Efeito do tratamento térmico na proporção de fases e nas propriedades mecânicas dos aços inoxidáveis duplex uns s31803 e uns s32304

The duplex stainless steels (DSS) has an austenite-ferrite microstructure composed by about 50% of each phase, such characteristic gives to the DSS high corrosion resistance under strain.Those steels have significant addition of alloy elements, which are responsible for the appropriate phase balance and also ensure the desirable properties.Other important parameter for the correct phase balance is the thermomechanical processing.Therefore, this study evaluated the influence of different temperatures of heat treatment in the phase fraction (ferrite and austenite) and the mechanical properties of UNS S32304 and UNS S31803.The annealing were performed at five temperatures with fixed soaking time and followed by rapid cooling.The quantification of primary phases were performed through optical microscopy (OM) and the mechanical properties were evaluated in an uniaxial tensile test.The measurements of primary phase fraction indicate that with increasing annealing temperature there is an increase in ferrite fraction and the temperature where microstructure is more close to 50% ferrite and 50% austenite was around 1020°C in both DSS studied.Furthermore, it was observed that with increasing temperature and thus the ferrite fraction, there was a reduction in tensile strength in both DSS of this study.