Technical Note: Intergranular Corrosion and End-Grain Pitting in Type 304 Stainless Steel by Various Test Methods Available to Purchase

Laboratory techniques^1-3  have been proposed that simulate a variety of cooling rates that can occur through the sensitizing range of temperatures in Type 304 stainless steel. The writer^1,2  has proposed the use of the Jominy end-quench test, with the oxalic acid etch test (ASTM A262A) being made along a polished length of the test bar (corresponding to a longitudinal section out of a commercial bar or billet product). In brief, the use of the Jominy test reveals the susceptibility to intergranular attack of a particular heat continuously cooled from the solution temperature. A good heat shows little or no grain boundary ditching from fast to very slow cooling which means that a heavier section can be produced from it without a problem in the A262A test. The heat to heat differences in the susceptibility of Type 304 to intergranular corrosion (sensitization) are probably due to the presence of...