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

• Published in: Materials chemistry and physics 2019-03, Vol.226, p.272-278
• Main Author: Chandramohan, P.
• Format: Article
• Language: English
• Subjects: Beta phase; Compressive properties; Crystallography; EBSD; Elongation; Grain; Grain boundaries; Grain orientation; Grain refinement; Grain size distribution; Heat treatment; Laser sintering; Mathematical analysis; Mechanical properties; ODF; Residual stress; Stress measurement; Tensile stress; Tensors; Texture; Titanium base alloys
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2019.01.035

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, α-β phase fraction, grain size distribution and grain boundary character distribution. Grains oriented in direction and in-between and directions favours better elongation (11.31–12.6%) and strength (1002–1101 MPa). There is no remarkable effect of α-β 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. [Display omitted] •There is no remarkable effect of α-β fraction on strength and ductility.•Below β-transus treatment refine grains in horizontal and vertical orientations.•Bulk texture measurements carried out reveals weaker texture.•Above β-transus treated horizontal built specimens forms new texture components.•Compressive stress tensor in residual stress favours better % elongation.