Microstructural characterisation of laser beam and gas tungsten arc welded zirconium-2.5Nb

The current study is intended to characterise the complex microstructure that results from autogenous welding of Zr-2.5Nb and its influence on mechanical properties. Laser beam welding (LBW) and gas tungsten arc welding (GTAW) were performed on a 1.5 mm thick samples by applying different combinations of speed and power to vary the heat input. The effect of cooling rate on β-α phase transformation temperature and the resulting microstructure was investigated using a Bahr dilatometer. In addition, mechanical properties were determined by tensile and hardness testing. The base metal microstructure consisted of a fine structure of Zralpha with a small fraction of Nb-beta phase. Both LBW- and GTAWwelded joints displayed similar martensitic microstructures, with the main difference being the weld geometry and strength.This paper was first presented at the AMI Precious Metals 2017 Conference ‘The Precious Metals Development Network’ 17–20 October 2017, Protea Hotel Ranch Resort, Polokwane, South Africa.http://www.saimm.co.za/journal-papersam2018Materials Science and Metallurgical Engineerin