Spark Plasma Welding of Austenitic Stainless Steel AISI 304L to Commercially Pure Titanium

In modern fast-breeder nuclear power plants, on-site fusion welding of austenitic stainless steel AISI 304L and commercially pure titanium pipes is called for. The application imposes stringent requirements on these joints in terms of tensile strength, bend ductility, and corrosion resistance in boiling nitric acid. However, fusion welding of stainless steel to titanium directly is a near impossibility because of inevitable brittle intermetallic formation between iron and titanium and, consequently, serious weld cracking problem. All things considered, the best way to realize these joints is to make use of solid-state welded stainless steel/titanium (SS/Ti) dissimilar pipe joining inserts or adaptors. Towards this end, many solid-state welding techniques such as diffusion bonding, friction welding, and explosive welding have been tried in past, but without much success. In the current study, solid-state welding of SS rods to Ti rods was attempted in spark plasma sintering equipment. The potential of this new process, termed spark plasma welding, for dissimilar metal welding are discussed.