JPS602377B2 - Sintered material for cutting tools with excellent high-temperature properties - Google Patents

Description

[Detailed Description of the Invention] The present invention provides a material that exhibits excellent high-temperature properties and exhibits excellent performance when used as a cutting tool in high-speed cutting and high-feed cutting that particularly require these properties. It is related to.

Generally, when cutting steel, when the cutting speed is increased or the feed rate is increased, the temperature of the cutting tool's cutting edge increases, and the cutting tool reaches the end of its useful life due to plastic deformation caused by the high temperature rather than wear. In many cases, this preference is becoming stronger due to the recent advances in high-speed cutting and high-efficiency cutting.

However, the cemented carbides and cermets currently in practical use whose dispersed phase is mainly composed of W carbide or Ti carbide, while the binder phase is mainly composed of iron group metals, rapidly deteriorate when the cutting edge temperature exceeds 1000 qo. Because of this, not only these cemented carbide and cermet, but also surface-coated cemented carbide and surface-coated cermet, which have a hard coating layer formed on their surface, must be used at a cutting edge temperature of 1000°C. It is limited to slightly more than that. On the other hand, ceramics containing AI oxide as a main component exhibit high hardness and excellent oxidation resistance at high temperatures, and are therefore used in practical applications as high-speed cutting tools.However, even with this ceramic, the cutting edge lacks high-temperature stability. However, due to insufficient reliability, the current situation is that low feed rates are used during high-speed cutting. In addition, in recent years, cast alloys having a structure in which carbides of W and Ti are dispersed in layers in a matrix of high-melting point metals such as W or Mo have been proposed as cutting tool materials for high-speed cutting and high-feed cutting. (See, for example, US Pat. No. 3,690,962),
However, this cast alloy has a significantly high melting point of 270 mm, is difficult to shape, and has insufficient oxidation resistance and impact resistance, so it has not been widely put into practical use. However, it did not reach the point where it was possible to do so.

Therefore, from the above-mentioned viewpoint, the present inventors have developed a technology that enables high-speed cutting and high-feed cutting, and has excellent wear resistance, plastic deformation resistance, oxidation resistance, and impact resistance, that is, excellent high-temperature properties. As a result of research to obtain materials for cutting tools having
One or two of f: 5-30%, Nb and T
One or two of a: 5-30%, C: 20-4
0%, Si: 1 to 10%, and the remainder consists of W and unavoidable impurities (however, W: 20 to 60%) (at %), and the broiling temperature in the sintering process is is heated to a high temperature to completely solidify the constituent components, and when the temperature is lowered to a lower temperature, the dispersed phase consists of a compound phase containing Ti and C as main components, one or two of Zr and Hf, and C. It consists of a fine hard phase consisting of a compound phase whose main components are W and a compound phase whose main components are Si and C, while the binder phase has a structure consisting of a high melting point alloy phase whose main components are W and Si. In the resultant condensed material, the inclusion of Si improves the thermal resistance and significantly reduces material defects such as cavities and small holes, which improves the impact resistance of the material. The high melting point alloy phase mainly composed of W and Si (W poppy, compound) as a binder phase provides excellent plastic deformation resistance, oxidation resistance, and wear resistance, and the fine hardness Coupled with the excellent wear resistance of the dispersed phase, they found that when used as a cutting tool for high-speed cutting or high-feed cutting, it exhibits extremely excellent cutting performance.

This invention was made based on the above knowledge, and the reason why the component composition range was limited as described above will be explained below.

{a'Ti Ti forms a compound phase mainly composed of Ti and C, giving the material high hardness and thereby improving wear resistance, but if its content is less than 10 at% During the cooling process from the solid solution state in the sintering process, the desired amount of fine compound phase mainly composed of Ti and C could not be precipitated, resulting in poor wear resistance; If the content exceeds 10%, the amount of dispersed phase becomes too large relative to the binder phase, resulting in deterioration of impact resistance. Therefore, the content was set at 10 to 35 at%.

[b} Zr and Hf Similar to Ti, these components also have the effect of precipitating and forming a compound phase mainly composed of one or two of Zr and Hf and C to improve wear resistance. The amount is 5 atomic%
If the content is less than 30 atomic %, the desired high hardness and high wear resistance cannot be achieved like with Ti, while if the content exceeds 30 atomic %, the dispersed phase becomes too large and the impact resistance deteriorates. The content is 5 to 30%.
Defined as atomic percent.

'c-Nb and Ta These components have the effect of improving oxidation resistance by diffusing into the compound phase whose main components are Ti, Zr, and C, respectively, but their content is 5 at%. If the content is less than 30 atomic %, the desired effect cannot be obtained, whereas if the content exceeds 30 atomic %, the wear resistance decreases. Therefore, the content was set at 5 to 30 atomic %.

(As mentioned above, the C component combines with Ti, Zr, m, Nb, Ta, and Si, and in some cases W, to form a dispersed phase consisting of a fine hard phase, which improves the wear resistance of the material.) However, if the content is less than 20 at%, the amount of dispersed phase is relatively too small to ensure the desired wear resistance, while if the content exceeds 40 at% , the amount of dispersed phase relative to the binder phase becomes too large and the impact resistance of the material deteriorates.
It was set at 40 atom%.

{c-Si The Si component imparts excellent impact resistance to the material by improving sinterability as described above, and also reacts with W and free C to form W poppy, compound, and Si carbide, respectively. When the content is less than 1 atomic %, the desired effect cannot be obtained; on the other hand, when the content exceeds 10 atomic %, W poppy has the effect of significantly improving the wear resistance of the material. , carbide and Si carbide become too large, resulting in a decrease in impact resistance, so their content was determined to be 1 to 10 at %.

