Quantitative deformation measurements and analysis of the ferrite-austenite banded structure in a 2205 duplex stainless steel at 250 °C

The deformation process of the microstructure in 2205 duplex stainless steel (DSS) under thermo-mechanical coupling at 250 degrees C was investigated using digital image correlation (DIC). A thermal tension test of duplex stainless steel (2205DSS) with a banded structure was carried out to observe the initial deformation of the microstructure. It was found that inhomogeneous strain fields occurred primarily in austenite. The maximum normal strain in austenite was almost positive, while that in ferrite was almost negative. In addition, a thermal cyclic-loading test was conducted, and the strain field was characterized by e(11). Strain heterogeneities were induced after 400 cycles, which spread within the austenite and at the phase boundaries with the load increasing. The high tensile-strain regions were always located adjacent to regions of intense compressive strain. Based on the strain matrix sum vs. cycle number, we found that hardening occurred in the early cycles followed by softening.