Effect of Grain Boundary Engineering on Intergranular Corrosion Resistance of Incoloy825 Alloy

Grain boundary engineering (GBE) was carried out on nickle-based alloy tube material Incoloy825 by cold drawing using a draw-bench for factory production and subsequent annealing. The intergranular corrosion (IGC) testing was performed to study the effect of GBE on the IGC resistance of Incoloy825 alloy. The results show that the proportion of low ∑CSL (the reciprocal of the coincidence site lattice density for grains on both sides of grain boundary no higher than 29) grain boundaries in Incoloy825 alloy could be enhanced to more than 75%, so the IGC resistance of Incoloy825 alloy improved greatly. The enhancement of IGC resistance of Incoloy825 alloy after GBE was attributed to the formation of many inter-connected ∑3ⁿ-type triple junctions, such as ∑3-∑3-∑9 and ∑3-∑9-∑27.