High speed steel(HSS) is the tool steel with high hardness, high wear resistance, and high heat resistance. High speed steel has good process performance, strength, and toughness. So, it is mainly used to made complex thin-blade and impact-resistant metal cutting tools, as well as high-temperature bearings and cold extrusion molds.
The heat treatment process of high speed steel is complicated and must suffer a series of processes such as quenching and tempering. When quenching, it is generally carried out in two stages due to its poor thermal conductivity. Preheat at 800 ~ 850 ° C, then quickly heat to the quenching temperature of 1190 ~ 1290 ° C (different steel grade with different temperature), then use the way of oil cold, air cooled and etc. All factories use salt furnaces to heated, however, the vacuum furnaces are widely used right now. After quenching, some of the retained austenite remains in the internal structure and does not transform into martensite, which affects the performance of high speed steel. In order to change the retained austenite and further improve the hardness and wear resistance, it is generally carried out 2 to 3 times of tempering under 560 ° C.
High speed steel production and manufacturing methods: it usually produced by an electric furnace. High-speed steel was produced by powder metallurgy method, make the carbides are evenly distributed on the substrate, which would improve the time of use.
It always used in the manufacture of various cutting tools. Such as turning tools, drill bits, hobs, machine saw blades and high requirement molds.
High speed steel grades:
AISI: T1, T4, M2
JIS: SKH2, SKH51