JPS5952950B2 - Tungsten carbide-based cemented carbide with excellent high-temperature properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes tungsten carbide, which has excellent oxidation resistance, spalling resistance, and heat cracking resistance, especially at high temperatures.
This relates to super hard carbide (hereinafter referred to as WC).

Generally, the hard phase is WC or WC and TiC.

Sintered alloys, which are composed of metal carbides such as TaC and NbC, with a binder phase mainly composed of CO, are usually called cemented carbide, and because they have extremely high strength and hardness, they are used for cutting tools and durability. Widely used for wear tools.

However, although the conventional WC-Co-based cemented carbide has high strength and hardness as described above, it has insufficient oxidation resistance, spalling resistance, and heat cracking resistance at high temperatures. Currently, the field of use is limited, and therefore, depending on the application, it does not exhibit satisfactory performance.

Therefore, from the above-mentioned viewpoint, the present inventors have developed a method for imparting excellent high-temperature properties, such as oxidation resistance, spalling resistance, and heat cracking resistance, to the conventional WC-Co-based cemented carbide. As a result of research, we found that (a) When Ni is included as a bonding phase forming component,
Although some deterioration is seen in heat cracking resistance, plastic deformation resistance, and toughness, oxidation resistance and spalling resistance are further improved.

(b) Shikashi, also as a bonding phase forming component, and C
Inclusion of r can prevent deterioration of heat cracking resistance, plastic deformation resistance, and toughness caused by Ni inclusion.

(C) When one or more of the nitrides of transition metals in groups 4a and 5a of the periodic table (hereinafter collectively referred to as metal nitrides) is included as a hard phase forming component, acid resistance is improved. In addition to corrosion resistance and spalling resistance,
Further improvements in heat cracking resistance, plastic deformation resistance, and toughness.

(d) In addition, as hard phase forming components, one or more of the carbides of transition metals in Groups 4a and 5a of the periodic table and molybdenum carbide (hereinafter referred to as MO3C) (hereinafter collectively referred to as MO3C). Including metal carbides) not only suppresses the growth of WC grains, but also further improves oxidation resistance, plastic deformation resistance, and wear resistance.

The findings shown in sections (a) to (d) above have been obtained.

Therefore, this invention was made based on the above knowledge, and contains 2 to 20% of Cr, with the rest being Ni and C.
o (However, Ni/Co weight ratio = 5/95 to 9515
), a binder phase with a composition consisting of 3 to 30%, metal nitrides: 1 to 30%, further containing 0.5 to 45% of metal carbides as necessary, and the remainder being WC. A hard phase with a composition consisting of unavoidable impurities:
It is characterized by a WC-based super-superalloyed polymer having excellent high-temperature properties.

Next, the reason for limiting the numerical values as described above in the WC-based super-supercombination of the present invention will be explained.

A Binding phase (a) Cr Cr component has the effect of solid solution in CO and Ni components to strengthen the binder phase as a solid solution, thereby preventing deterioration of heat cracking resistance, plastic deformation resistance, and toughness due to Ni content. However, if the content is less than 2%, the desired effect cannot be obtained, while if the content exceeds 20%, toughness deterioration will occur. The ratio to the binder phase was determined to be 2 to 20%.

(b) Ni The Ni component has the effect of improving the oxidation resistance and spalling resistance of the binder phase, but its content in proportion to CO is less than 5%, that is, the Ni/Co ratio is less than 5/95. However, the desired effect of improving the above action cannot be obtained, and on the other hand, when Ni is contained in a proportion exceeding 95% relative to CO, that is, Ni
When the Ni/Co ratio exceeds 9515, the decrease in heat cracking resistance and plastic deformation resistance particularly at high temperatures becomes remarkable.
The o ratio was determined to be 5/95 to 9515.

(C) Ratio of binder phase When the ratio of binder phase is less than 3%, the ratio of hard phase becomes relatively too high, and the amount of liquid phase during sintering becomes insufficient, leaving voids in the alloy. On the other hand, if the content exceeds 30%, the proportion of the hard phase becomes relatively too small, resulting in a significant decrease in hardness. It was set at 30%.

