JP2003293071A - WC-Co CEMENTED CARBIDE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the durability of a cemented carbide. <P>SOLUTION: The cemented carbide has a composition which contains WC and Co as main components and into which NbC is incorporated and also either or both of TiCN and TiN are added. In this way, high hardness and high toughness can be obtained owing to WC and Co, and oxidation resistance and heat resistance can be improved by NbC and nitrogen derived from TiCN or TiN. By combining these various characteristics in a good balance, durability can be improved. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a WC-Co type cemented carbide having improved durability by combining various characteristics such as hardness, toughness, oxidation resistance and heat resistance in a well-balanced manner.

[0002]

2. Description of the Related Art Conventionally, cemented carbide has been widely used as a material for cutting and cutting tools of metals (iron and stainless steel). Cemented carbide is an iron group metal (Fe, Co,
Ni) as a binder, 4A group of the periodic table, 5A group, 6
Group A metals (Ti, Zr, Hf, V, Nb, Ta, Cr,
Mo, W) is a composite material obtained by sintering carbide particles, and WC (tungsten carbide) -T for cutting tools.
The iC (titanium carbide) -TaC (tantalum carbide) -Co (cobalt) system is currently the mainstream.

[0003]

However, the cemented carbide of the above composition contains several kinds of metal carbides,
Although various properties such as hardness, toughness, oxidation resistance, and heat resistance are obtained with a high degree of balance, tantalum, which is a rare element, is not only very expensive compared to tungsten, etc. However, since it is consumed in large quantities as a material for electronic device parts and it will inevitably become difficult to obtain in the near future, the development of cemented carbide containing no tantalum has been earnestly desired. Further, in order to cope with the recent speeding up and severer cutting conditions, it is required to improve the durability, but it is difficult to realize without using tantalum.

[0004]

In view of the problem that it is difficult to improve durability without depending on tantalum, which is based on the above-mentioned conventional technique, the present invention contains WC and Co as main components and contains NbC. Together with TiCN and / or TiN, by adding WC and C
o combines high hardness and high toughness in a good balance,
The above-mentioned problems are solved by improving oxidation resistance and heat resistance with NbC and a nitrogen content derived from TiCN or TiN.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The WC-Co based cemented carbide according to the present invention contains WC (tungsten carbide), which is a hard material, and Co (cobalt), which is relatively soft and rich in toughness, as main components, and has high oxidation resistance of NbC (niobium carbide). ) Together with TiCN (titanium carbonitride)
Is added to make the composition contain a nitrogen content.

The content of each component in the cemented carbide is WC 5
If less than 0% by weight and Co is more than 20% by weight,
If the hardness is insufficient, the wear resistance is low, and if WC is more than 90% by weight and Co is less than 3% by weight, the impact resistance is low. Therefore, the content of WC is 50 to 90% by weight, It is preferable that the content is in the range of 3 to 20% by weight so that both hardness and toughness can be obtained with good balance.

When the NbC content is less than 5% by weight, the oxidation resistance and heat resistance are low, and when used as a cutting tool, oxidation progresses due to frictional heat with the work piece and oxygen in the air. Durability is significantly reduced, and if it exceeds 15% by weight,
Since the bending strength is lowered and it is easily broken by the pressure applied during cutting, the range of 5 to 15% by weight is preferable.

If TiCN containing a large amount of nitrogen is used, it is decomposed during sintering (during the production of a cemented carbide) described later, and the nitrogen is diffused, so that C (carbon) and N are contained.
It is preferable that the ratio of (nitrogen) is 7/3 by weight.
The addition ratio of N (7/3) is preferably in the range of 5 to 15% by weight for the same reason as in the case of NbC described above. Also, Ti
Part of CN may be replaced with TiN, or TiN may be added without using TiCN at all. The addition rate when TiN is used alone is the same as in the case of TiCN (7/3) above. Therefore, the range of 1 to 5% by weight is preferable. In short, the feature of the present invention is that the composition contains both NbC and nitrogen, and the oxidation resistance and heat resistance are improved by NbC and nitrogen derived from TiCN or TiN. Incidentally, other trace components are not particularly limited,
Other metal carbides such as TaC and TiC, Fe and Ni
A small amount of other iron group elements such as

