Friction Welding of Type 304 Stainless Steel to CP Titanium Using Nickel Interlayer

Abstract

Dissimilar metal joints of stainless steel to titanium find extensive industrial applications especially in the nuclear industry. However, it is well known that fusion welding of stainless steel to titanium is difficult because of the formation of brittle intermetallic compounds and the associated problems. To avoid this, welding processes or techniques with high reliability and productivity for these dissimilar materials are demanded. In the present work, joints comprising of 304 stainless steel and commercially pure titanium were produced by friction welding using nickel as interlayer. Investigation on the mechanical properties of the joints shows the occurrence of highest hardness value at the interface of titanium and nickel interlayer. X-ray diffraction studies confirmed the presence of various types of intermetallic compounds at the interface of the welded joint. The tensile strength of the joint varies with the thickness of nickel interlayer used. Joints having maximum strength equals to 72% of that of titanium base metal could be produced. In all the joints, tensile failure occurred at Ti-Ni interface due to the presence of the intermetallic compounds at this interface. Fracture surface analysis reveals that the tensile fracture path is along the intermixing zone of titanium and nickel interlayer.