Microstructural evolution and weldability of dissimilar welds between a super austenitic stainless steel and nickel-based alloys

摘要: Microstructural evolution and solidification cracking susceptibility of dissimilar metal welds between AL-6XN super austenitic stainless steel two nickel-based alloys, IN625 IN622, were studied using a combination electron microscopy, differential thermal analysis, Varestraint testing techniques. Welds prepared over the entire dilution range (where was determined with respect to as base metal). The effect processing parameters filler chemistry on fusion zone composition, microstructure, resultant weldability investigated. Iron additions weld (which occur increasing dilution) increased segregation potential Mo Nb. This behavior attributed reduction in solubility Nb austenite iron additions. inferred from available binary phase diagrams. IN622 formed single interdendritic at end solidification, amount this secondary not sensitive changes dilution. relatively high temperature led narrow for IN622. In contrast, exhibited NbC Laves phases regions, total decreased Solidification terminated formation constituent low and, thus involving wide. sensitivity independent level, while produced IN62,5 decreasing dilution/cracking relation is controlled by that forms terminal stages solidification. good resistance small range. poor wide