About high-speed tool steel 
 Forming principle 
 High-speed tool steel is mainly used to manufacture high-efficiency cutting tools. Because of its high red hardness, wear resistance, high strength characteristics, but also for the manufacture of high performance requirements of the mold, roll, high temperature bearings and high temperature springs 
 High-speed tool steel 
 And so on. High-speed tool steel after heat treatment than the use of hardness up to HRC63, at about 600 ℃ work temperature and still maintain a high hardness, and its toughness, wear resistance and heat resistance are good. High-speed tool steel annealed state the main alloying elements tungsten, molybdenum, chromium, vanadium, and some high-speed tool steel added cobalt, aluminum and other elements. These are high-carbon high-alloy steel ledeburite steel, its main feature of the organization is rich in carbon. Cast high-speed tool steel in the eutectic carbide is a carbide, broken by heat stress after processing into granular distributed in the steel, as a carbide; martensite from austenite and carbide precipitation in the matrix that for the secondary carbides. The carbide tool steel for high-speed performance of great impact, especially in the secondary carbides, its steel austenitic grain size and the performance of secondary hardening, etc. have a great impact. Carbon number, type and chemical composition of steel, and carbide particle size and distribution are concerned with the deformation of steel. Tungsten, molybdenum high-speed tool steel is the main alloying elements, secondary hardening of steel and other properties play an important role. Chromium on steel hardenability, wear resistance and oxidation resistance plays an important role in the secondary hardening also has a role. Vanadium on secondary hardening and wear resistance of steel play an important role, but can reduce the grinding performance. 
 Physical properties 
 High-speed tool steels the quenching temperature is high, close to the melting point, its purpose is to enable more integrated into the alloy carbide matrix, the secondary hardening steel has better ability. High-speed tool steel after quenching hardness increased, this is the first hardened, but the higher the quenching temperature, the strength and toughness after tempering lower. After quenching and tempering at 350 ℃ the following drop in hardness at temperatures above 350 ℃ tempered hardness gradually increased to 520 ~ 580 ℃ range of tempering (different chemical composition, tempering temperature difference) appears second hardness peak, and more than quenching hardness, this is the secondary hardening. This is an important feature high-speed tool steel. In addition to high-speed tool steel with high hardness, wear resistance, red hardness and other performance, but also has a certain thermoplastic, grinding and other process performance can be. Tungsten high speed tool steel is the main alloying elements tungsten, molybdenum, or with a small amount of free molybdenum. Its main feature is the small thermal sensitivity, sensitivity to small decarburization, heat treatment and thermal processing of a wide temperature range, but the carbide coarse particles, uniformity is poor, the impact toughness of the steel and plastic. Tungsten-molybdenum high-speed tool steel is the main alloying elements tungsten and molybdenum. Its main feature is the carbide particle size and distribution are better than tungsten high speed tool steel, heat sensitivity and sensitivity of decarburization than molybdenum high-speed tool steel, the use of performance and process performance are good. Molybdenum high-speed tool steel is the main alloying elements molybdenum, tungsten, or with a small amount of tungsten-free. Its main feature is the fine carbide particles, distribution, good toughness, but the sensitivity and thermal sensitivity of decarburization large, narrow thermal processing and heat treatment. 
 Applications 
 Mainly used to manufacture high speed steel, high-speed cutting tools, such as turning, milling cutter, reamer, broach, twist, etc. 

 ) Used high-speed steel 
 High-speed tool steel is a high-carbon high alloy tool steel, wC = 0.70 ~ 1.25%, often by adding alloying elements are W, Mo, Cr, V, etc., W, Mo, V is to improve the hot hardness of the main elements, V can be the formation of high hardness of carbides, significantly increased the hardness and wear resistance of steel, Cr can improve the hardenability. W18Cr4V, W6Mo5Cr4V2 and W9Mo3Cr4V for the more commonly used high-speed steel, three steel production now accounts for domestic production and use of more than 95%. 
 Heat treatment 
 W18Cr4V final heat treatment of steel for the high-temperature quenching and multiple tempering. W18Cr4V steel quenching temperature up to 1270 ~ 1280 ℃, obtained after quenching martensite, carbides and residual austenite (20% to 30%). Three times using 560 ℃ tempered tempering, many times the main purpose of tempering is to eliminate quenching in more residual austenite to martensite into; three tempered martensitic precipitation can make more carbides, resulting in secondary hardening, increase heat rigid. High-speed steel hardness after heat treatment up to 63 ~ 65HRC. High-speed steel is ledeburite steel, cast a thick fish bone tissue-like alloy carbide, carbide hard and brittle that, if not eliminate the heterogeneity of this carbide, the tool will be made of early damage , the tool prone to "chipping", it must be repeated be crushed forging method, the refinement and uniform distribution of carbides in the matrix. W18Cr4V steel annealed after forging to eliminate stress, reduce the hardness to improve the cutting performance and good organization and preparation for the quenching.