Improved properties and thermal stability of a titanium-stainless steel solid-state weld with a niobium interlayer

Stainless steel (SS) and titanium alloys can be welded in the solid-state by high speed oblique impact. Here, the effect of a niobium (Nb) interlayer on weld strength and thermal stability is evaluated. Both Ti/SS and Ti/Nb/SS welds were subjected to thermal exposure ranging from 300 °C to 950 °C for 1.5 h. Thermal exposure monotonically decreases the strength and toughness of the Ti/SS pair with a dramatic falloff in strength and change in failure mode from partial pullout failure to full interfacial fracture at 600 °C. With the interlayer, toughness was increased versus baseline up to 700 °C thermal exposure and then intermetallic formation again caused falloff in properties. Guidelines for the production, properties and applications of these classes of welds are provided.