Deformation behavior of lean duplex stainless steels with strain induced martensitic transformation: Role of deformation mechanisms, alloy chemistry and predeformation

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

“…Regarding to bcc phase, the peak (110)α has also been decreased with rolling reduction, but the major decreasing was on as-received sample (AR) after tensile test. Peaks (200)α and (211)α also increased after tensile test in all samples, which could suggest the strain-induced martensite transformation and texture strengthen of the material [1,8,9].…”

“…A slight increase in bcc phases (ferrite and α¢-martensite) volume fraction was observed with increasing deformation during cold rolling. The main variation of austenite and bcc phases was observed on the AR sample after tensile test, which is another evidence of the TRIP effect [8][9][10]. Sandim et al [22] have found a α'-martensite saturation, 25%Vv, on heavy cold-rolled (80%) samples of the same steel, after homogenizing annealing at 1080 °C for 30 s. This amount corresponds to the difference between austenite found on AR and AR-T samples, which is 25%Vv.…”

“…The microstructure of the samples after tensile test is shown in Figure 2. The microstructures are composed by a continuous matrix of ferrite (α), darker on the micrograph, alternating with lenticular-shaped austenite (γ), typical of rolled DSS [6,[8][9][10]. Brighter phase with needles morphology inside γ grains, like martensite, appears, in all conditions.…”

“…The plastic deformation of ferrite is mainly controlled by dislocations slip, due to their high stack fault energy (SFE), whereas austenite has different modes of deformation, such as dislocations slip, deformation twins and strain induced martensite transformation [4,[8][9][10]. Other authors report the single-walled Taylor lattice domain boundaries (DB), double-walled microbands (MB) action in synergy with mechanical twins [11].…”

Macro and micro mechanical in-situ characterization using synchrotron diffraction of architectured micro-composite duplex stainless steels

“…The high strength/elongation and the deviation from the law of mixture were found to be the most important features of conventional DSS. These characteristics are usually attributed, in the literature, to several factors: i) differences in plastic behavior between the ferritic and austenitic phase [6] [7]; ii) residual stress and texture effects [8]- [11]; iii) Transformation Induced Plasticity (TRIP) [12], [13]; iv) other microstructural effects such as the formation of precipitations, phases' grain size or the morphology [14]- [16].…”