Study on the mechanical heterogeneity of electron beam welded thick TC4-DT joints

Tensile properties and microhardness of electron beam welded thick damage-tolerant Ti–6Al–4V joints with the weld cross-section of parallel shaped and taper shaped configurations were examined. Moreover, the mechanical heterogeneity along the weld depth was studied. The results indicate that for both the shaped joints, the weld metal exhibits increased strength and microhardness, while decreased ductility and toughness as compared with the base metal. The mechanical properties of the weld metal are heterogeneous along the weld depth. With the increase of weld depth, the strength and microhardness increase. The weld middle position has smaller mechanical heterogeneity than the weld top and weld root. Moreover, the heterogeneity of parallel shaped welds along the weld depth is lower than that of taper shaped welds. It is also found that the change of mechanical properties such as strength and microhardness has microstructure dependent trend. The mechanical heterogeneity along the weld depth is dependent on the grain size change of β phase and martensite.