In situ analysis of cryogenic strain of AISI 316L stainless steel using synchrotron radiation

AISI 316L austenitic stainless steel was tested by simultaneous uniaxial tensile tests and X-ray diffraction measurements at room and cryogenic temperatures. The decrease in temperature reduced the stacking fault energy, which increase the rate of the martensitic transformation. This led to an intensive formation of martensite during the early stage of deformation, and consequently induced a discontinuous yielding. The tensile strength at cryogenic temperature was higher than that obtained at room temperature, while the steel ductility did not change significantly. This behavior could be associated with the Transformation Induced Plasticity (TRIP) effect since the formation of alpha' martensite increased the work hardening rate. In addition, the threshold strain for the onset of discontinuous yielding seems to be related to the lattice microstrain of austenite and the intensive formation of martensite.