Avaliação da cinética de precipitação de fase sigma em aço inoxidável duplex SAF 2205.

Abstract

Duplex stainless steels are high alloy steels which have high Cr-Ni-Mo content. their characteristics are excellent corrosion resistance and superior mechanical resistance to austenitic stainless steels. They have a supersaturated Ferritic matrix of Cr and Mo, and when exposed to high temperatures can form intermetallic phases capable of compromising their mechanical and physico-chemical properties, hindering the performance of the material in their application. The present study aims to evaluate the occurrence of precipitation of intermetallic sigma phase that is rich in Cr and Mo in SAF 2205 steel at temperatures of 650, 750 and 900 ° C several times up to 10 hours. The formation of this phase can lead to the impoverishment of Cr and Mo in the ferritic matrix and compromise the corrosion resistance of the material. Performing the analysis of preciptation and of growth of the sigma phase and verifying if the formation of the kinetics phase follow the equation proposed by Johnson-Mehl-Avrami (JMA).