FABRICATION STRAIN-RATE STRESS-CORROSION PROPERTY CORRELATIONS OF THERMOMECHANICALLY TREATED 15CR-15NI-2-CENTER-DOT-2MO TITANIUM-MODIFIED AUSTENITIC STAINLESS-STEEL

A 15Cr-15Ni-2.2Mo titanium modified austenitic stainless steel was the rmomechanically worked to a strain of 30% in a single stage at tempera tures between 873 and 1473 K and at strain rates of 0.15, 1.0, and 100 s(-1). These strain rates were obtained by working the alloy in a hyd raulic press, a rolling mill, and a forge hammer, respectively. At all strain rates, the yield strength (YS) increased while ductility and s tress corrosion cracking (SCC) resistance significantly decreased on t hermomechanically working the solution annealed allay at temperatures below 1173 K. Thereafter the YS decreased and ductility along with SCC resistance inn eased substantially towards values for the solution an nealed alloy on thermomechanical treatment at and above 1273 K. The hi ghest ductility was obtained on working the alloy at a strain rate of less than 1.0 s(-1). However; the best SCC resistance was obtained on working the material at the highest strain rate of 100 s(-1). The impr ovement in SCC resistance has been attributed to the finer grain size obtained on working the alloy at higher strain rates. Fractographic ex amination indicated failure by transgranular SCC. The size of the fan shaped patterns increased with increasing temperature of working, and decreased with increasing strain rate of fabrication. MST/3913.