Interfacial Microstructures and Characterization of the Titanium-Stainless Steel Friction Welds Using Interlayer Technique

The joints of dissimilar metals and alloys are increasing demand as essential parts of aerospace, nuclear and cryogenic applications. One of the greatest challenges for design engineers is to develop and implement fast and cost-effective industrial procedures to join titanium with stainless steel and aluminum. Regardless of the welding conditions, such high specific properties of the metal combinations cannot be fusion welded in conventional method, because of the formation of highly brittle intermetallic compounds in the fusion zone. However, solid-state joining processes, friction-welding process contemplated to offer the highest potential for successful joining of bimetallic components. The friction welding techniques are highly efficient and it has the advantage of far greater weldability and reduces the risk of interfacial reaction. In the present investigation, microstructure formation at the interfaces of friction welds between titanium and stainless steel with and without interlayer are discussed. The formation of fragile intermetallic compounds like Fe-Ti and Cr-Ti are completely avoided between the titanium and stainless steel by introducing of interlayer material. The interlayer material successfully controlled the undesirable compounds from the weld interface and developed a new weld interface. The new microstructure formation at weld interface enhanced the final properties of the titanium to stainless friction welds.