Carbide morphology in p/m IN-792

Adequate tensile and smooth stress rupture properties were achieved by heat treating p/m IN-792 to produce serrated grain boundaries pinned with a globular M23C6 precipitate. A notch-strengthened condition with Kt = 3.5 at 1400‡F (1033 K)/90 ksi (620 MN/m2) was achieved when the material was heat treated to produce a grain size larger than about 76 Μm (ASTM G.S. #6). To obtain this grain size using realistic solution time-temperature heat treatments, the carbon content of the IN-792 should be maintained below 0.1 pct and preferably about 0.04 pct.