Chromium Electroplates for Corrosion Protection Of Stressed AISI 410 Steel In High Temperature, High Purity Water

The use of chromium plates for protection of AISI 410 steel against stress corrosion cracking gave anomalous results. The coating either offered protection under conditions which produced failure in unplated material, or caused accelerated failures under conditions which did not cause unplated material to fail. Factors which may have contributed to the anomalous results are discussed. Introduction of oxygen into 300 F-water systems caused accelerated stress-corrosion failures, especially for the chromium-plated samples, with applied stresses as low as 60,000 psi. From information presently available the use of chromium deposits is not recommended for corrosion protection of AISI 410 steel materials that are susceptible to stress corrosion and/or intergranular attack. AISI 410 steel tempered at 1125 F minimum, not susceptible to stress corrosion failure, indicated insignificant or no pitting attack after 6 weeks exposure in airsaturated water at 300 F. There are no significant advantages in the use of chromium plate to reduce general corrosion attack. There is a possibility that this coating, under certain conditions of application, may promote accelerated pitting attack. Cobalt-base alloys, such as Stellite 6, in contact with chromium-plated AISI 410 steel, tempered at 1125 F minimum, will promote accelerated dissolution of the chromium plate adjacent to juncture between Stellite 6 and chromium plate, and pitting of base metal in these areas. No attack of chromium plate in the crevice was noted, but accelerated attack of the base metal through the cracks in the chromium plate was noted in these areas. 5.3.2