In 1898, American mechanical and management engineer TaylorF.W. and metallurgist WhiteM. developed and invented high-speed steel and performed systematic cutting tests. At that time, they determined that the high-speed steel composition was C-0.67%, W-18.91%, Cr-5.47%, Mn-0.11%, V-0.29%, F-balance, which was very close to the later W18Cr4V composition.

High-speed steel cutters can cut steel at a speed of 30m/min. The efficiency is several times higher than that of carbon tool steel and alloy tool steel used in the past, which has won huge economic benefits for the mechanical industry in the United States at that time. The thermoplasticity of W18Cr4V high-speed steel is not good. Due to the need of hot-rolling process of twist drill, W6Mo5Cr4V2 high-speed steel was successfully developed. In addition, W9Mo3Cr4V was also produced. These three high-speed steels have similar cutting performance and mechanical properties and are called general-purpose.

After the middle of the 20th century, science and technology developed rapidly, various difficult-to-machine materials continued to emerge, and the performance of general-purpose high-speed steel was no longer used. So high-performance high-speed steel and powder metallurgy high-speed steel appeared one after another, which made the performance of high-speed steel tool materials get Greatly improved. Because the high-speed steel tool has good comprehensive performance and better machinability than other tool materials, all kinds of tools can be made of high-speed steel, and its performance is continuously improved, so it is still one of the most used tool materials.

In recent years, the annual output of high-speed steel in the world is about 160,000 to 220,000 tons, and the annual output of high-speed steel in China has reached 50,000 to 60,000 tons. Heye Technology Co., Ltd. and Jiangsu Tiangong Tools Co., Ltd. are large domestic producers of high-speed steel, which account for a large share of the national high-speed steel production.

<br> <br> speed steel high-performance on the basis of the general-purpose high-speed steel, by adjusting the chemical composition and substantially add other alloying elements, so as to obtain room temperature and high temperature mechanical properties significantly improved.

1) High Speed Steel <br> <br> W18Cr4V increase of 0.2% based on the carbon content, formed 95W18Cr4V, according to the chemical equilibrium theory of carbon, carbon may be added in the high speed steel of austenite during quenching, strengthen Diffusion hardening during tempering, thereby increasing the normal temperature and high temperature hardness. Compared with W18Cr4V, the wear resistance and tool durability of 95W18Cr4V are improved, and the sharpening performance is equivalent. Although the cutting performance of this steel is not as high as that of cobalt and vanadium high-speed steel, but the price is cheap, the cutting edge can be sharpened sharply, so it has application value. Similarly, there are 100W6Mo5Cr4V2 (CM2) high carbon high speed steel, but this high performance high speed steel is not used much.

2) High cobalt high speed steel

Cobalt in high-speed steel can promote the precipitation of tungsten and molybdenum tungsten carbide from martensite during tempering, improve the dispersion hardening effect, and improve the thermal stability, so it can improve the normal temperature, high temperature hardness and wear resistance. Increasing the cobalt content can also improve the thermal conductivity of steel and reduce the friction coefficient between the tool and the workpiece. M42 is a representative steel grade in the United States, and its comprehensive performance is superior. Sweden's HSP-15 is also a steel of this type, but its vanadium content is 3%, and the sharpening processability is not as good as M42. High cobalt content and high price are not suitable for China's national conditions. Co5Si, a low-cobalt-containing high-speed steel developed in China, has superior performance, and its price is lower than that of M42 and HSP-15. However, the vanadium content of Co5Si is also 3%, and the sharpening processability is also poor, so it is not suitable to use it to make the blade shape complicated. Tool.

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