TECHNICAL PAPER TP 2867 Role of Material Thickness on Tensile Properties of Ti6Al4V Welds M. Gopalakrishna Pillai • R. K. Gupta • Bhanu Pant • P. S. Sreejith Received: 16 June 2014 / Accepted: 28 October 2014 Ó The Indian Institute of Metals - IIM 2014 Abstract Ti6Al4V being a workhorse material for aero- space systems with wide range of applications, it is welded in a large variety of thickness depending on the design requirements. Two types of welding processes are usually followed, namely electron beam welding (EBW) and gas tungsten arc welding (GTAW). Weld parameters for Ti6Al4V alloy sheets and plates through EBW and GTAW have been established for different thickness (2, 8, 12 and 21 mm) and the weld properties were evaluated. Analysis of data revealed decrease in mechanical properties of the weld for a specific thickness compared to parent metal. Weld efficiency of GTA weld was found to be lower compared to EBW. Similarly, effect of thickness on weld properties was found to be more pronounced in the case of GTA welds. The effect of thickness on energy input and mechanical properties is also discussed in relation to the process adapted highlighting the values of 12 and 21 mm thick plates. Keywords Ti6Al4V  EBW  GTAW  Material thickness 1 Introduction Titanium with a melting point of 1,668 °C and density of 4.5 gm/cc is very attractive in terms of strength to weight ratio (specific strength). Titanium and its alloys offer excellent mechanical properties, undergo very little creep and are structurally stable up to a service temperature of 550 °C. They also offer outstanding cryogenic properties, very good corrosion resistance, good fatigue strength, good fracture toughness and a high rigidity to weight ratio. This unique combination of properties makes titanium and its alloys an important material for aerospace application [1]. Ti6Al4V a workhorse material is an alpha–beta alloy containing 6 % Al (a stabilizer) and 4 % V (b stabilizer). It has good weldability. Its tensile properties and fracture toughness in annealed condition attracts designers to apply the alloy in various systems [2]. Electron beam welding (EBW) and gas Tungsten Arc welding (GTAW) processes are generally followed for welding of aerospace systems. In EBW, weld contamination is reduced to a great extent as the welding is carried out in a high vacuum environ- ment. Near parent metal weld strength can be achieved in this energy efficient process. Deep penetration with narrow fusion zone, low distortion, narrow access capability, controlled repeatability, faster rate of welding are some of the advantages of EBW [1, 3, 4]. In view of the advantages like contamination-free weld, deep penetration character- istic and low energy input, EBW is the most suitable process for titanium welding. However, there are many areas where EBW is difficult to adopt due to either requirements of large size welding machine for big com- ponents or due to different weld configurations. In such a scenario GTAW becomes useful. Sufficient amount of lit- erature is available on the welding study of EBW and GTAW. However, effect of sheet/plate thicknesses on the M. Gopalakrishna Pillai BrahMos Aerospace, Trivandrum, India R. K. Gupta (&)  B. Pant Materials and Mechanical Entity, Vikram Sarabhai Space Centre, Trivandrum, India e-mail: rkgupta.isro@gmail.com; rohitkumar_gupta@vssc.gov.in P. S. Sreejith Institute of Human Resource Development, Trivandrum, India 123 Trans Indian Inst Met DOI 10.1007/s12666-014-0471-y