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. 

 The application of high-speed tool steel is a high-speed tool steel of high carbon alloy tool steel, wC = 0.70 ~ 1.25%, often by adding the alloying elements W, Mo, Cr, V, etc., W, Mo, V is to improve the hot hardness of the major elements, V can form a 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. 
 Classification of high speed tool steel 
 Including high-speed tool steel drill is universal high-speed tool steel on the basis of adding a certain amount of cobalt, can significantly increase the hardness, wear resistance and toughness. Powder high speed tool steel is produced using powder metallurgy method. First Preparation of hypoxia with high-speed tools atomized pre-alloyed steel powder, then cold, hot isostatic press to fulfill dense compacted powder billet, and then by forging, rolling lumber. Powder 
 High-speed tool steel 
 The end of high-speed tool steel carbide small, evenly distributed, toughness, dimensional stability etc grinding and good produce ingot method with a higher content of alloying elements may have the super-hard high-speed tool steel. Powder high speed tool steel can be divided into three categories, first is cobalt high speed tool steel, which is characterized by close to the hardness of cemented carbide, but also has good malleability, machinability, grindability and toughness . The second category is no high tungsten cobalt, molybdenum, vanadium super-hard high-speed tool steel. The third category is super wear-resistant high-speed tool steel. Its hardness is not too high, but the excellent wear resistance, mainly used for high wear and shock loading conditions of work. High-speed steel contains alloying elements can be classified according to: ① Tungsten High Speed ??Steel (W 9 ~ 18%), ② tungsten molybdenum high speed steel (W5 ~ 12%, Mo 2 ~ 6%), ③ high molybdenum high speed steel ( W 0 ~ 2%, Mo 5 ~ 10%). Faculties and the amount of vanadium can be divided into general vanadium content (V 1 ~ 2%) and high vanadium content (V 2.5 ~ 5%). Any high-speed steel, such as cobalt (Co 5 ~ 10%) when they classified cobalt high speed steel. HSS-use can be integrated into general-purpose high-speed steel and two types of special purpose high speed steel. Universal high-speed steel is widely used for a variety of common metal cutting tools (such as drills, taps, saw blade) and precision tools (such as hobs, shaper cutters, broaches). Hardness cutting material is generally HB ≤ 300. Special purpose high-speed steel can be divided into high-vanadium high speed steel, usually cobalt high speed steel and super-hard type (HRC 68 ~ 70) high-speed steel (Table 2). Main purpose is to create high-speed high-speed steel cutting tools, in addition to high hardness (typically greater than HRC 63, high up HRC 68 ~ 70), high wear resistance and sufficient toughness, but also under high speed cutting blade is not due to heating and softening of the heat resistance. Heat is usually hard to measure with the red, that is 580 ~ 650 ℃ heating the steel has 4 times, each holding 1 hour air-cooled, and then at room temperature measured hardness value. High-speed steel toughness and impact bending strength is usually measured by value. In recent years, high-speed steel used in manufacture of cold-working die, mainly in the use of performance requires a high compressive yield strength, high wear resistance and high toughness, while the heat resistance is less demanding and therefore can be used to lower temperature quenching.