Explanation

A heat treatment process in which hypo-eutectoid steel is heated to the temperature between Au, and a part of ferrite is retained after holding, and then rapidly cooled. It can obtain a dual phase structure of martensite and ferrite, with good uniform plasticity and ductility, and is widely used in the production of dual phase steel. As for mechanical parts, low heating temperature can refine austenite grains, reduce segregation of harmful impurities such as phosphorus, improve toughness of steel and reduce temper brittleness. subthermal quenching can be heated to above Au and completely austenitized before cooling into the subtemperature zone for proper heat preservation before quenching, or it can be heated from low temperature to the subtemperature zone for proper heat preservation before quenching. The size of the first eutectoid ferrite precipitated along the austenite grain boundary is relatively large in the former, while the undissolved ferrite obtained in the latter is fine and evenly distributed, so the toughening effect of the latter is better.

Classification