Study of the Linear Friction Welding process of dissimilar Ti-6Al-4V – stainless steel joints

Linear friction welding (LFW) is an innovative joining method that can be used to obtain high strength joints between dissimilar materials. A key factor that influences the joints performances are the intermetallic compounds that could be formed during the welding process. These intermetallics are brittle and could compromise the mechanical performances of the joint. This paper deals with the analysis of the LFW process of dissimilar titanium-stainless steel joints. Two different types of joints were studied: AISI 304 – Ti6Al4V and AISI 316 Ti6Al4V. Particular attention was paid to characterizing the intermetallic compounds using Scanning electron microscopy, Electron Probe microanalysis and X-ray diffractometry. Zones with different microstructure were observed. Due to the diffusive phenomena occurring during the welding Kirkendall effect and several intermetallics were observed. Moreover it was found that the joint with AISI 316 formed brittle intermetallic compounds that lead to the crack formation close to the weld line.