Obtenção de aços fundidos de elevada resistência mecânica, boa tenacidade e resistência ao desgaste

Abstract

The research lines of high mechanical strength steels generally involve shaped materials, although the cast steels may stand out due to the possibility of obtaining components of complex geometries, varied dimensions with practically definitive shapes and lower cost. This work proposes the study of cast steel, without mechanical processing that has good mechanical characteristics. The chemical composition selected for this work consisted of a low carbon steel and high silicon that was subjected to isothermal treatment at temperatures of 300°C and 400°C, ranging from 1 to 20hours. The silicon content (2.19%) was defined in order to inhibit the formation of carbides, favoring the carbon enrichment of austenite during the formation of the carbide-free acicular ferrite constituent and increasing the retained austenite fraction. Austenite treatment at 400°C for 2hours resulted in a cast steel with lower mechanical strength and lower ductility than the isothermal treatment at 300°C for 2hours. This heat treatment produced a more refined microstructure that presented higher toughness and greater mechanical resistance and ductility. These results indicate that these heat treatments are promising for increased wear resistance since it has secured properties that are critical for fracture mechanisms not to predominate in sliding and abrasive wear. In particular, the treatment below the martensite start temperature (Ms) temperature of the steel.