Influence of Agitation Rate on Residual Stresses and Distortion on Quenched AISI 5160 Steel

The rapid cooling in quenching heat treatment results in thermal stresses due to high thermal gradients. Thermal residual stresses can potentially affect the martensitic transformation as well the distortions. Distortion is one of the main problems of manufacturing and heat treatment is the main cause of this phenomena. It is known, that the quenchant agitation is a parameter that influences the cooling rates and consequently the residual stresses and distortions. In this way this work proposes to quench an AISI 5160 steel in three different levels of agitation, a conventional mineral oil at the same temperature. Cooling curves analysis, finite element simulation and metallographic observation support the obtained conclusions. It is found that a moderate agitation rate produces better results in terms of distortion and thermal residual stresses.