JPH0499245A - Sintered hard alloy - Google Patents

Abstract

PURPOSE:To obtain a sintered alloy for tools having excellent wear resistance by sintering the fine powder of the carbon nitrides of specified metals having high hardness with Fe series metals contg. Cr as a binder. CONSTITUTION:By weight 70 to 99% fine powder with <=3mum particle diameter of the carbon nitrides having high hardness of Ti in group Na metals, Ta, Nb and V in group V metals and W in group VI a metals or the like in a periodic table is mixed with 1 to 30% powder of Fe group metals such as Fe, Ni and Co contg. 1 to 30% Cr as a binder at the time of sintering, and this mixed powder is compacted and is thereafter sintered. In this case, the content of N in the sintered alloy is regulated to the range of 0.02 to 0.4%. The sintered hard alloy having high hardness and suitable for a forming die used for the deep drawing of a steel sheet for can-making and for tools requiring high wear resistance such as cutting tools can be obtd.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to cemented carbide, and in particular, to highly wear-resistant materials such as forming dies and cutting tools used in deep drawing of steel plates for can manufacturing. The present invention relates to cemented carbide suitable for tools that require high properties.

[Prior art] A typical industrially produced cemented carbide is one whose main component is fine powder of tungsten carbide (WC), with iron group metals such as cobalt (CO) as a binder phase. It is a sintered product, and has traditionally been used as a plastic working tool.
C--Co alloys are commonly used. However, in forming dies for deep drawing, which are used under harsh conditions with a high drawing ratio and where the contact surface between the workpiece and the tool is heated due to frictional heat, the contact between the tool and the workpiece is In WC-Co cemented carbide, crimping and welding occur on the tool surface due to the frictional heat generated during the process and wear of the tool, which causes galling of the tool and shortens the tool life.

Therefore, in order to improve these problems, the hard phase is mainly composed of WC, and tantalum carbide (T) is added to this.
Cemented carbide for plastic working, in which titanium carbide (T i C) and titanium carbide (T i C) are added, and chromium or chromium compounds are solidly dissolved in the binder phase consisting of iron group metals, has been developed, for example, by Japanese Patent Publication No. 63-15.
This is proposed in Japanese Patent No. 980. The cemented carbide described in the publication improves the crimp resistance and welding resistance of tools by taking advantage of the low affinity of TaC and TiC for the workpiece material, and by including chromium element in the binder phase. , which aims to improve alloy properties at high temperatures.

[Problem to be solved by the invention] However, especially in can making processing where tin-plated steel plates are deep drawn, there is a desire to further extend tool life and reduce manufacturing costs under harsh processing conditions. Therefore, the challenge was to develop a cemented carbide with even higher wear resistance than the conventional cemented carbide mentioned above.

[Means for Solving the Problems] In order to solve the above problems, the cemented carbide of the present invention comprises a carbonitride of at least one element belonging to Group IVa, Group Va, or Group VIa of the periodic table. It contains a hard phase of not less than 99% by weight and a binder phase of not less than 1% and not more than 30% by weight, which is made of an alloy with iron group metal chromium.

The content of chromium element in the binder phase is 1 for the total binder phase.
The nitrogen content in the entire alloy is 0.05 to 0.4 weight %.

[Function] The composition of the cemented carbide of the present invention is limited as described above because
Due to the following reasons.

First, the content of the hard phase was set to 70% by weight or more because 7
This is because if it is less than 0% by weight, the content ratio of the hard phase becomes relatively too low, the hardness decreases, and the desired wear resistance cannot be obtained. In addition, the content of the hard phase is 99% by weight.
The reason why it is set below is that if the content exceeds 99% by weight, the content of the binder phase becomes less than 1% by weight, making it impossible to form a defect-free and high-quality alloy.

In addition, the content of chromium in the binder phase is 1% relative to the total binder phase.
The reason why the range is from 1% to 30% by weight is that if it is less than 1% by weight, the effect of improving the alloy properties at high temperatures by adding chromium is not sufficient, and if it exceeds 30% by weight, the toughness of the binder phase decreases.

Furthermore, the nitrogen content in the entire alloy is 0.05% by weight.
The reason why the nitrogen content is 0.4% by weight or less is that the welding resistance is improved by containing nitrogen in an amount of 0.05% by weight or more.
If it is less than 0.05% by weight, the effect will not be sufficient, and if it exceeds 0.4% by weight, the sinterability will deteriorate, defects such as pinholes will increase, and the strength will decrease on the contrary.

Note that the particle size of the carbonitride in the hard phase is preferably 3 μm or less. This is because when the particle size of the hard phase exceeds 3 μm, the hardness of the alloy decreases and the wear resistance of the tool deteriorates, and the hard phase becomes even larger than when the particle size of the hard phase exceeds 3 μm for the same amount of binder phase. If the stress is concentrated in that area,
This is because it reduces the toughness of the alloy and, as a result, reduces the life of the tool.

