Fe-Ni 합금에서 래쓰 마르텐사이트와 렌즈상 마르텐사이트의 반복변태사이클(α' ↔ γ')에 따른 미세조직과 기계적 성질

Effect of Transformation Cycles(α' ↔ γ')on Microstructures and Mechanical Properties of Lath and Lenticular Martensites in Fe-Ni Alloys

The influence of transformation cycles (${\alpha}^{\prime}{\leftrightarrow}{\gamma}^{\prime}$) on the microstructure and mechanical properties of lath and lenticular martensites has been studied in Fe-Ni alloys. The width of lath in Fe-15%Ni alloy decreased with increasing the number of transformation cycles, while no appreciable change in dislocation density inside the lath was observed. In case of Fe-31%Ni alloy, a number of dislocations were additionally introduced into the martensite plate after the transformation cycling. Tensile strength and Vickers hardness of lath martensite decreased with the increase in number of transformation cycles, whereas those of lenticular martensite increased up to 1 cycle and then remained constant. Elongation of two alloys was deteriorated after 1 transformation cycling, corresponding to the tensile strength. But the decrement of elongation in Fe-31%Ni alloy was smaller than that in Fe-15%Ni alloy.