The effects of crystallographic orientation relationship at ferrite/austenite (α/γ) interface on sigma phase formation in a duplex stainless steel weld metal were studied. Crystallographic orientations of ferrite and austenite grains in the base and weld metals were determined by electron backscattered diffraction and the crystallographic orientation maps were drawn by orientation imaging microscopy. Sigma phase formed at one side of the α/γ interfaces along intragranular austenite. The crystallographic orientations at ferrite/austenite interfaces where sigma phase forms deviated largely from the Kurdjumov-Sachs (K-S) orientation relationship. The minimum deviation angle for sigma phase formation decreased with increasing annealing time.
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