Effect of Heat Treatment on the Grain Boundary Chemistry and the Resistance to Intergranular Corrosion of Alloy 600 and Alloy 690

摘要

GRain boundary impurity segregation and carbide precipitation have been studied in two series of experimental alloys of the type 600 and 690, as a function of heat treatment. The resulting microstructures have been characterised and tested in 30percent NaOH + 10percent Na_2SO_4 solution at 350 deg C for susceptibility to intergranular corrosion. It was found with both types of alloys that resistance to intergranular attack has a close dependency on the segregated impurity concentration, and the grain boundary microstructure, i.e. morphology and distribution of intergranular carbides.