Effect of Stability of y phase on Liiders-like Deformation Behavior of Cold -rolled Fe-Ni-Al-C Alloys

The effect of stability of austenite (gamma) phase on Luders-like deformation behavior of cold-rolled Fe-Ni-Al-C alloys was investigated by digital image electron backscatter diffraction (EBSD) analysis. In this study, cold-rolled Fe-23Ni-5.0Al-0.5C (mass%) alloy (23Ni alloy) and Fe-25Ni-5.0Al-0.5C (mass%) alloy (25Ni alloy) were used. The tensile strength increased and the total elongation decreased with decreasing Ni content. Luders-like deformation after yielding was observed up to a nominal strain of approximately 0.04 for the 23Ni alloy and approximately 1.0 for the 25Ni alloy. The transformation from gamma to martensite (alpha') with a specific crystal orientation relationship was observed during tensile deformation, and it was found that the volume fraction of a' during tensile deformation increased more easily in 23Ni alloy than in 25Ni alloy. In addition, the increment of a' phase in 25Ni alloy was higher during Luders-band propagation than after the band propagation. These results suggested that change of the Luders-like deformation behavior was due to the change in gamma stability.