Microstructure Control in Welds of the Ti-6A1-6V-2Sn Alloy
An investigation was conducted to determine the response of Ti-6A1-6V-2Sn weldments to subsequent heat treatments. The as-welded and post heat treated microstructures were studied using bead-on-plate welds as well as with Gleeble blanks, thermally treated to synthesize the HAZ regions of titanium alloy weldments. Fracture toughness and tensile tests were conducted on specimens from these blanks, and the results were correlated with the microstructural features. Although certain heat treatments recommended for wrought material did not result in the same microstructure or property responses when applied to the HAZ, present structure/ property relationships were used to explain the results. It was noted that the coarsening of alpha plates and the formation of grain boundary alpha appeared to be the microstructural changes which raised the fracture toughness in the HAZ. As these changes proceeded to a very great extent, tensile ductility was sacrificed somewhat for further gains in fracture toughness.
KeywordsCool Rate Fracture Toughness Base Metal Fusion Zone Welding Speed
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