1. General overheating: heating temperature is too high or at high temperature holding time is too long, cause the austenitic grain coarsening called overheating. The coarse austenite grain can reduce steel strong toughness and brittle transition temperature, the increase of quenching deformation and cracking tendency. And the cause of overheating temperature instrument is out of control or mixing (often happen to don't understand the process). Overheating by annealing, normalizing or many times after high temperature tempering, in normal circumstances to austenite grain refinement.

2. Fracture overheating of steel, reheating after quenching, austenitic grain refinement can make, but sometimes still appear rough granular fracture. Over genetic theory of fracture is more, it is generally believed by the heating temperature is too high and make the sundries such as MnS into austenite and enrichment for the interface, and cooling these inclusions can precipitate along crystal interface, easy when rough along austenite grain boundary faults.

3. Bulky organization genetic: there is gross martensite, bainite and westergren steel to austenite of body tissue, with slow heating to conventional quenching temperature, even lower, the austenitic grain size is still a massive, this phenomenon is called genetic organization. Can be used to eliminate the bulky organization of hereditary, intermediate annealing or high temperature tempering treatment many times.