Texture evolution during strain-induced martensitic phase transformation in 304L stainless steel at a cryogenic temperature

摘要

The strain-induced martensitic phase transformation during quasi-static uniaxial compression testing of a 304L stainless steel was investigated at 300 and 203 K using time-of-flight neutron diffraction to study the evolution of transformation texture. A number of specimens were precompressed to different strain levels at 300 and 203 K and the texture was investigated. At 203 K, the newly formed martensites are bcc and hcp phases and the texture analysis shows that the martensites are highly textured due to the grain-orientation-dependent phase transformation. The bcc {100} planes are mostly oriented with their plane-normal parallel to the loading direction at the beginning of the phase transformation and this texture is weakened during the subsequent compressive deformation. In the case of fcc to hcp transformation, it is less dependent on the grain orientation, although the fcc grains with {111} plane-normal at an angle close to 40 deg to the loading direction transform easier and the {0001} plane-normal of the newly formed hcp phase tends to rotate toward the loading direction during the texture evolution. The final texture of bcc and hcp martensites is the result of the interaction between deformation texture and transformation texture.