JPS62107006A - Sintered hard alloy member for plastic working and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a sintered hard alloy member for plastic working having high toughness and causing little deformation by sintering an alloy consisting of a WC-base hard phase and a binding phase of an iron group metal and by producing a specified percentage of permanent set in the sintered alloy as compared with the state after the sintering. CONSTITUTION:An alloy consisting of a WC-base hard phase and a binding phase of an iron group metal is sintered. Compressive stress above the yield stress of the sintered alloy is produced in the alloy, and after the stress is relieved, >=0.3% permanent set is produced in the sintered alloy as compared with the state after the sintering. The upper limit of the permanent set depends on the amount of the binding phase but is usually about half of the fracture strain.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a cemented carbide for plastic use, and more specifically to a cemented carbide for use in dies, punches, etc., which has high M properties and less deformation. (and relates to a cemented carbide for plastic working with good dimensional accuracy and a manufacturing method thereof.

[Prior art]

Traditionally, tool steels such as die steel and high-speed steel have been mainly used for plastic working tools such as dies and bunches, but in recent years, with advances in cemented carbide and plastic working technology, many wCC cemented carbide alloys have been used. It has come to be used conveniently.

The main reason for this is that cemented carbide has higher hardness and superior wear resistance than the tool steels mentioned above. It has high compressive strength and can perform plastic working under high loads. High Young's modulus and good ability to maintain dimensional accuracy. It has many advantages as a tool material for plastic working.

[Problem that the invention seeks to solve]

However, in precise plastic working that requires a more precise shape, not only tools made of tool steel but also tools made of cemented carbide often deform and cannot maintain sufficient accuracy. In this case, a tool that has been corrected by estimating and calculating the amount of deformation of the tool itself is used; There are problems such as not being able to obtain products.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and its primary purpose is to provide a precision plastic working tool that can withstand long-term use and maintain sufficient accuracy - a cemented carbide member suitable for plastic working. The first object of the present invention is to provide a method for manufacturing a cemented carbide member for plastic processing.

[Means for solving problems]

The present invention solves the above-mentioned problems by using the configuration described below.

That is, in a sintered alloy mainly composed of WC as a hard phase and an iron group metal as a binder phase, a cemented carbide member for plastic working that has a permanent strain of α3% or more compared to the state after sintering of the alloy is used. The first gist is mainly WC as a hard phase,
After sintering an alloy having an iron group metal as a binder phase, a compressive stress higher than the yield stress of the alloy is applied, and after the compressive stress is unloaded, a permanent strain of 0.3% or more is created in the alloy. The second gist is a method for producing a cemented carbide member for plastic working.

[Action of the invention]

The above-mentioned cemented carbide members for plastic working have a higher Young's modulus and a significantly higher yield stress than conventional cemented carbides. As a result, the amount of distortion during actual use up to a certain load is significantly reduced compared to the cemented carbide mentioned above, and when used as a plastic working tool, accuracy can be maintained extremely well. As a result, changes in accuracy become extremely small even after multiple uses.

In addition, Ff! mainly consists of we! Even in small amounts, iron group metals, which bind the qualitative phases, promote plastic deformation of the alloy.
The amount of deformation is extremely small.

In addition, in order to produce a permanent strain of 0.3% or more in an alloy with a small amount of binder phase, it is necessary to apply a load close to the limit value of the compressive strength of the alloy, which is not preferable because it leads to the alloy's failure. A binder phase amount of 8 wt% or more is appropriate and effective. The amount of deformation of the alloy increases as the amount of the binder phase increases, and in order to provide effective permanent strain, the larger the amount of the binder phase, the more preferable it is, but from a practical standpoint, it is preferably within the range of 15 to 23 wt%.

If the amount of permanent strain of the alloy is 0.3% or less, there is no significant advantage in maintaining tool accuracy. Regarding the upper limit value, since the amount of strain changes from the point of bonding phase to breakage, it is appropriate to set the amount of strain up to about half of the strain at break, which cannot be numerically expressed as the amount of strain.

