The development of tool materials has gone through five stages: tool steel, high-speed steel, cemented carbide, ceramics and superhard materials. Tool materials for high-temperature alloy cutting are selected from the latter four categories.
Ⅰ.High performance high speed steel
(1)M42(W2Mo9Cr4VCo8)
M42 is the most important steel grade used in superalloy cutting and manufacturing precision forming tools all over the world. Its main advantage is that it has high hardness while maintaining good grindability. When the hardness is HRC68-69, M42 can still be ground with ordinary corundum abrasives. The grinding efficiency is similar to that of general high-speed steel (W18Cr4V and W6Mo5Cr4V), and the grinding finish is relatively high. The disadvantage of M42 is that the bending strength and toughness are lower than those of general-purpose high-speed steel, and the tendency to precipitate carbides is large during quenching and cooling. When the amount of carbide precipitation is large, it will affect the hardness and red hardness of the steel. For this reason, the heat treatment process of M42 is more complicated.
M42 high-speed steel is mainly used for milling, drawing, drilling, tapping and forming of nickel-based high-temperature alloys, and the processing effect is very good. Drilling holes in cast high-temperature alloy K401 workpieces, the durability of M42 drills is 4-6 times higher than that of W18Cr4V. K401 is equivalent to the AHB-300 alloy of the former Soviet Union. It is a Ni-based cast high-temperature alloy containing 8.5% W and 6.5% of the sum of Al+Ti. It can manufacture gas turbine turbine guide blades working at 900°C; tapping on GH4037 alloy , the tap life can be increased by 2.5-18 times.
HSP-15 is the earliest developed super-hard high-speed steel. Its hardness, red hardness and toughness, especially wear resistance are better than M42. The heat treatment performance is also good: the quenching temperature range is wide, it is not easy to overheat, and the decarburization tendency is low. Its disadvantage is that its grindability is poor, and it is mainly used for single-edged tools. HSP-15 high-speed steel milling deformed superalloy GH4037 arc-shaped conical surface, the durability of the milling cutter is 2-6 times higher than that of general high-speed steel W18Cr4V.
(3) M2Al(W6Mo5Cr4V2Al)
The advantages of this kind of steel are: low price, less likely to produce built-up edge on the cutting edge, good wear resistance, and high processing smoothness. Its disadvantages are: grain growth, oxidation, and decarburization tend to be large, and more residual austenite is retained in the quenched state, which makes the forging heat treatment process complicated, and the grindability is poor. Single crystal corundum, praseodymium neodymium abrasives or cubic nitrogen are used Boron grinding wheel grinding. M2Al taps tapped holes on deformed high-temperature alloy GH2135, and its tap life is more than five times longer than that of W18Cr4V. For example, when drilling, the drill bit life is increased dozens of times.
(4) V3N steel (W12Mo3Cr14V3N)
V3N steel is a cobalt-free super-hard high-speed steel that was successfully developed and put into industrial production in the early 1980s. Its advantages are: in addition to showing comprehensive excellent performance when cutting high-temperature alloys, there are no difficulties in metallurgy, forging, heat treatment and other processes, and it is close to W18Cr4V steel. The hardness of V3N steel is similar to M42 and HSP-15 (HRC67-69), but its toughness is better. Its temper softening resistance is not lower than or slightly higher than that of cobalt-containing steel, and its high-temperature hardness is slightly lower than that of cobalt-containing steel. Therefore, when processing high-temperature alloys, cobalt-free superhard high-speed steel is suitable for interrupted cutting, low-speed finishing or situations where the rigidity of the machine tool-tool system is not good. Turning nickel-based superalloy GH118, V3N steel is equivalent to M42.
(5) Powder metallurgy high speed steel
In recent years, the biggest change in high-speed steel is the development of powder metallurgy high-speed steel. The fine high-speed steel powder obtained by atomizing molten high-speed steel with high-pressure nitrogen gas is sealed and sintered in a vacuum state. The problem of coarse carbide segregation is to obtain extremely fine grains smaller than 0.002mm.
Powder metallurgy high speed steel has good mechanical properties. For example, the powder metallurgy high-speed steel with the brand name CPMT15 has 2-2.5 times the strength and toughness of the smelted high-speed steel with the same chemical composition; the high-temperature hot hardness is 0.5-1HRC higher than the smelted high-speed steel, and the wear resistance is 20%- 30%. Therefore, powder metallurgy high-speed steel cutting tools are suitable for intermittent cutting, high strength and sharp cutting edges, cutting under high dynamic loads, and are suitable for manufacturing large-scale cutting tools, precision cutting tools, and complex cutting tools. When turning cast high-temperature alloy K214, the durability of domestic powder high-speed steel GF3 is 7 times higher than that of W18Cr4V tool, and turning GH4169 is 2 times higher.
Crucible Company of the United States, Kobe Steel Works of Japan, Hitachi Metals Company, 0SG Company of Japan, NACHI Company, etc. can provide nearly 20 kinds of powder metallurgy high-speed steel, while my country’s steel mills can provide fewer varieties. It is believed that powder metallurgy high-speed steel will bring new development opportunities for my country’s metal processing industry.
