Investigation of ultrasonic indications in Ti alloy (Ti6Al4V) hot formed hemisphere

Pressure vessels of titanium alloy (Ti6Al4V) are made through electron beam welding of hot formed hemispheres. During ultrasonic inspection of a batch of hot formed and machined hemispheres, ultrasonic indications beyond acceptable levels have been observed while inspecting as per AMS 2630B for class A1, whereas input material (hot rolled and annealed plate) has been qualified to the level of class A1. This paper presents the detailed investigation carried out to study the problem and to bring out the reasons behind the same. The authors attempted to correlate the microstructural features of this (α–β) alloy in hot formed and annealed condition with the recorded ultrasonic indications.