Rapid tool steel is mainly used in makes various cutting tools, mould and wear-resisting component of machine, makes the different of hardness after the cutter thermal treatment and working conditions according to it, is divided into universal high speed tool steel and very hard high-speed tool steel two big classes again.In general, the rapid tool steel that be used for general machining of the tempered-hardness of quenching below HRC66, be called the universal high speed tool steel, and quench tempered-hardness more than HRC66 be used for hard-cutting material processing or precision machined high-speed tool is called very hard high-speed tool steel.In fact so-called very hard high-speed tool steel is exactly that hardness is higher, red hardness is better, wear-resisting, corrosion resistant rapid tool steel.At present, very hard high-speed tool steel commonly used mainly contains two kinds, a kind of is the cobalt-containing super-hard rapid tool steel that adopts smelting process to produce, this class very hard high-speed tool steel cobalt contents is higher, generally all on 5% (weight %), high rigidity is mainly derived from composition, therefore claims that it is the cobalt rapid tool steel, in this class very hard high-speed tool steel, the most frequently used trade mark is W2Mo9Cr4VCo8 (being called for short M42) at present; The another kind of special methods that adopts is manufactured as powder metallurgic method, particle metallurgy method etc., and this class very hard high-speed tool steel according to trade mark difference, can contain cobalt or not contain cobalt, and its high rigidity is mainly derived from the good metallurgical structure that manufacturing process brings.Owing to contain higher cobalt, and cobalt is that strategic resource, price are higher in the last class very hard high-speed tool steel, so cost is also just higher.Then a class very hard high-speed tool steel makes production cost increase owing to adopted special manufacturing process.Therefore, the cost of steel is also just higher.Along with the develop rapidly of mechanical industry, the requirement of very hard high-speed tool steel is increased day by day.Therefore, the material supplier authors are in that to seek manufacturing process comparatively easy, the very hard high-speed tool steel that the prices of raw and semifnished materials are comparatively cheap again.
The low-cobalt very hard high-speed tool steel that it is W10Mo4Co3 that the present invention proposes a kind of nominal trade mark, its cobalt contents is 3.0% (weight %), do not need to adopt special manufacturing process, and adopt common melting-esr-forging-rolling or melting-forging-rolling technology, when producing big timber stock or under the enough situation of ratio of forging reduction, also can directly forge and become a useful person, and can be drawn into a material as required.The concrete Chemical Composition (weight %) of W10Mo4Co3 very hard high-speed tool steel of the present invention is:
C 0.80-1.40, Si 0.20-0.60, Mn 0.10-0.60, P≤0.03, S≤0.03, Cr 3.60-4.60, V 1.00-1.60, W 8.00-12.00, Mo 4.00-6.00, Co2.50-3.50, surplus is Fe.
Rapid tool steel will reach superhard level, must increase carbon content and alloy degree in the austenite, makes it when tempering subsequently, and proeutectoid carbide is separated out in disperse, thereby obtains high rigidity.Carbide type, size, form and distribution etc. directly have influence on a series of performances such as the hardness, toughness, red hardness of rapid tool steel.For obtaining high rigidity, very hard high-speed tool steel of the present invention further improves W content on the basis of universal high speed tool steel, and corresponding raising C content guarantees that to balance drawing process has competent proeutectoid carbide to separate out.The most frequently used in the cobalt-containing super-hard rapid tool steel is W2Mo9Cr4VCo8 (being called for short M42) steel, and by discovering, the reason that easily produces tiny crack in the M42 steel mainly is that Mo content is higher, its as cast condition carbide M
2C is difficult to decompose, and remains in the steel, and these carbide size are big, and out-of-shape easily produces tiny crack, thereby the toughness of steel and plasticity are reduced.The present invention adopt W-Mo be steel to replace Mo be steel, and W content is not less than Mo content, such W, Mo proportioning, making the as cast condition eutectic carbides (mainly is M
2C) decompose easily in heat treatment process, thereby carbide particle is thinner, the over-all properties of steel is better.In addition for reducing cost, under the prerequisite that guarantees the very hard high-speed tool steel performance, reduce cobalt contents, because the reduction of cobalt contents, and cause very hard high-speed tool steel degradation part, then the adjustment by above-mentioned composition is replenished, make it guarantee the cobalt-containing super-hard rapid tool steel W2Mo9Cr4VCo8 at present commonly used performance index of (being called for short M42) on the whole, every performance index of low-cobalt very hard high-speed tool steel of the present invention have been met or exceeded among the standard GB 9943-88 the requirement of M42, be specially adapted to replace M42 and be used for hard-cutting material processing and precision sizing.
