Hardening Characteristics of Ti-6Al-2Sn-4Zr-6Mo Alloy.
Abstract:
Research was conducted to develop heat treatments for Ti-6Al-2Sn-4Zr-6Mo alloy which have potential for minimizing microstructural and mechanical property variations in geometrically nonuniform components. Microstructure was found to be strongly dependent upon both the solution heat treating temperature and the cooling rate solution heat treatments using two steps at differing temperatures appeared to minimize these differences. Certain heat treating conditions formed subgrain networks, called SERB, in the microstructure. Two maxima appeared to exist in the aging response curve for slowly cooled specimens aged at 1100 F a potential mechanism for this phenomena was postulated. Fracture toughness was found to be inversely proportional to the amount of primary alpha phase present when relatively coarse acicular alpha exists. The fracture toughness for thick sections increased as the spread in the value of TUS-TYS increased. The best combination of mechanical properties obtained in the short transverse direction at the center of a 3-inch diameter, simulated, air-cooled component was tensile yield strength, 158 ksi ultimate tensile strength, 167 ksi fracture toughness, 36 ksisquare root ofin and reduction in area, 37. These properties were obtained using a two-step solution heat treatment consisting of 1700 F1hrSC 1550 F1hrSC aging was 8 hours at 1100 F. Author