Formation of intermetallic phases in aluminium-austenitic stainless steel friction welds

The principal difficulty in joining aluminium to austenitic stainless steel is the possible formation of embrittling iron-aluminium intermetallic compounds. Friction welding offers a satisfactory route to tackle this problem. The phases that form in such welds have been analysed in the current investigation through several techniques. While the presence of many elements hinders precise stoichiometric designation of the phases, the evidence obtained indicates that compounds of the type Fe2Al5 and FeAl3 do form in joints of this kind. Though these phases are highly brittle, friction welding conditions can be optimised such that the intermetallic layer is restricted to a narrow width and joint mechanical properties are not adversely affected.