(6) Coated high-speed steel cutting tools
The traditional coated high-speed steel cutting tool uses physical vapor phase technology (PVD) to deposit a 2-5mm thick titanium nitride (TiN) thin layer on the surface of the high-speed steel cutting tool. Its hardness can reach 2000HV and it has high wear resistance. . In recent years, new technologies such as ZrN, HfN, CrN, TiAlN, diamond carbon coating, and composite coating have been developed, which not only improve the durability of the tool, but also process difficult-to-machine alloys such as high-hardness alloys and high-temperature alloys. Material.
Ⅱ. Carbide
Cemented carbide began to be produced in Krupp in Germany in 1926. Due to its unique advantages, it has developed greatly in terms of production volume, quality and application range. As a metal cutting tool material, the normal temperature hardness of high-speed steel is HRC63-70 (HRA83-86.6), while the hardness of cemented carbide can reach HRA89-94. The heat-resistant temperature of high-speed steel is 550-650°C, while that of cemented carbide is 800-1000°C. At 600°C, the hardness of cemented carbide exceeds that of high-speed steel at room temperature, so the durability of cemented carbide tools is dozens of times higher than that of high-speed steel, and the cutting speed can be increased several times. At present, cemented carbide tools account for about 30% of the total cost of tools, while the amount of metal removal (calculated by volume) accounts for about 70%. With the improvement of the quality of cemented carbide and the level of tool manufacturing technology, some complex forming tools such as hobs, broaches, etc. also use cemented carbide, so that the proportion of cemented carbide tools is increasing.
(1) Classification of cemented carbide
According to the composition of cemented carbide, there are four types of cemented carbide in my country: tungsten-cobalt (YG). This type of alloy uses WC as the hard phase and Co as the binder phase. Commonly used grades include YG3, YG6, YG6X, YG8, etc.; tungsten titanium cobalt (YT). This type of alloy uses WC and TiC as the hard phase and Co as the binder phase. Commonly used grades include YT5, YT14, YT15, YT30, etc.; adding ingredients such as TaC or NbC to the above two types of alloys forms a new type of cemented carbide. Adding TaC (or NbC) to YG alloys includes YG8N, YG6A, 813, YGRM, etc. Adding TaC (or NbC) to YT alloys includes YW1, YW2, YW3, YW4, YTM30, 643M, 726, 767, etc. Adding TaC (or NbC) to YG alloys can significantly improve its normal and high temperature hardness, high temperature strength, and wear resistance, but the bending strength is slightly reduced. Adding TaC (or NbC) to YT alloys can significantly improve the flexural strength and impact toughness, and can also improve heat resistance, wear resistance and thermal shock resistance; titanium carbide-based hard alloys, such alloys use TiC as the The main components are Ni and Mo as the binding phase. There are YN05, YN10, 715, etc. The properties of this type of alloy are between ordinary cemented carbide and ceramics, and some people call them cermets. Its advantages are: high hardness, good wear resistance, strong crater wear resistance and oxidation resistance, and high chemical stability. Its disadvantages are: low elastic modulus, poor resistance to plastic deformation, low bending strength, easy edge chipping, and not suitable for low-speed cutting.
If divided by the grain size of carbides, cemented carbide can be divided into three categories: coarse grains (such as YG8C), fine grains (such as YG6X) and ultra-fine grains. Ultra-fine grains refer to the average size of carbide grains below 1 micron (some say 0.5 microns). This type of alloy has high strength, hardness, heat resistance and good low-speed cutting properties.
In addition to the above-mentioned cemented carbide, there is also a steel-bonded cemented carbide. Its hard phase is still WC or TiC, but the bonding phase is alloy steel. Its main feature is that it can be processed and then hardened like high-speed steel. It is mainly used for molds, and it can also be used to make forming tools. Its cutting performance is between high-speed steel and cemented carbide [1].
(2) Examples of carbide blade selection
YS2 (YG10HT) blades of this grade have good performance in processing nickel-based high-temperature alloys. Such as processing U500, use YS2, YCRM, YH1, 643M, YW4, 798 six kinds of blades to compare in three speed ranges of V1=15-13m/min, V2=17-14.7m/min, V3=29-26m/min , both YS2 has the highest durability, followed by YGRM. YS2 contains 87.5%WC, 2%TaC, 0.5%Cr3C4 and 10%Co.
Tianjin Anton Metal Manufacture Co., Ltd. is a company specializing in the production of various nickel-based alloys, Hastelloy alloys and high-temperature alloy materials. The company was established in 2001 with a registered capital of 16.8 million, specializing in the production and sales of alloy materials. Anton Metal’s products are widely used in aerospace, chemical industry, electric power, automobile, nuclear energy and other fields, and can also provide customized alloy material solutions according to customer needs. If you need to know the price consultation of alloy materials or provide customized alloy material solutions, please feel free to contact the sales staff.
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Post time: Sep-02-2023
