A DISCUSSION OF THE SUSCEPTIBILITY OF AISI 410 TO STRESS CORROSION, AND MEANS OF ELIMINATING THE STRESS-CORROSION PROBLEM
AISI 410 stainless steel, tempered at 650 deg F for two hours to Rockwell hardness (Re) of 36 to 42, is susceptible to stress-corrosibn attack in high-temperature, high-purity waters. The time-to-failure is affected significantly by the water chemistry. Metallurgical factors contributing to the stress-corrosion characteristics are reviewed. AISI 410, tempered at 1125 deg F minimum (Rc 26) and not over 1350 deg F for four hours minimum, is not susceptible to stresscorrosion failures. Theories are offered that contribute to this immunity. The importance of proper heat-treat practices for maintaining the resistance-to-stress corrosion attack is emphasized. 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 that produced failure in unplated material or caused accelerated failures under conditions that did not produce failure in unplated material. Factors that may have contributed to the anomalous results are discussed. AISI 410, tempered at 1125 deg F or higher, showed an increased tendency to pitting attack in oxygenated waters. The extent of the attack is not significant for most applications in pressurized water reactors. Chromium electroplates up to 0.002-in. thick did not offer any significant advantages in minimizing the pitting attack. Because of the anomalous results and other problems associated with chromium electroplates, it was recommended that this deposit not be used for the protection of AISI 410 or equivalent material against general or stress-corrosibn attack. Initial studies on the use of gold electroplate for corrosion protection were not encouraging. Nickel deposits (0.002-in. to 0.003-in. minimum) may offer the necessary protection, but additional studies, as recommended, are required. When properly incorporated into a specific production design and effected by a properly designed and controlled process, shot peening will protect hardened (Rc 36 to 42) AISI-410 stainless steel from stress-corrosion failure in high-purity waters at temperatures up to 300 deg F. This protection will continue for a useful finite period at stresses up to 60,000 psi and indefinitely at stresses up to approximately 45,000 psi, about one-third of the yield strength. Before shot peening can be used for protection against stress-corrosion attack, consideration must be given to the effects of the environment, anticipated stresses, and temperature of application on the fadeout of the surface residual layer. For most applications, establishing adequate process and quality-control procedures should not be a problem. The basic data developed on shot peening of AISI 410 could be made applicable to other susceptible alloys as a means for protection against stress-corrosion attach. (auth)
- Research Organization:
- Knolls Atomic Power Lab., Schenectady, N.Y.
- DOE Contract Number:
- W-31-109-ENG-52
- NSA Number:
- NSA-15-031129
- OSTI ID:
- 4840127
- Report Number(s):
- KAPL-2155
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-61
- Country of Publication:
- United States
- Language:
- English
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