Carpenter 20Cb-3 strip in the stabilized, TIG welded and solution annealed conditions has been sensitized in the range 1050 to 1625 F (566 to 885 C) prior to intergranular corrosion testing in the Huey, ferric sulfate-sulfuric acid, nitric-hydrofluoric acid and Strauss tests. In stabilized annealed material, the sensitization temperature producing maximum susceptibility is about 1450 to 1500 F (788 to 816 C). Welded plus sensitized material showed susceptibility to intergranular corrosion immediately adjacent to the weld with the most severe sensitization temperature being about 1250 F (677 C). Stress relieving stabilize annealed or welded material in the range of about 1100 to 1600 F (593 to 871 C) is not recommended unless prior testing or experience indicate satisfactory performance. Huey rates following a 1250 F (677 C) sensitization increase as the annealing temperature is increased in the range 1725 to 2250 F (941 to 1232 C). Rates following a 1400 F (760 C) sensitization increase with a 2050 F (1121 C) anneal and decrease for 2200 F (1204 C) and higher treatments. The attack in stabilize annealed material sensitized at 1450 F (788 C) is attributed primarily to M6C. M23C6 plays a role at lower temperatures particularly in the as-welded or solution annealed conditions. Sigma phase can form at the higher sensitization temperatures.
Custom 450 is a martensitic precipitation hardenable stainless steel. The strengthening mechanism during aging is attributed to precipitation of a very fine Laves phase. The precipitate was found to be relatively stable with respect to coarsening at aging temperatures above 811 K (1000°F). The aging reaction is accompanied by austenite reversion. The decrease in hardness and strength and increase in impact strength with increasing aging temperature and time when aging above 811 K are shown to be related to the increasing reverted austenite content of the alloy. Data are presented showing the effect of heat treatment on resistance to stress corrosion cracking. The relationship of cracking to toughness and general corrosion resistance is discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.