Stress corrosion cracking occurs when the environment, material condition and mechanical loading achieve certain critical values. Additionally, intergranular stress corrosion cracking occurs when the grain boundary microstructure and microchemistry are altered in a specific fashion. This alteration may be the result of equilibrium impurity segregation, precipitation of active phases or depletion of passive film forming elements. Examples of each type include P segregation in rotor steels, Al3Mg2 precipitation in 5xxx series Al alloys and chromium depletion in thermally sensitized austenitic stainless steel, respectively. There are other possible grain boundary factors that could affect IGSCC such as impurity or precipitate effects on grain boundary sliding but these are less well understood and will therefore not be covered extensively in this review.
Keywords: intergranular, segregation, impurities, stress-corrosion