TWI Industrial Member Report Summary 115/1980
By M F Gittos, M H Scott and R J K Nicholson
Autogenous TIG welds were made in 1.5mm thick commercially pure Ti sheet using Ar shielding gas which was progressively contaminated with O or air. The welds were examined visually for surface colour and by an ESCA technique, the welds analysed for 0 and N pick-up and tensile and hardness tests carried out on selected welds. Surface discoloration was found to be primarily controlled by conditions under the trailing shield rather than the torch nozzle and to be a poor indicator of the level of contamination, except when this was gross. Contamination of the electrode tip appeared to be at least as sensitive.