JPS59153862A - Sintered hard tungsten carbide alloy member for cutting tool and production thereof - Google Patents

Abstract

PURPOSE:To provide a titled sintered hard alloy member having the resistance to wear, plastic deformation and impact by providing a prescribed average layer thickness of an O2-contg. surface layer to a sintered hard WC alloy member contg. ferrous metals as a component for forming a bond phase and carbide, nitride, etc. of 4a and 5a group metals as a component for forming a hard phase. CONSTITUTION:A sintered hard WC alloy member contg. respectively 5-30% >=1 kind among ferrous metals as a component for forming a bond phase, and 5-50%>=1 kind among carbide and nitride of 4a and 5a group metals of periodic table as a component for forming a hard phase is prepd. The member is subjected to a heating treatment in an O2-contg. atmosphere under a temp. condition of 1,200-1,300 deg.C to form an oxygen-contg. surface reaction layer having 10-400mum average layer thickness. The contents of the ferrous metal in the central part of the member and the carbide and nitride thereof are regulated respectively at 0.1-0.9 the ferrous metal and 1.2-2.5 the carbide and nitride in the ratio thereof in the member body.

Description

[Detailed Description of the Invention] This invention has excellent wear resistance, plastic deformation resistance, and impact resistance, and is particularly suitable for use as a cutting tool in milling cutting, interrupted cutting, etc. where these characteristics are required. Tungsten carbide (hereinafter referred to as W) exhibits excellent cutting performance when
The present invention relates to a cemented carbide member (indicated by C) and a manufacturing method thereof.

Conventionally, for example, We-C! o Cemented carbide parts can be used as cutting tools for cast iron, and we - (w, T, t, Ta) O
-CO is used as a cutting tool for cemented carbide steel.

In these conventional WC-based super-superalloy parts, the Co content and (TjC+TaC) content are changed as appropriate depending on the cutting application, but as the Co content increases, the impact resistance of the part decreases. However, on the other hand, the wear resistance and plastic deformation resistance deteriorated (TiC+
For cutting tools that have all of wear resistance, plastic deformation resistance, and impact resistance. W.C.
At present, C cemented carbide members have not yet been developed.

On the other hand, in order to take advantage of the impact resistance of the conventional WCC cemented carbide member mentioned above and add ML abrasion resistance to it,
4a and δ of the periodic table on the surface of the WCC cemented carbide member.
a, and carbides, nitrides, oxides, sulfides, and borides of Group 6a metals, and solid solutions of two or more of these;
Additionally, Ag203 and /VN.

and a surface-coated WCC formed by forming a coating layer consisting of a single layer of one type or a multilayer of two or more types from the group consisting of solid solutions of the two components using a chemical vapor deposition method, a physical vapor deposition method, etc.
It has been proposed for use in cemented carbide materials and is widely used in the turning field. However, in forming the coating layer, typically T], C14, CH4, H2, N2, etc. are used as reaction gases, which not only makes the apparatus itself complicated but also increases the cost. Corrosion of equipment structural members due to Ct gas generated by decomposition of 54,
and safety management such as prevention of AT gas leaks - there are many problems.

In the case of the surface-coated WCC cemented carbide member described in -4-2, when the coating layer is formed by chemical vapor deposition, it is impossible to avoid the formation of a decarburized layer on the surface of the substrate directly under the coating layer. When a decarburized layer is formed in this way, the toughness of the material itself decreases, so if this material is used for milling or interrupted cutting that involves high impact, it will not necessarily show satisfactory cutting performance. It is something.

Therefore, from the above-mentioned viewpoint, the present inventors have attempted to achieve excellent wear resistance, plastic deformation resistance, and impact resistance without using coating layer forming methods such as chemical vapor deposition or physical vapor deposition. As a result of research to obtain a WC cemented carbide member for cutting tools that has the following properties, we found that, in terms of weight, the binder phase forming component and one or two of the iron group metals: 5- 30 candy, one or more carbides and nitrides of metals from groups 4a and 5a of the periodic table as hard phase forming components (
These are hereinafter collectively referred to as metal carbon/nitrides): 5~
Section 50, a WCC cemented carbide member having a composition in which the remainder similarly consists of WC as a hard phase forming component and unavoidable impurities, heated and maintained at a predetermined temperature within the range of 1200 to 1350°C in an oxygen-containing atmosphere. When heat treatment is performed under these conditions, the constituent components of the member react with oxygen in the atmosphere on the surface of the member, forming a stable oxide, and during this time, the space between the inside of the main body and the surface Because diffusion of the constituent components occurs, the content of metal carbon and nitride is relatively high compared to the inside of the member body, while the content of iron group metals is low, including oxygen. As a result, a surface reaction layer with a continuous concentration gradient is formed on the surface of each component, and this surface reaction layer is
It has an average layer thickness of μn7, and the content of iron group metals and metal carbon/nitrides in the central part is 1 or more harmful to that inside the member body, iron group metals: 0.1 to 0.9゜Metal carbon/nitride: 12~25゜'fc 7Pa shall be added, the resulting surface reaction layer will have excellent wear resistance and plastic deformation resistance, therefore WCC cemented carbide They found that the material has excellent wear resistance, plastic deformation resistance, and impact resistance.