Next, a method for producing the WC-Co type cemented carbide of the present invention will be described. First, WC powder, Co powder, N
bC powder, TiCN powder, and TiN powder are mixed in a predetermined ratio (content ratio of each component described above, any ratio within the addition ratio), and the mixture is mixed using a mixer such as an attritor and mixed. Disperse each component in the product uniformly. Incidentally, Ti
Only one of the CN powder and the TiN powder may be used. Next, the compound is molded into a desired shape by an appropriate method such as pressure molding, and the molded body is placed in a vacuum atmosphere at 1350 to 1450.
Sinter in the temperature range of ° C. The reason why sintering is performed in a vacuum atmosphere is to obtain a dense sintered body having no pores by sintering while removing the gas from the molded body. In the case of producing a complex shaped article, pre-sintering may be performed at a temperature lower than the main sintering after forming, and the pre-sintered body may be subjected to forming processing such as cutting and then main sintering.

The present invention will be described in more detail based on the following examples. First, WC powder, TiCN powder, Nb
C powder and Co powder were mixed at a ratio shown in Table 1 (test body), and the mixture was molded into a predetermined shape, and then sintered under the above-mentioned conditions to be a test body of a circular saw tip (the present invention). Product) was produced. Then, 90 test pieces were attached around a circular saw having a diameter of 355 mm, and the circular saw was rotated at a rotation speed of 1500 r.
A SUS304 pipe having a thickness of 2 mm and an outer diameter of 50 mm was repeatedly cut and set in a pm cutting machine to perform a durability test. As a comparison target, the same test was performed using two types of conventional chips (conventional product 1 and conventional product 2). The compositions of the test body of the present invention and the conventional products 1 and 2 are shown in Table 1, and the test results of each are shown in Table 2 together with the measured values of hardness.

[0011]

[Table 1]

[0012]

[Table 2]

As shown in Table 2, the conventional product 1 can withstand only 10 cuts, whereas the conventional product 2 and the test body of the present invention can withstand 100 cuts. The friction area of the body was about half that of the conventional product 2, demonstrating its excellence.

[0014]

In summary, according to the present invention, since WC and Co are main components and NbC is contained, and TiCN and / or TiN are added, high hardness and high toughness as well as high oxidation resistance, It has high heat resistance as well as improved durability, making it ideal as a material for metal working tools (tips for circular saws, drills, etc.). Furthermore, since durability is not dependent on rare and expensive tantalum, it is possible to avoid difficulty in obtaining raw materials due to depletion of tantalum, and at the same time reduce the cost of consumable metal processing tools for metal processing. The cost required can be reduced.

The ratio of each component is WC50-90% by weight, C
3-20 wt%, NbC 5-15 wt%, TiCN0
.About.15 wt%, and TiN 0-5 wt%,
The hardness, toughness, oxidation resistance, heat resistance, and other properties that greatly affect the durability of metal working tools can be combined in a high-dimensional manner in a well-balanced manner to dramatically improve the durability of metal working tools. Its practical effect is enormous.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Hiramatsu             11 Shirayama, Toyooka-cho, Gamagori-shi, Aichi 3 Japan Special             Special alloy Co., Ltd. (72) Inventor Kosuke Shimizu             11 Shirayama, Toyooka-cho, Gamagori-shi, Aichi 3 Japan Special             Special alloy Co., Ltd. (72) Inventor Hideaki Matsubara             2-4-1, Rokuno, Atsuta-ku, Nagoya-shi, Aichi               Fine Ceramics Center Foundation             Within

Claims (2)

[Claims] 1. A WC-Co based cemented carbide containing WC and Co as main components, containing NbC, and adding TiCN and / or TiN. 2. The proportion of each component is WC50-90% by weight,
Co3 to 20% by weight, NbC 5 to 15% by weight, TiCN
The WC-Co based cemented carbide according to claim 1, characterized in that the content is in the range of 0 to 15% by weight and TiN in the range of 0 to 5% by weight.