Thermomechanical working of Astroloy

Astroloy was warm rolled at temperatures between 1450° and 1800°F, and directly aged in the temperature range from 1300° to 1600°F. Room temperature tensile strengths of 250 ksi and 0.2 pct yield strengths of 200 ksi were obtained by subjecting the alloy to a 20 pct reduction at 1550°F followed directly by an 8-hr aging treatment at 1600°F. The tensile properties of the thermomechanically treated material remained superior to those of normally heat treated astroloy up to test temperatures of 1800°F. The warm working primarily served to refine both the γ′ precipitate and the grain boundary carbides. Preliminary stress rupture tests have indicated that the resulting thermomechanically treated material is markedly inferior to the normally heat treated alloy when compared on the basis of long time properties.