THE EFFECT OF MC AND MN STABILIZER ADDITIONS ON THE CREEP-RUPTURE PROPERTIES OF HELIUM IMPLANTED FE-25-PERCENT-NI-15-PERCENT-CR-AUSTENITIC-ALLOY

Helium embrittlement resistance of Fe-25% Ni-15% Cr austenitic alloys with various MX (M = V, Ti, Nb, Zr; X = C, N) stabilizers was compared through post helium implantation creep testing at 923 K. While signif icant deterioration by helium in terms of creep rupture time and elong ation occurred for all materials investigated, the suppression of the deterioration, especially in rupture time, was discerned for the mater ials in which semi-coherent MC (M = Ti, Ti + Nb, V + Ti) particles wer e distributed at high density. The material which contains the incoher ent M,C, as predominant precipitates seems to be less degraded by heli um than those containing the MXs (M = Zr, V; X = C, N), if compared at the same number density of precipitates. Therefore, it is suggested t hat the high density dispersion of incoherent M(23)C(6) as well as sem i-coherent Ti containing MC particles would be beneficial in reducing the detrimental helium influences on mechanical properties.