Friction welding of pure titanium and pure nickel

Abstract

The joint tensile strength and metallurgical properties of a friction welded joint of commercially pure Ti and pure Ni has been investigated in as welded and post-weld heat treated conditions. While friction pressure did not significantly impinge on joint tensile strength, joint tensile strength was affected by friction time. A 1–1·5 μm thick interlayer is essential to join pure Ti and pure Ni using friction welding. A maximum joint tensile strength of 450 MPa was achieved and the joint fractured in the Ti original (not heat affected zone) substrate, i.e. the joint efficiency was approximately 112% relative to Ti substrate and 94·5% relative to Ni substrate. The joint tensile strength abruptly decreased as heating temperature was increased to 873 K and/or the Larson-Miller parameter was increased to approximately 19–20 × 10³. The joint tensile strength rapidly decreased with increasing interlayer thickness up to approximately 10 μm, and then remained constant for further increase in interlayer thickness. Four layers occurred at the interface of joints heated to more than 873 K, namely Ti₂Ni, TiNi, TiNi₂, TiNi₃. The fracture of heated joints propagated mainly in the Ti₂Ni layer and/or at the interface between the TiNi and TiNi₃ layers.

Keywords:

• FRICTION WELDING
• TITANIUM
• NICKEL
• INTERFACE
• INTERLAYER
• INTERMETALLIC COMPOUND