High speed tool steel is mainly used for cutting tool manufacturing efficiency. Because of its high red hardness, good wear resistance, high strength characteristics, also used in the manufacture of high performance requirements of the mold, roller, bearing and high temperature hot spring. High speed tool steel by heat treated using hardness up to HRC63, can still keep high hardness in 600 ℃ temperature, but its toughness, wear resistance and heat resistance are good. The main alloy elements of high speed tool steel annealing state how, molybdenum, chromium, vanadium,and some high speed tool steel with cobalt, aluminum etc.. This kind of steel is a high carbon high alloy ledeburite steel, one of the main characteristics of the organizations contain a large amount of carbides. The as cast high speed tool steel carbide is eutectic carbide, the thermal pressure processing and then crushed into granulardistribution in steel, known as a secondary carbide precipitation; from austenite and martensite carbide known as the two. Great influence on the performance of these carbides in high speed tool steel, especially the two carbide, has great influence on steel austenite grain size and two times the hardening properties. Chemical composition ofcarbide quantity, type and steel, and the deformation of particle size and distribution of carbides and steel related.Tungsten, molybdenum is the main alloy element in high speed tool steel, plays an important role in the twohardened steel and other properties. Chromium on the hardenability of the steel, oxidation resistance and wear resistance plays an important role, also has a certain effect on the two secondary hardening. Vanadium steel twohardening and wear resistance plays an important role, but reduce the grinding performance.

High speed tool steel quenching temperature is very high, close to the melting point, its purpose is to make the alloy carbide more dissolved into the matrix, the two hardening ability makes the steel has better. High speed tool steel after quenching hardness rise, this is the first time hardening, but the higher the quenching temperature, temperingis the lower strength and toughness. After quenching and low temperature under 350 ℃ tempering hardness decreased at temperatures above 350 DEG C tempering hardness increases gradually, to the range of 520~580 ℃tempering (chemical composition is different, the tempering temperature of different hardness peak) occurred second times, and more than quenching hardness, this is the two time hardening. This is an important characteristic of high speed tool steel.

High speed tool steel has the red hardness, wear resistance, high hardness and other performance, but also has some thermoplastic, grinding process performance.

Elements series high speed tool steel alloy is tungsten, molybdenum containing or not containing a small amount ofmolybdenum. Its main characteristic is overheating sensitivity, decarburization sensitivity of small, heat treatment andthermal processing temperature range is wide, but coarse carbide particles, distribution uniformity, impact toughnessand plasticity.

The main alloy elements of W-Mo high-speed tool steel tungsten and molybdenum. Its main characteristic is theparticle size and distribution of carbides are better than that of tungsten series high speed tool steel,decarbonization and overheating sensitivity than molybdenum high speed tool steel, the use of performance and process performance are good.

The main alloying element molybdenum high speed tool steel, molybdenum, tungsten containing or not containing a small amount of tungsten. Its main characteristic is fine carbide particles, uniform distribution, good toughness, but the decarbonization and overheating sensitivity high, narrow range of thermal processing and heat treatment.

Cobalt high speed tool steel is added with a certain volume based on universal high-speed tool steel on the cobalt,can significantly increase the hardness, wear resistance and toughness.

Powder is not high speed tool steel is produced by powder metallurgy method without. Firstly, the oxygen atomizationof high speed tool steel pre alloyed powder is not cold, heat, and then use the static press will not be billet powdercompaction densification, after forging, rolling material. Fine carbides, distribution is not uniform powder high-speed tool steel, toughness, grindability and dimensional stability are very good, can be produced by casting a possiblehigher content of alloy elements superhard high speed tool steel. Powder is not high speed tool steel can be divided into 3 categories, the first category is cobalt high speed tool steel, its characteristics are close to the hardness of the hard alloy, but also has good ductility, workability, grindability and toughness. The second category is tungsten,molybdenum, cobalt free high vanadium high speed tool steel. The third category is the super wear-resistant high speed tool steel. Its hardness is not too high, but the excellent wear resistance, mainly for high wear resistance andwithstand the impact load working conditions.