A study on the effect of welding parameters and heat input rates on titanium weld's grain size

Fine grains help to improve the mechanical properties of the weld such as ductility and fracture toughness. In most titanium welding applications, beta grain size is determined principally by the weld energy input, with a higher energy input promoting a courser grain size. The beta grain size may be reduced somewhat by altering the welding parameters. This paper presents a study on the effect of welding parameters (current and speed) and corresponding heat input rate and cooling rate on the grain size of a titanium α/β alloy. It was found that with smaller heat input rates, the effect of welding speed in determining the grain size was found more significant than that of welding current. It was also found that with lower cooling rate, the grain size was larger. At the HAZ, there is a general decrease of grain size when moving towards the parent metal.