Effect of composition, microstructure, and texture on stress-corrosion cracking in Ti-61-4V sheet

Ti-6Al-4V stress-corrosion cracking data, K_SCC, mechanical properties data, and metal-lurgical characteristics including variations in composition, microstructure, and basal plane crystallographic texture were correlated using linear regression analysis technique. The test data, representing 46 commercial heats of duplex-annealed material, exhibited variations in K_SCC values from approximately 20 to over 100 ksi-in.^1/2 (approximately 22 to over 110 MPa-m^1/2). Regression analyses resulted in several equations that showed good correlations of K_SCC values to metallurgical parameters. The regression analysis equations showed the most significant metallurgical parame-ters controlling K_SCC to be oxygen content, texture, and alpha phase ordering (alpha phase ordering was found to be promoted by oxygen). Relatively high oxygen contents, strong textures, and high degrees of ordering were responsible for low values of K_SCC.