With the continuous improvement of the global machining level, tool manufacturing technology is also gradually developing. From the aspect of tool materials, modern metal cutting tool materials have evolved from carbon tool steel and high speed steel to today's cemented carbide and cubic nitrogen. Ultra-hard tool materials such as boron make the cutting speed rise from a few meters per minute to kilometers or even 10,000 meters.
With the continuous development of CNC machine tools and difficult-to-machine materials, tools are hard to fight. Good tool materials are required to achieve high speed cutting, dry cutting, and hard cutting. Tool materials play a decisive role in many factors affecting the development of metal cutting.
High speed steel
Since the introduction of high-speed steel in 1900 to 2000, despite the emergence of various super-hard materials, it has not been able to shake the dominance of its cutting tools. After 2000, cemented carbide has become the "natural enemy" of high-speed steel, which is continuing It erodes the market share of high-speed steel tools, but for some tools such as thread cutters and broaching tools that require high toughness, high-speed steel can still compete with hard alloys and even have obvious advantages.
According to statistics from relevant parties, in 2004 China produced 78,000 tons of high-speed steel, accounting for almost 50% of global production, and produced about 2.5 billion pieces of tools, of which nearly 2 billion were exported. In 2005, the national high-speed steel output was 83,000 tons, of which low-alloy high-speed steel (tungsten equivalent 6%~12%) accounted for about 40%. The production and sales of cutting tools were similar to those in 2004. From the overall situation analysis, the most prominent contradiction at present is the vicious expansion of low-end products, and the shortage of high-end products, or high-end failure, low-end melee, if freely developed, the position of high-speed steel tools in the field of cutting will only become more and more Low, even quit, to hand over the market to foreign countries.
People used to divide high-speed steel into four categories:
1) General Purpose High Speed â€‹â€‹Steel (HSS)
HSS represented by W18Cr4V has been brilliant for a century, and has made outstanding historical contributions to China's tool industry. However, due to many drawbacks, it has gradually faded out of the market; the market share of M2 steel has been from the 1990s. 60%~70% dropped to the current 20%~30%; 9341 is China's self-developed HSS, with a market share of about 20%, and other HSS production such as W7 and M7 are relatively low. HSS has accounted for more than 60% of the total high-speed steel. Due to the excellent toughness and high wear resistance and red hardness of HSS, in the field of tools such as taps and broaches, a site will be firmly held, but the position will be reduced year by year.
2) High performance high speed steel (HSS-E)
HSS-E is a steel grade in which alloy elements such as Co and Al are added to the HSS component, and carbon content is appropriately increased to improve heat resistance and wear resistance. The red hardness of this type of steel is relatively high. After 625 Â°C Ã— 4h, the hardness is still above 60HRC, and the durability of the tool is 1.5~3 times that of the HSS tool.
The output of HSS-E represented by M35 and M42 is increasing year by year. 501 is a high-performance high-speed steel produced in China. It is widely used in forming milling cutters and end mills, and it is also successful in complex tools. Due to the rapid development of CNC machine tools, machining centers, and highly difficult-to-machine materials, HSS-E tool materials are gradually increasing.
3) Powder high speed steel (HSS-PM)
Compared with smelting high speed steel, the mechanical properties of HSS-PM are significantly improved. Under the same hardness conditions, the strength of the latter is 20%~30% higher than that of the former, and the toughness is increased by 1.5~2 times, which is very common in foreign countries. In the 1970s, China developed a variety of HSS-PMs and put them into the market, but somehow they died. Now the materials used in various tool factories are imported. It is gratifying to note that Heye Technology Co., Ltd. (formerly Hebei Metallurgical Research Institute) has been able to produce HSS-PM and supply it in small quantities with good results. Due to the depletion of resources and the excellent comprehensive performance and market demand of HSS-PM itself, HSS-PM will definitely make a big progress.
4) Low alloy high speed steel (DH)
Due to the shortage of alloy resources, the need for a set of twist drill exports and low-speed cutting tools, steel mills and tool factories jointly developed DHs of various brands such as 301, F205 and D101. In 2003, China produced 60,000 tons of high-speed steel. DH 20,000 tons, accounting for 1/3 of high-speed steel; DH accounted for 40% of high-speed steel in 2004, and still showed growth in 2005 and 2006. However, there is a lot of water, some of which are not high-speed steel at all, and the hardness is less than 63HRC, which is also marked HSS.
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