Microstructural study of super Ni laminated composite/1Cr18Ni9Ti steel dissimilar welded joint

Super Ni laminated composite and 1Cr18Ni9Ti stainless steel were welded by the tungsten inert gas process with the Cr25–Ni13 filler alloy. The microstructure, element distribution and phase formation near the fusion zone were evaluated by standard technique. Results indicated the formation of four main regions: the fusion transition region on the 1Cr18Ni9Ti steel side, the fusion transition region on the super Ni laminated composite side, a columnar crystal weld region and the weld centre region. The microstructure on either side of the weld was characterized by strong directionality and changed from columnar austenite to equiaxed austenite in the weld centre. A Ni, Fe and Cr element transition region, about 30 μm wide, was formed at the fusion zone on the super Ni side. The phase formed into welded zone was composed mainly of austenite, δ-Fe, γ-Ni(Cr, Fe) and FeNi intermetallic compounds.