Structure and mechanical properties of TC4-DT titanium alloy by laser additive joining br

TC4-DT titanium alloy forgings with X-type groove were joined by laser additive joining technology. OM and SEM were used to characterize the macro and micro morphology of TC4-DT titanium alloy base metal, heat affected zone and joining zone. The microhardness of the three regions was measured by Vickers hardness tester. The tensile and impact tests of different samples were carried out at room temperature with universal testing machine and pendulum impactor. The results show that there is a dense metallurgical bond between the joining zone and the base metal. Distribution of microhardness from the base metal to the joining zone shows an increasing trend. The strength of TC4-DT alloy increases first and then decreases with the decrease of the proportion of the joining zone in tensile specimen, while the plasticity decreases. The impact toughness au is above 55 J/cm(2). The position of U-shaped notch opening has a great effect on the impact toughness of the joining zone but not the bond zone.