Effects of the Widmanstatten-like Reversed Austenite on Mechanical Properties in Fe-Ni Alloys

Abstract

The effects of morphology, size and stability of reversed austenite (γ_rev.) on the mechanical properties have been investigated in very low C-high Ni-Steels with particular reference to the Widmanst@/au56/@tten-like γ_rev. (γ_W). The main results are summerized as follows:
(1) Precipitation of γ_W caused increase of tensile strength and yield strength of steels investigated.
(2) Strengthening by the precipitation of relatively stable γ_W was detrimental for the increase of ductility at low temperature, which is the characteristic of low C-Ni-Steels.
(3) When the stability γ_W was relatively low, the high ductility at low temperature was obtained together with remarkable strengthening by γ_W.
(4) Increase of absorbed energy together with some strengthening was observed in the steels in which small amounts of very fine γ_W precipitated.
(5) The marked strengthening by the precipitation of a large amount of γ_W decreased absorbed energy. Precipitation of (γ_LB) along the lath boundaries did not cause remarkable increase of hardness but the decrease of absorbed energy by large amounts of γ_LB was smaller than that by γ_W.