The metal used as the binder phase may be cobalt or ~2.2 Likel. Co-Jtl-Or yarn may also be used, but an alloy with Ni-like p as a binder phase is more effective than cobalt because it is more easily plastically deformed and causes significant permanent strain.

〔Example〕

Examples will be described below.

As shown in Table 2t, We-15 to 23% co and We-cri C
2-Co-Ni alloy was made.

Note that the comparative alloy L Z 3.11 is an alloy that is not subjected to any post-sintering treatment after sintering, and the alloy according to the present invention was obtained by applying compressive stress of the values shown in Table 1. The amount of permanent strain generated inside the alloy according to the present invention is shown in Table 2.

Table 1 In the above table, for example, to explain the We-2o<co gold alloy, comparative alloy 2 which is not treated and alloy 5 of the present invention. Although there is almost no difference in characteristic values such as compressive strength and impact value, it can be seen that the alloy of the present invention has a significantly higher value in terms of Young's modulus.

Also, when a load of 250 Klf/- is applied, the comparative alloy 2 has an attempt of 1.55%, whereas the invention alloy 3
．． 11 is reduced by more than half to 0.65% and α55%, respectively. Comparing Inventive Alloy Co. and Comparative Alloy I, the Inventive Alloy has low compressive strength but high impact value, and I7
The amount of strain up to 25 [I Kqf, - is smaller than that of comparative alloy l. In other words, the untreated We-15%Co alloy has a low impact value and cannot withstand use, and in order to increase this lft impact resistance (even if the amount of CO is increased and a 20%Co alloy is made, the mold accuracy will be improved during use). Although it was difficult to maintain
The alloy of the present invention does not have the above-mentioned problems. As shown in the table above, by applying permanent strain to the alloy according to the present invention, the Young's modulus can be greatly increased without deteriorating the mechanical properties, and the amount of strain can be reduced up to a certain load.

〔Effect of the invention〕

/- was given. (Test conditions) In the case of untreated We-15%Co alloy (we particle size of about 2μ), the punches broke at L000 to 2,000 pieces. (
Test results) After sintering WC-16%Co (WC particle size approximately 2 μ), 3 u
The alloy of the present invention, which had a permanent set amount of about 0.6% when pressed at OKg and A-, could be tested up to 10,000 to 15,000 pieces, and the dimensional accuracy of the punched products was also good. (Test results) Next, each of the following samples was formed into an irregularly shaped punch, and the irregularly shaped cup made of 3150 material was forward extruded at a punch surface pressure of 220 K.
This was done by giving ff/-.

Untreated We-15-18%C.

About 2,000 pieces of the alloy (WC grain size about 2μ) broke.

In addition, the We-22%Co alloy (grain size 5μ) had no breakage, but the punch! l! ! The dimensions of the processed product become thicker due to deformation than the specified value @/I0°~I/14
It became bigger by 1g1. Therefore, the punch was re-ground and used again, but the dimensional accuracy was lost after about 1000 pieces.

After sintering WC-22%Co, 2 IIOKGIf/m-
A profiled punch formed from an alloy according to the invention that was pressurized at a blood pressure of 1.5% to a permanent set of about 1.5% was
o, o o o~2 Q O, On 0 pieces could be processed, the life of the punch was greatly extended, and the accuracy was also good.

Claims (2)

[Claims] (1) A sintered alloy mainly composed of WC as a hard phase and an iron group metal as a binder phase, characterized by having a permanent strain of 0.3% or more compared to the state of the alloy after sintering. Cemented carbide parts for plastic working. (2) After sintering an alloy mainly consisting of WC as a hard phase and an iron group metal as a binder phase, a compressive stress higher than the yield stress of the alloy is applied, and after unloading, a permanent strain of 0.3% or more is achieved. 1. A method for producing a cemented carbide member for plastic working, characterized by producing the following.