Influence of Filler Metal on the Microstructure and Mechanical Properties of 316Ti–15-5 PH Stainless Steel Weld Joints

Dissimilar metal weld joints of austenitic stainless steel (SS) 316Ti and 15-5PH stainless steel were produced through gas tungsten arc welding (GTAW) using two different grades of filler wire, viz., ER316L (austenitic grade) and ER630 (PH grade). Microstructure evaluation and mechanical properties of weldments were carried out to derive the best filler wire combination. The results showed that the joints prepared with ER316L filler wire possess austenite-ferrite dendritic weld structure and has lower strength than the 316Ti base metal. The weld joint ER630 filler wire displayed superior mechanical properties compared to the weld with ER316L filler wire. The use of ER630 filler wire led to the formation of martensitic structure in the weld, making the weld stronger than the austenitic 316Ti base metal. Thus, failure occurred in the base metal 316Ti during testing instead of weld. However, the fractographic examination of tensile tested specimens revealed presence of dimples in both cases, indicating that the failure mode was ductile. Based on this study, it is recommended to use ER630 filler wire to weld 316Ti–15-5PH for obtaining stronger weld joints.