Influence of shielding gas on the mechanical properties and visual surface of the welded CP titanium

It is widely known that the welding of commercially pure (CP) titanium and its alloys is difficult to achieve. This is due to the affinity of this metal result the embritlement at high temperatures during welding process. In this study, the tubes of CP titanium SB 338 Grade 2 were welded by using GTAW process in order to conduct a systematic investigation to correlate between the metallurgical reactions during welding on the mechanical properties and the visual color in titanium SB 338 Grade 2 weldments. The parameter used is the shielding gas with varying 3 methods of applied shielding gas to produce 3 types of welded samples. Furthermore the titanium welds samples are examined by tensile, hardness, and visual as well as the gamma-ray radiography test. In addition, SEM and EDS examinations were used to characterize the welds in order to investigate the composition of gases absorbed into the welds. The result shows that the sample produced by using the argon shielding gas with filter, trailing gas, and backing gas with filter has the optimum mechanical properties which have 460 MPa of tensile strength and the hardness of 464 Hv. There was also no crack on the face and root bending test results. The suitable metallic silver color provided on the area of the third sample of welds due to less absorbed of oxygen, nitrogen and carbon into weldments during welding.