Análise microestrutural do aço Dual Phase tratado por Têmpera e Partição

Abstract

In this work the microstructure generated in the Dual Phase steel by the Quench and Partition (T & P) treatment was evaluated. The heat treatment consists of heating the material at 740 ° C for a soaking time of 1h in the region considered to be intercritical, followed by quenching in brine and water at temperatures of 100 ° C and 200 ° C respectively, intermediate at Ms and Mf temperatures, in an isotherm (partition treatment) of 30 minutes.Optical microscopy (MO),scanning electron (SEM) and backscattered electron diffraction (EBSD) techniques were used for the microstructural characterization of the obtained material. For the characterizations via MO and MEV, Le Pera and Nital 5% were used to contrast phase and constituent, while in the EBSD the maps and quality index (IQ) were used, noting ferrite formation and complex microstructure (martensite, martensite, and possibly bainite) in the microstructure of the steel.On other hand, the quantification of phases were analyzed by histograms of IQD of the EBSD in the software Esprit 2.1, observing the presence of the fraction of the ferritic phase and the constituent present. After, hardness and microhardness test was performed to evaluate the resistance of regions. The results indicate that the MO, MEV-FEG and EBSD techniques contributed to the microstructural understanding, especially the MEV-FEG analysis, allowing the observation of more details, such as chemical composition and topography.