Estudo de elevada taxa de resfriamento após recozimento intercrítico aliado com redução a frio e recozimento subcrítico para viabilizar a esferoidização do aço SAE 52100

Abstract

Considering the high cost associated with the spheroidization heat treatment of bearing steels, it is necessary to study alternatives to decrease the annealing heat treatment time. This work aimed to develop a new manufacturing route in order to obtain a completely spheroidized microstructure. The microstructure and mechanical properties of the steel were evaluated after intercritical annealing with higher cooling rate than the conventional one, followed by cold deformation with different reductions in area, and subcritical annealings with different soaking times. It has been observed that the route considering the intercritical annealing with cooling rate 8.6 times higher than the conventional one, followed by a high cold reduction and subcritical annealing for 1 hour turns feasible the complete spheroidization of SAE 52100 steel. For low cold reductions, even with subcritical annealing during 3 hours, the samples showed lamellar carbides. Regarding the mechanical properties, for the same cold reduction, it was not identified significative difference for yield strength, tensile strength and hardness by increasing the soaking time during subcritical annealing. Nevertheless, the yield strength for the samples in higher reduction was bigger than the samples in lower reductions.