EFEITO DO TEOR DE MANGANÊS NA EVOLUÇÃO MICROESTRUTURAL E NA CINÉTICA DA TRANSFORMAÇÃO BAINÍTICA INCOMPLETA, EM UM AÇO DE ALTO CARBONO.

In this work were studied two alloy steel, shaped hot, by varying the manganese content (1.50% and 1.98%) in order to verify its effect on the morphology and the kinetics of incomplete bainite transformation during austempering, performed at 280 ¢XC for times ranging from 1 minute to 839 h. The temperatures Bs and Ms were determined from simulations, using JMat-Pro® software. It was found the presence of retained austenite in the form of films and blocks, associated with the presence of lath bainitic ferrite, as the main products of the bainitic transformation, in both steels. For alloy B, with higher manganese content, the volume fraction of retained austenite are higher than in the league A, regardless of the time of treatment, due to the effect of manganese to stabilize the austenite. The alloy B in the region of stasis of bainitic reaction showed lower volume fraction of the bainitic ferrite (77%) compared to Alloy A (85%); Additionally, the time to reach stasis in Alloy B (36h) was greater when compared to Alloy A (20h). [ABSTRACT FROM AUTHOR]