Work hardening analysis in a lean duplex stainless Steel 2304 after low deformation by cold rolling

Abstract

The deformation mechanism of lean duplex stainless steel (LDSS) is overly complex not only by their dual phase microstructure, but also due to metastable austenite, which can deform by different mechanisms and transform to martensite by strain. The purpose of this study was to investigate the mechanisms of deformation by tensile test on low deformed cold-rolled samples (4%-22%) of a 2304 LDSS. The microstructure was analyzed by X-ray diffraction, optical microscopy, electron backscattered diffraction and transmission electron microscopy. It was observed the formation of mechanical twinning, ε-martensite, and α'-martensite which evidenced the TRIP effect. The strain hardening rate was calculated and analyzed by Holomon and Crussard-Jaoul modeling together with instantaneous strain hardening exponent, and three operating mechanisms were observed: twinning, dislocations slipping, and strain induced martensite formation (SIM). Brass texture had compromised SIM transformation. The fractography analysis of tensile specimens showed quasi-cleavage occurrence, and dimples formation for this range of pre-deformation.

Influence of Quenching and Partitioning on the Mechanical Properties of Low‐Silicon 33MnCrB5 Boron Steel

“…The transformation starts from the less stable austenite particles and moves to the more stable ones for increasing strain. [ 37,48 ] Strain‐induced transformation indeed slows down the decrease of the hardening coefficient as undeformed FM, featured by a high hardening coefficient, is progressively formed [ 49 ] : the decrease of the hardening coefficient becomes thus smooth, and necking is delayed. The trend observed is similar to the one observed by De Moor et al [ 41 ] and, with a different representation, Finfrock et al [ 45 ] for QP steels.…”