Hot rolled AISI 5140 steel flat bar production process

1. General overheating: The heating temperature is too high or the heat insulation time is too long under continuous high temperature, resulting in austenite grain passivation treatment, which is called overheating. Thick austenite grains will reduce the ductility of steel, increase the ductility change temperature, and increase the tendency of deformation and cracking during heat treatment. The factors that cause overheating are uncontrollable or incorrect materials on the temperature control surface. Superheat distribution can be quenched, normalized or after multiple high-temperature quenchings, and usually austenization is started from scratch to optimize the grains.

2. Fracture genetic inheritance: Hot rolled AISI 5140 steel flat bar with superheat distribution, after heating and heat treatment from scratch, although the grains of the stainless steel rod can be optimized, thick grain fractures sometimes still occur. There are many theoretical objections to the inheritance of fracture genes. It is generally believed that impurities such as MnS are incorporated into the austenite and accumulated at the crystal interface due to excessive heating temperature. During cooling, these impurities will move along the crystal interface. It precipitates and easily cracks along the thick austenite dislocations when subjected to impact.