A part of the 'f' WW component mainly combines with Ti and C to form a dispersed phase, and the remaining main part forms a high melting point alloy phase as a binder phase with Si, thereby improving the plastic deformation resistance of the material. , has the effect of improving oxidation resistance and impact resistance, but if its content is less than 20 at %, the binder phase will be relatively small and the proportion to Si will also be low, so that the desired effect will not be achieved. On the other hand, if the content exceeds 60 atomic %, the wear resistance and oxidation resistance will deteriorate, so the content was set at 20 to 60 atomic %.

The fried stripe material of the present invention contains one or more of oxygen, nitrogen, Fe, Co, Ni, Cr, Mo, AI, etc. as inevitable impurities, but the total content is 5 atomic % or less. If present, the properties of this coagulated material will not be impaired in any way.

Next, the advanced material of the present invention will be explained in detail with reference to Examples.

Example 1 As raw material powders, titanium carbide powder with an average particle size of 1.0 mm, zirconium carbide powder with an average particle size of 1.5 mm, and 1.5 mm particle size were used.
5. Prepare hafnium carbide powder of 1.0 μm, tantalum carbide powder of 1.0 rm, W powder of 0.8 rm, and Si powder of 1.5 rm, and these raw material powders are shown in Table 1. The mixture was wet-mixed in a ball mill for 7 hours, dried, and then press-molded at a pressure of 1.5k9' to form a green compact.Then, this powder was heated at 10-1℃.
After freezing at a temperature of 2100°C for 1 hour in a vacuum of RR, cooling the temperature range from the competitive fringe temperature to 1000qo at a cooling rate of 400°C/hr,
Competitive materials 1 to 5 of the present invention and Hisame baked striped striped materials 1 to 6 having substantially the same final component composition as the blended composition were produced, respectively.

It should be noted that Hisame Sintered Materials 1 to 6 each have a composition in which one of the constituent components (indicated by * in Table 1) is outside the scope of the present invention. Next, the resulting composite materials 1 to 5 of the present invention and comparative cadaver materials 1 to 5 were prepared.
6, a cutting tip with the shape of SNP432 was prepared, and the workpiece material: JIS/SNCM-8 (hardness: HB250
), Cutting speed: 250 skin'min, Feed: 0.3 side'r
Continuous cutting test under the conditions of ev, depth of cut: 2 ribs, cutting time: 10 minutes, and workpiece density: JIS/SNCM-8 (hardness: HB280), cutting speed: 140 machine'min, feed 0
．． An intermittent cutting test was conducted under the conditions of 3 skins, depth of cut: 2 fences, and cutting time: 3 minutes.In the above continuous cutting test, the flank wear depth and crater wear depth on the chip cutting edge were measured. In the cutting test, the number of missing cutting edges out of the number of cutting edges 1q was measured.

These measurement results are also shown in Table 1. In addition, the first
For comparison purposes, the table shows a commercially available ceramic cutting tip whose main component is aluminum oxide (hereinafter referred to as conventional cutting tip 1), and a tungsten carbide-based cemented carbide substrate with titanium carbide and aluminum oxide on the surface. The results of a cutting test under the same conditions for a surface-coated cemented carbide cutting tip (hereinafter referred to as conventional cutting tip 2), which is coated with two hard layers, are also shown. Table 1 As shown in Table 1, the cutting inserts manufactured using the inventive sintering materials 1 to 5 were evaluated in continuous and interrupted cutting tests as compared to the cutting chips manufactured using the comparative sintering materials 1 to 6. It is clear that the cutting performance is much better than that of chips 1 and 2.

Example 2 In addition to the same raw material powder used in Example 1, niobium carbide powder having an average particle size of 1.2 mm was prepared as raw material powder, and these raw material powders were prepared as shown in Table 2. The present invention Aya materials 6 to 9 and the comparative Akio Aya materials 7 to 1 were prepared under the same conditions as in Example 1 except that they were added to the blending composition.
2 were produced respectively.

Next, cutting tips each having a shape of SNP432 were prepared from the obtained Akatsuki Materials 6 to 9 of the present invention and Comparative Materials 7 to 12, respectively, and the work material was JIS/SN.
CM-8 (hardness: HB250), cutting speed: 100/
Continuous cutting test under the conditions of min, feed: 0.7 skin/rev, depth of cut: 8 winds, cutting time: 1 minute, work material: SN
CM-8 (hardness: HB280), cutting speed: 100/
Example 1 An intermittent cutting test was conducted under the conditions of min, feed: 0.4 Yanagi/rev, depth of cut: 3 ribs, and cutting time: 3 minutes.
In the continuous cutting test, the flank wear depth and crater wear depth were measured on the same machine, and in the interrupted cutting test, the number of chips in one hard cutting edge was measured.

The measurement results are also shown in Table 2. Table 2 Also, for comparison purposes, Table 2 shows surface-coated cemented carbide cutting tips (all of which are made of a commercially available tungsten carbide-based cemented carbide substrate coated with a hard layer of titanium carbide). Also shown are cutting test results under the same conditions for a P30 tungsten carbide-based super metallurgical cutting tip (hereinafter referred to as conventional cutting tip 4).

Claims (1)

[Claims] 1 Ti: 10-35%, one or two of Zr and Hf: 5-30%, one or two of Nb and Ta: 5-30%, C: 20-40%, Si :1
~10%, and the rest is W and unavoidable impurities (however, W
:20 to 60% content) (at least atomic %), and the dispersed phase is a compound phase containing Ti and C as main components, one or two of Zr and Hf, and C. It consists of a fine hard phase consisting of a compound phase whose main components are W and Si and a compound phase whose main components are W and Si.
A sintered material for cutting tools with excellent high-temperature properties, characterized by having a structure consisting of a high melting point alloy phase whose main component is