained as a result
6 and comparative products 7 to 9, the hardness and transverse rupture strength were measured.

These results are shown in Table 1.

[Industrial applicability]

As a result, the strong sintered alloy of the present invention has a high transverse rupture strength while maintaining conventional hardness, so it can be used in punches, dies, etc.
Cutting tools such as # cutting tools, Slitsume-1 cutting blade, etc.
Machine parts jigs and tools such as guide bushes, rolls, and gauges, wear-resistant tools such as pulp and mechanical seals, as well as turning tools, price tools with high impact, and low-speed heavy cutting such as end-rules, reamers, drills, etc. It is an industrially useful tool material that can be used as a cutting tool such as a drilling tool, and may also be used as a base material for various types of slightly sintered alloys.

Claims (2)

[Claims] (1) Among the carbides, nitrides, and mutual solids of metals of groups IVa, Va, and Via of the periodic table, at least 1 hard phase of 70 to 97 layers remains, and iron group metals remain. In an mM gold alloy consisting of at least 11m of binder phase and unavoidable impurities, Ca (calcium) as an impurity is 0.
lIIIKM 96 or less and/or S (sulfur) +1
．． A strong sintered alloy characterized by having a toughness of 008 k jlt or less. (2) The upper Re hard phase is mainly composed of tungsten carbide with an average grain size of 2 μm or less.
'f Tough sintered alloy O according to claim 46 if item