| Fe-28%Ni alloy was subjected to the repeated thermal cycling for the γ⇔α`, their effects on the transformation temperatures and tensile properties were investigated. The Ms temperature was singnificantly lowered with increasing the numbers of cyclic heat treatments, particularly at the first cycle. On the other hand, the Md temperature was slightly raised. In the range between Ms and Md temperature, the elongation peak was appeared and decreased by cyclic heat treatments. As the test temperature was remarkably lowered in this range, the yield strength of the cyclic heat-treated specimens increased first and then decreased but the ultimate tensile strength was continuously increased. The increment of the yield strength caused by cyclic heat treatments was large, but in case of the ultimate tensile strength was not so. |
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