Low-cobalt very hard high-speed tool steel of the present invention adopts the common iron production method, promptly adopt electric arc furnace or induction furnace melting, casting ingot-forming forges then and becomes a useful person or hammer cogging, rerolls and makes material, also can be before forging, increase electroslag remelting process one, ingot quality raising, material are purified, tissue improves, forge behind the esr become a useful person or hammer cogging after, reroll and make material.Also can in forging, rolling or follow-up drawing are processed, make it be configured as required bar, sheet material, special-shaped vertical bar material, block material or silk material as required.The forging rolling temperature of steel is 1050 ℃-1200 ℃, and the finish-forging finishing temperature is greater than 900 ℃, and the annealing temperature of finished steel is 800 ℃-900 ℃, and quenching temperature is 1150 ℃-1250 ℃, and tempering temperature is 500 ℃-600 ℃.
Low-cobalt very hard high-speed tool steel of the present invention, the tempered-hardness of quenching can reach HRC66.5-69, and 600 ℃ red hardness can reach HRC66, a
kValue is 15-251/cm
2, σ
BbBe 1800-2600N/mm
2Cutting test shows that at cutting speed Vc=20m/min, the blunt standard is got V
BThe cutter life of M42 is 118min under the situation of=0.25mm, and low-cobalt very hard high-speed tool steel of the present invention is 128min.At cutting speed Vc=30m/min, the blunt standard is got V
BUnder=0.3mm the situation, the cutter life of M42 is 40min, and low-cobalt very hard high-speed tool steel of the present invention is 50min.
Embodiment:
According to low-cobalt very hard high-speed tool steel composition of the present invention, adopt induction furnace melting, its concrete Chemical Composition is as shown in table 1, smelts after esr hammer cogging, be rolled into the garden bar, after heat treatment, by the national standard sampling, the tempered-hardness of quenching, red hardness, bending strength and impelling strength are measured, its result lists table 2, table 3, table 4 respectively in, for ease of relatively, the M42 steel is also together listed in the corresponding table in the test data of the same terms.
Table 1: the chemical ingredients of low-cobalt very hard high-speed tool steel of the present invention
| | ??C | ??Mn | ????S | ????P | ??Si | ??Cr | ??V | ??W | ??Mo | ??Co |
| ?1# | 1.22 | ?0.26 | ?0.026 | ?0.026 | ?0.01 | ?4.32 | 1.44 | 10.41 | ?5.54 | ?2.81 |
| ?2# | 1.01 | ?0.28 | ?0.028 | ?0.028 | ?0.11 | ?4.09 | ?1.19 | ?9.33 | ?5.15 | ?2.80 |
| ?M42 | 1.05 -1.15 | ?0.15 ?-0.40 | ≤0.030 | ?≤0.030 | ?0.15 -0.65 | ?3.50 -4.25 | ?0.95 -1.35 | 1.15 -1.85 | ?9.00 -10.00 | ?7.75 -8.75 |
Table 2: low-cobalt very hard high-speed tool steel of the present invention quench tempering temperature and hardness relation (differing temps is quenched, 550 ℃ of tempering * 1h * 3 time) (HRC of unit)
| | ??1170℃ | ??1190℃ | ??1210℃ | ??1230℃ |
| ????1# | ????67.0 | ????68.0 | ????68.5 | ????69.0 |
| ????2# | ????66.5 | ????67.0 | ????67.5 | ????68.0 |
| ????M42 | ????68.0 | ????68.5 | | |
Table 3: low-cobalt very hard high-speed tool steel red hardness of the present invention (HRC of unit)
| Temperature (℃) | ??600℃ | ??625℃ | ??650℃ |
| ??1# | ??66.0 | ??59.5 | ??54.5 |
| ??2# | ??66.0 | ??59.0 | ??54.0 |
| ??M42 | ??66.0 | ??58.0 | ??52.0 |
Table 4: very hard high-speed tool steel bending strength of the present invention and impelling strength
| | Bending strength N/mm
2 | Impelling strength T/cm
2 |
| ????1# | ????2500 | ????24 |
| ????2# | ????2450 | ????23 |
| ????M42 | ????2500 | ????18 |