Laser additive manufactured Ti-6Al-4V alloy: Texture analysis

Crystallographic texture analysis has been carried out on direct metal laser sintered Ti-6Al-4V specimens in as sintered and heat treated conditions. The specimens were built in horizontal and vertical directions and subjected to three types of heat treatment cycles (HT-1, HT- 2 and HT- 3). Micro texture analysis was done to study the grain orientation, alpha-beta phase fraction, grain size distribution and grain boundary character distribution. Grains oriented in < 1010 > direction and in-between < 0001 > and < 1010 > directions favours better elongation (11.31-12.6%) and strength (1002-1101 MPa). There is no remarkable effect of a-P fraction on strength and ductility. Below beta transus treatment favours grain refinement in both the orientations. High angle grain boundaries present in HT-2 and HT-3 HB (Horizontal built) specimens drag down the elongation to 8.3 and 4% respectively. Bulk texture measurements carried out on both as-sintered and heat treated specimens reveals weaker texture. HT-2 has a relatively stronger effect on bulk texture evolution with maximum texture intensity range between 12 and 15. As-sintered, HT-2 and HT-3 specimens reveal similar texture components (A and D) whereas HT-1 HB specimen reveal two different texture components (B and E). Residual stress measurement indicates that compressive stress tensor has significant effect on % elongation, whereas it is not so with tensile stress tensor. All together, the effect of crystallographic texture and residual stress on the mechanical properties of as-sintered and heat treated Ti-6Al-4Valloy specimens are discussed.