Influência da taxa de deformação e da temperatura na ductilidade a quente do aço inoxidável duplex UNS S32304

Abstract

Duplex stainless steels (DSS) have two ductile phases, i.e. ferrite and austenite, with a balance around 50% of each phase. The main advantage in comparison with other austenitic and ferrite stainless steels is the excellent combination of high strength and corrosion resistance together with good formability and weldability. Unfortunately, DSS present in general a poor hot workability and as a consequence, surface defects as edge cracks and slivers are always susceptible, what became complex the fabrication process of the DSS during the stage of hot rolling. Hot torsion tests were subjected in this study to evaluate the hot ductility of DSS UNS S32304 at a temperature range of 1000 to 1200°C and strain rate from 0.1 to 5s-1. The low ductility was atributed to the crack fomation at the austenite and ferrite interface and is mainly related to the diference in mechanical behavior between austenite and ferrite fases during deformation. The increase in temperature resulted in higher ductility. The increase in the deformation rate resulted in lower ductility.