Effect of interpass temperature on in-situ alloying and additive manufacturing of titanium aluminides using gas tungsten arc welding

This study examines the influence of different interpass temperatures on in-situ alloyed and additively manufactured γ-TiAl alloy. The microstructure, chemical composition, phase constitution and microhardness of all the test components were respectively examined by using light microscopy, SEM-EDS, X-ray diffraction and a Duromain 70 Hardness Tester. No appreciable changes in microstructure and composition were found as interpass temperature was changed. However, as the interpass temperature was increased from 100 °C to 400 °C, a decrease of α2 phase fraction was observed due to the lower cooling rate. Consequently, the microhardness value also decreased. A further increase of interpass temperature to 500 °C produced only minor reductions in the brittle α2 phase fraction and the microhardness value. In view of these results, a suitable interpass temperature was found for producing crack-free components.