High-speed steel (HSS) is a tool steel with high hardness, high wear resistance and high heat resistance, also known as high-speed tool steel or front steel, commonly known as white steel. High-speed steel was created in 1898 by F.W. Taylor and M. White in the United States.
High-speed steel has good process performance, good strength and toughness, so it is mainly used to manufacture complex thin-edged and impact-resistant metal cutting tools, as well as high-temperature bearings and cold extrusion dies. In addition to the high-speed steel produced by the smelting method, powder metallurgy high-speed steel appeared after the 1960s, which has the advantage of avoiding the reduction of mechanical properties and heat treatment deformation caused by the segregation of carbides produced by the smelting method.
The heat treatment process of high-speed steel is more complicated, and it must go through a series of processes such as quenching and tempering. Quenching is generally carried out in two stages due to its poor thermal conductivity. First preheat at 800~850°C (to avoid causing large thermal stress), then quickly heat to quenching temperature of 1190~1290°C (the actual temperature of different grades is different), and then oil cooling or air cooling or gas cooling. The factories are all heated by salt furnaces, and vacuum furnaces are also widely used. After quenching, a part (about 30%) of retained austenite remains in the internal structure and is not transformed into martensite, which affects the performance of high-speed steel. In order to transform the retained austenite and further improve the hardness and wear resistance, it is generally necessary to carry out 2 to 3 tempering times, the tempering temperature is 560 ° C, and the holding time is 1 hour each time.
Production method: It is usually produced by electric furnace, and high-speed steel is produced by powder metallurgy method, so that the carbides are evenly distributed on the substrate in the form of extremely fine particles, which improves the service life.
Uses: used in the manufacture of various cutting tools. Such as turning tools, drills, hob, machine saw blades and molds with high requirements.