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 of 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. Its advantage is to avoid the segregation of carbides caused by the smelting method to cause mechanical properties and heat treatment deformation.
The heat treatment process of high-speed steel is more complicated and 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. Preheat at 800～850℃ (so as not to cause large thermal stress), then quickly heat to the quenching temperature 1190～1290℃ (different grades have different temperatures in actual use), and then cool by cold or air cooling or inflatable body cooling. All factories use salt furnaces for heating, and vacuum furnaces are now widely used. After quenching, a part (about 30%) of retained austenite is not transformed into martensite because of the internal structure, which affects the performance of high-speed steel. In order to transform the retained austenite and further improve the hardness and wear resistance, generally 2 to 3 times of tempering are required, the tempering temperature is 560℃, and the temperature is kept for 1 hour each time.
Production method: Usually electric furnace is used for production. Powder metallurgy has been used to produce high-speed steel, so that the carbides are evenly distributed on the substrate in the form of extremely fine particles, which improves the service life.
Uses: used to manu
Post time: Jul-08-2021