In addition, as the plasticity of the hard phase, at least tungsten,
Preferably, carbonitrides of titanium, tantalum, niobium and vanadium are included. This is IVa, Va, VI
Among group A carbonitrides, WC-C, which is a conventional common cemented carbide, has good wettability with iron group metals and Cr.
This is because by including carbonitrides such as Ti and Ta rather than the O alloy, the compatibility with the workpiece is lowered and the welding resistance and pressure bonding resistance are improved.

[Example] The present invention will be specifically explained below according to examples.

Cemented carbide alloys having nine types of component compositions shown in Table 1 were prepared, and the following two types of tool durability tests were conducted on each of these cemented carbide alloys. Note that the numerical values marked with * in Table 1 are outside the scope of the present invention. Therefore, these 9
Among cemented carbide alloys with different compositions, composition No. 2. 7
．． Three types of No. 8 are the products of the present invention, and the other six types are all comparative products.

(Hereinafter, blank spaces) Table 1 * indicates that the value is outside the scope of the present invention.

(Tool Durability Test 1) In order to evaluate the wear resistance when the cemented carbide according to the present invention is used as a mold for deep drawing (ironing), the cemented carbide of nine types of composition shown in Table 1 was tested. A die for deep drawing shown in Table 2 was formed, and a can making test was conducted under the conditions shown in Table 2.

Based on the case where This is expressed as a ratio of 1.

(More than 1,000 [F]) Table 2 The results of this machining test are shown in the "Results of Tool Durability Test 1" column of Table 3. The values shown in this column are the relative ratio of tool life, that is, the ratio of the number of cans molded before the die wears out and becomes unusable. As is clear from the results in Table 3, when the product of the present invention is used as a mold for deep drawing, it can be seen that the life is significantly extended compared to the comparative mold. Among these, the service life of the cemented carbide of composition No. 2, which is a product of the present invention, is significantly extended.

The reason for this is that the hard phases of WClTiC, TaC, and NbC are finely dispersed to improve wear resistance, and nitrogen is contained to improve pressure adhesion resistance and welding resistance with the workpiece. The reason why the life of the cemented carbide with composition No. 8, which is the product of the present invention, is relatively small is considered to be because the grain size of the hard phase is outside the preferred range of 3 μm or less.

(Tool durability test 2) Next, in order to evaluate the wear resistance when the cemented carbide according to the present invention is used as a cutting tool, seven types of compositions other than No. 4.6 were tested from among the compositions shown in Table 1. A tool tip was made from cemented carbide having the composition, and a cutting test was conducted under the conditions shown in Table 4.

Table 4 The results of this cutting test are shown in Table 3 above.
The results are as shown in the "Results" column. Comparing the values in this column, it can be seen that the products of the present invention are superior to the comparative products also in terms of wear resistance as a cutting tool. In addition,
Among the products of the present invention, the improvement in wear resistance is small in the case of the cemented carbide with composition No. 8, which is considered to be because the grain size of the hard phase exceeds 3 μm in this case as well. In addition, the reason why the amount of flank wear is large in the case of the comparative cemented carbide with composition No. 19 is that the analytical value of the nitrogen content in the entire alloy is 0, and the hard phase is less than 70% by weight. , furthermore, this hard phase consists only of WC, Tic, TaC,
This is thought to be because it does not contain NbC or the like.

[Effects of the Invention] As described above, according to the present invention, 70% by weight or more
By containing a hard phase of less than % by weight, a certain amount of chromium in the binder phase, and a certain amount of nitrogen in the entire alloy, performance such as welding resistance as a tool is improved, and deep drawing is possible. When used as a tool for either machining or cutting, the tool life can be significantly extended, and machining costs can be reduced in can manufacturing by deep drawing, cutting of steel materials, etc.

Claims (3)

[Claims] (1) A hard phase consisting of a carbonitride of at least one element belonging to Group IVa, Group Va, or Group VIa of the periodic table, with an amount of 70% to 99% by weight, an iron group metal, and chromium. consisting of an alloy, 1% by weight or more 30
% by weight or less of a binder phase, the content of the chromium element in the binder phase is 1% by weight or more and 30% by weight or less based on the total binder phase, and the nitrogen content in the entire alloy is 0.0% by weight or less. 02% by weight or more 0.4% by weight
A cemented carbide characterized by: (2) The cemented carbide according to claim 1, wherein the carbonitride of the hard phase has a grain size of 3 μm or less. (3) The cemented carbide according to claim 1, wherein the hard phase contains carbonitrides of at least tungsten, titanium, tantalum, niobium, and vanadium.