Grain-Boundary Chemistry and Intergranular Fracture in Austenitic Nickel-Base Alloys—A Review

Austenitic nickel-base alloys such as alloys 600 (UNS(1) N06600), 690 (UNS N06690), and X-750 (UNS N07750) have been found to be highly susceptible to environmentally-induced intergranular cracking. It is now well established that the structure and chemistry of grain boundaries play an important role in this process. In particular, carbide precipitation, chromium depletion, and impurity segregation can significantly affect the intergranular cracking behavior of these alloys. This paper reviews the intergranular cracking behavior of these alloys as influenced by such grain-boundary chemistries.