This invention was made based on the above knowledge,
When carrying out the method of this invention, it is preferable to use a CO2 atmosphere as the oxygen-containing atmosphere, because CO2 easily changes to Co at high temperatures, and although the oxygen partial pressure is extremely low, the initial oxidation of the reaction is This is because the decarburization caused by CO and the carburization caused by CO in the latter stage of the reaction cancel each other out, resulting in the advantage that the carbon content of the member itself hardly changes.

Naive, regarding the oxygen content in the surface reaction layer of this invention, it is impossible to measure the oxygen content of only the surface reaction layer, but if you measure the oxygen content of the entire member, it will be 02 to 2.
．． Since the oxygen content of the member with the blade surface reaction layer removed is 0.03 to 0.1%, the oxygen content in the surface reaction layer must be at least 02% or higher. is estimated.

Next, in this invention, the reason why the component composition of the we-based cemented carbide, the average layer thickness and component content of the surface reaction layer, and the heat treatment temperature are limited to the following will be explained.

A. WCC cemented carbide component composition (a) Iron group metal These components have the effect of improving the impact resistance of the component, but if their content is less than 5%, the desired impact resistance may not be achieved. On the other hand, if the content exceeds 30%, the wear resistance will decrease, so the content was set at 5 to 30%.

(b) Metallic carbon/nitride These components have the effect of improving the wear resistance and plastic deformation resistance of parts, but if their content is less than 5%, the desired effects may not be achieved. Not only is it not possible to obtain this, but a surface reaction layer with poor wear resistance and plastic deformation resistance cannot be formed, and on the other hand, if the content exceeds 50%, the impact resistance of the member will be significantly reduced. Therefore, the content was determined to be between 5 and 50.

B1 Surface reaction layer (a) Average layer thickness If the average layer thickness is less than 10 μm, the desired excellent wear resistance and plastic deformation resistance cannot be ensured, while if the average layer thickness exceeds 400 μm, the surface As fine chipping begins to occur in the reaction layer itself, and this may develop into cracks, the average layer thickness is reduced to 10 to 4
00 μm.

(b) Component content ratio The content of iron group metals and metal carbon/nitrides in the surface reaction layer can be changed depending on the heat treatment conditions, but the content of iron group metals in the central part of the surface reaction layer is If the ratio of iron group metals exceeds 0.9i, the wear resistance and plastic deformation resistance of the surface reaction layer will deteriorate, while if the ratio is less than 0.1, the surface reaction layer itself will become brittle. The content ratio of iron group metal in the surface reaction layer is from 50.1 to 0.
It was set as 9.

In addition, if the content of metal carbon/nitride in the central part of the surface reaction layer is less than 1.2 in proportion to that of carbon/nitride inside the member body, desired excellent wear resistance and plastic deformation resistance can be achieved. However, the same ratio is 2.5
If it exceeds this, the surface reaction layer becomes extremely brittle and cracks are likely to occur, so the content ratio of metal carbon/nitride in the surface reaction layer was determined to be 1.2 to 2.5.

C0 heat treatment temperature If the temperature is less than 1200°C, the formation of a surface reaction layer will hardly take place, while if the temperature exceeds 1350°C, roughness will occur on the surface of the member and it will be difficult to ensure the specified dimensional accuracy. Because it becomes difficult, the temperature should be set at 1200~1
The temperature was set at 350°C.

Next, the present invention will be specifically explained with reference to Examples.

As the raw material powder of the example, average particle size: 2.2 μynfr w
C powder, same 1.0μ? T'i0 powder of n, 1.3 p
ZrO powder of 1.2 μm, HfC powder of 1.2 μm
pm VC powder, same 1.0 pm N1) O powder, same 1.0 pm
．． 1 pm TaO powder, 1.2/1 m TiN powder, 1.8 μm ZrN powder, 2.0 μm HfN powder, 2.0 μm VN powder, 1. '8μm NbN
Powder 2 1.7 pm TaN powder, 1.2 pm C
o powder.

N1 powder with a diameter of 183 μm and Fe powder with a diameter of 1.2 μm are prepared, these raw material powders are appropriately blended, mixed under normal conditions, and then molded into a green compact. Each was held at the temperature shown in Table 1 for 1 hour in a vacuum of 10-2 torr to form a sintered body having the component composition shown in Table 1, and then sintered with J Engineering S Standard 5.
After polishing into a shape conforming to NP432, heat treatment was performed under the conditions shown in Table 1 to obtain cemented carbide chips 1 to 25 of the present invention and comparative cemented carbide chips 1 to 4, each having a surface reaction layer. were manufactured respectively. In addition,
Comparative cemented carbide chips 1 to 4 were all manufactured under conditions in which either the composition or the heat treatment temperature was outside the scope of the present invention (marked with * in Table 1).

Next, the obtained cemented carbide chip of the present invention]~2
5 and comparative cemented carbide chips 1 to 4, the average layer thickness of the surface reaction layer was measured, and the content of iron group metals and metal carbon/nitrides in the central part of the surface reaction layer and inside the chip body was measured. , the content ratio was calculated. These results are shown in Table 1.