B Hard phase (a) Metal nitride These components, in coexistence with Cr, have high-temperature properties, namely oxidation resistance, spalling resistance, heat cracking resistance, plastic deformation resistance, and toughness. It has a uniform effect to further improve the effect, but if the content is less than 1%, the desired effect cannot be obtained, while if the content exceeds 30%, the sinterability decreases and voids are formed in the alloy. Since this results in residual content, the content is set at 1 to 30% relative to the hard phase.

(b) Metal carbide These components have the uniform effect of suppressing the grain growth of WC and further improving the oxidation resistance, plastic deformation resistance, and wear resistance of the alloy as described above. It is included as necessary when the properties of the above are particularly required, but if the content is less than 0.5%, the desired effect of improving the above function cannot be obtained, whereas if the content exceeds 45%, Since the toughness decreases, its content is determined to be 0.5 to 45% relative to the hard phase.

Incidentally, the WCC cemented carbide of the present invention can be manufactured by a normal powder casting method, but in this case, the raw material powder for forming the hard phase may be a single metal nitride powder, a single metal carbide powder, or a single metal carbide powder. More than one species of nitride and/or
Alternatively, it may be used in the form of a carbide solid solution powder, and as a raw material powder for forming a binder phase, especially for Cr, metal Cr powder, chromium carbide (Cr3C2) powder, or chromium nitride (CrN) powder is used. can do.

Next, the present invention will be specifically explained using examples of WCC cemented carbide.

All of the raw material powders used in the examples were commercially available with an average particle size of 1.5 μm.
r) WC powder, 1.6 μm TiN powder, 1.4 μm
m ZrN powder, 1.3 μm c7) HfN powder, 1.7 μm vN powder, 1.5 μm NbN powder, 1.4 μm TaN powder, 1.5 μm TiC powder, 1.3 μm c7 ) ZrC powder, 1.3 μm
fC powder, 1.7 μm VC powder, 1.6 μm N
bC powder, 1.5 μm TaC powder, 1.8 μm Mo2C powder, 13 μm (Nb, Ta) N powder (NbN/TaN=1/1 weight ratio, all ratios below mean weight ratio) , 1.7μm (Nb, Ta)C powder (NbC/TaC=1/1), 1.5μm
(Ti, W)C powder (TiC/WC= 3/7
), 2.2 μm (7) ZrCN powder (ZrC/Z
rN = 1/1), 1.5 μm (7) T
1CN powder (TiC/TiN = 3/7) 1.4 μm vCN powder (VC/VN = 1/1), 1
．． 8 μm (Hf, Nb) CN powder (HfC/HfN/
NbC=3/3/4), 2.2 μm Cr powder, 1.6 μm Cr3C2 powder, 1.4 μm
m CrN powder, 1.3 μm CO powder, Oyo and 2
．． Prepare 0 μm Ni powder, blend these raw powders to have the composition shown in Table 1, add 0.4% paraffin based on the total blended powder,
After wet mixing in a ball mill for 3 days and drying, the resulting mixed powder was formed into a green compact under normal conditions, and in a vacuum.
By heating to a temperature of 700°C to volatilize the paraffin, and then sintering in vacuum at the sintering temperatures shown in Table 1, the final composition is substantially the same as the blended composition. Invention cemented carbide alloys 1 to 15 and conventional cemented carbide alloys 1 to 3 were manufactured, respectively.

Next, the thus obtained cemented carbide alloys 1 to 15 of the present invention and conventional cemented carbide alloys 1 to 3 were subjected to an oxidation test, a bending test, a deflection test, a cutting test, and a wire rod rolling test under the conditions shown below. I did it.

(a) Oxidation test The oxidation test was conducted on the present cemented carbide 1 to 7 and the conventional cemented carbide 1.
, 3, the oxidation weight gain was calculated under the following conditions: temperature: 800°C, holding time: 30 minutes, specimen shape: 4 mm x 8 mm x 24 mm.

