Metallographic Contrasting of Weld Joints on Duplex Stainless Steel

Abstract

Abstract The microstructure of a duplex stainless steel, e. g. 1.4462 (X2CrNiMoN22 – 5 – 3), is half austenite and half δ-ferrite. The challenge for the metallographer is to clearly determine the austenite / δ-ferrite quantity ratio, also in the weld metal and in the heat-affected zone and to find clear evidence for the presence of possible, detrimental precipitations of intermetallic phases. This is all the more difficult as both – austenite and δ-ferrite – appear light under the microscope when using standard etchants and as twins, which are typical of austenitic microstructures in the as-rolled condition, do not form in the weld metal. This work will thus present preparation methods which allow for a clear distinction of the microstructural constituents, austenite and δ-ferrite, as well as for a clear determination of the quantity ratios.