In addition to the above-mentioned cemented carbide chips 1 to 25 of the present invention and comparison cemented carbide chips 1 to 4, prepared for the purpose of comparison,
Conventional cemented carbide tips 1 to 5f shown in Table 1, respectively
: Used, (a) Work material: SNOM-8 (hardness: HB22
0), Cutting speed: 200 nI/min, Feed: 0.36 mm/rev, Depth of cut: 1.5+mn, Cutting time: 10ml7+, Continuous cutting test under the following conditions (hereinafter referred to as cutting condition A), (b) Workpiece Material: SNCM-8 (hardness: HB280)
, cutting speed 140 m 1 mm, feed: 0.3 mm/rev, depth of cut 2I+ll11, cutting time 3 min, Intermittent cutting test under the following conditions (hereinafter referred to as cutting condition B), (C) Work material: SNC! M-8 (hardness HB 240
), cutting speed 130 m/mUI, feed rate 5: 0.45 cylinder/rev, depth of cut 2 intervals, cutting time 1 (llIn), continuous cutting trial under the following conditions (hereinafter referred to as cutting condition C): 10
0 darkness), lino cutting speed '475m/I'fHn, feed 0.3
mm/rev, depth of cut 4 mm, cutting time H20nun.

Tool diameter: 160mm (single edge), and the center of the tool was aligned on the longitudinal center line of the workpiece material, and a face-flask cutting test was carried out under dry conditions (hereinafter referred to as cutting conditions). (θ) Work material SNCM-8 (hardness HB260), cutting speed 150 m 7 mIn, feed 0.375 mm/r e v4, depth of cut 2
mm, Cutting time: 10 min, Continuous cutting test under the conditions (hereinafter referred to as cutting conditions E), +f) Workpiece profit S N C! ls -8 (hardness
HB280), cutting speed: 100 m 1 mIn, feed,! 7: An interrupted cutting test was conducted under the following conditions (hereinafter referred to as cutting condition F): 0.375 cylinder/rev, depth of cut: 2 mm, cutting time: 3 min. In the continuous cutting test described in -, the flank surface of the chip cutting edge was The wear width and rake face wear depth were measured, and in the above-mentioned interrupted cutting test, the number of missing cutting edges among the 10 tested cutting edges was checked.Furthermore, in the above-mentioned face milling cutting test, the flank surface of the cutting edge was checked. The number of cracks on the flank of the cutting edge in this state is
The total crack length and average crack length were measured.

The results of these measurements are shown in Table 2.

From the results shown in Table 2, the cemented carbide chips 1 to 1 of the present invention
No. 25 has excellent wear resistance, plastic deformation resistance, and impact resistance, so it shows extremely excellent cutting performance in all cutting tests, whereas Comparative Cemented Carbide No. 1 It is clear that the conventional cemented carbide tips 1 to 4 and conventional cemented carbide tips 1 to 5 do not necessarily exhibit satisfactory cutting performance because they are inferior in at least one of the above characteristics.

As described above, according to the present invention, a WC that does not require large-scale equipment, does not easily cause major problems in terms of safety management, and has excellent wear resistance, plastic deformation resistance, and impact resistance. The base super superalloy part can be manufactured at low cost, and when used as a cutting tool, especially for 7-rice cutting or interrupted cutting, it has industrially useful effects such as extremely excellent cutting performance. It is possible.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo and 1 other person

Claims (2)

[Claims] (1) A tungsten carbide-based cemented carbide member having an oxygen-containing surface reaction layer with an average layer thickness of 10 to 400 μm, the main body of the cemented carbide member comprising one of the iron group metals as a binder phase forming component. Seed or 2
Species or more: 5 to 30%, one or more carbides and nitrides of group 4a and 5a metals of the periodic table as hard phase forming components (
These are hereinafter collectively referred to as metal carbon/nitrides): 5~
50%, with the remainder consisting of tungsten carbide as a hard phase forming component and inevitable impurities (weight%)
and the content of iron group metal and metal carbon/nitride in the two central portions of the surface reaction layer is respectively iron group metal: 0.1 in proportion to that of the main body of the cemented carbide member. ~0
．． A tungsten carbide-based cemented carbide part for a cutting tool, characterized in that it satisfies the angle of 9° metal carbon/nitride 12 to 25°. (2) One or more iron group metals as a binder phase-forming component: 5 to 30 carbides and nitrides of metals from groups 4a and 5a of the periodic table as hard phase-forming components. One or more types of (
These are hereinafter collectively referred to as metal carbon/nitrides): 5~
A composition containing 50% of
A tungsten carbide-based cemented carbide member with
, and the content of iron group metals and metal carbonitrides in the central part is the ratio to that of the main body on the side of the cemented carbide part, respectively. A method for manufacturing a tungsten carbide-based cemented carbide member for a cutting tool, which is characterized by forming an oxygen-containing surface reaction layer satisfying a carbon/nitride angle of 12 to 2.5°.