(b) Bending test The bending test was carried out under the following conditions: temperature: 1000°C, atmosphere: Ar, specimen shape: 4 mm x 8 mm x 24 mm, and distance between fulcrums: 20 mm, using the alloys 1 to 7 of the present invention as in the case of the oxidation test. The transverse rupture strength was measured for conventional alloys 1 and 3.

The results of both tests are shown in Table 2.

As shown in Table 2, the binder phase is composed of Co-Ni-Cr gold alloy, and the hard phase is WC-metal nitride or WC-metal nitride.
In each of the cemented carbide alloys 1 to 7 of the present invention composed of -metal nitride-metal carbide, the binder phase is composed of CO, and the hard phase is W.
It is clear that this material has much better oxidation resistance and higher strength than conventional cemented carbide alloys 1 and 3 made of carbon or WC-metal carbide.

(C) Deflection test The deflection test was conducted under the same conditions as the bending test except that the load was removed when the load reached 200 kg.
1 and conventional cemented carbide 1 and 3, and the amount of deflection was measured.

The measurement results are shown in Table 3.

From the results shown in Table 3, it is clear that the cemented carbide of the present invention has superior plastic deformation resistance compared to conventional cemented carbide.

(d) Cutting test In the cutting test, the work material: SNCM-s (HB: 220
), Chip shape: 5NGN432, Cutting speed: 120
m/min, depth of cut: 1mm, feed: 1.06mm
/re■, Cutting time: 30 seconds, the present invention cemented carbide 12.13 and the conventional cemented carbide 3)
The amount of plastic deformation of the cutting edge was measured.

As a result, the cutting edge of the cemented carbide 12 of the present invention was 0.03 mm,
The cutting edge of the cemented carbide 13 of the present invention exhibits a plastic deformation of 0.05 mm, and the cutting edge of the conventional cemented carbide 3 exhibits a plastic deformation of 0.09 mm. From these results, the cemented carbide of the present invention has excellent plastic deformation. It is clear that it has deformability.

(e) Wire rod rolling test For the wire rod rolling test, a Morgan roll for wire rod rolling was prepared from the present cemented carbide 14.15 and the conventional cemented carbide 2,
A steel material heated to a temperature of 950° C. was rolled using this roll, and the surface state of the first stage roll was observed after processing 500 tons of steel material.

As a result, the rolls manufactured with the cemented carbide 14 and 15 of the present invention have very few thermal cracks and no spalling, whereas the rolls manufactured with the conventional cemented carbide 2 The occurrence of many cracks and spalling was observed, and it is clear that the cemented carbide of the present invention has excellent heat cracking resistance and spalling resistance.

As mentioned above, the WCC cemented carbide of the present invention, the conventional WC
- Even better high-temperature properties than Co-based cemented carbide,
In other words, it has strength, oxidation resistance, spalling resistance, plastic deformation resistance, heat cracking resistance, and wear resistance, so it exhibits extremely excellent performance when used as various cutting tools and wear-resistant tools. It has industrially useful properties.

Claims (1)

[Claims] 1 Contains 2 to 20% of Cr, with the remainder being Ni and CO.
(However, Ni/Co weight ratio = 5/95 to 95/5
): 3 to 30% of a binder phase having a composition of Hard phase with a composition consisting of tungsten and inevitable impurities:
A patented stainless steel-based cemented carbide characterized by comprising the remainder (more than % by weight). 2Cr: Contains 2-20%, the rest is Ni and CO (
However, the weight ratio of Ni/Co = 5/95 to 95/5)
A binder phase having a composition consisting of 3 to 30%, and one or more nitrides of transition metals of Groups 4a and 5a of the periodic table: 1 to 30%; One or more carbides of transition metals in groups 4a and 5a of the Table of Contents and molybdenum carbide: 0.5 to 45
A tungsten carbide-based cemented carbide having excellent high-temperature properties, characterized in that the hard phase has a composition of tungsten carbide and unavoidable impurities;