Stress Corrosion of Steels For Aircraft and Missiles

Atmospheric stress corrosion tests have been conducted on alloy and stainless steels intended for use in high-speed aircraft and missiles. The results of these tests showed that very high strength alloys hardened by heat-treatment, like many nonferrous alloys used in conventional aircraft, are under certain conditions susceptible to atmospheric stress corrosion cracking. Tempering at temperatures of 1100 F and above confers resistance to stress corrosion. Also, the test results indicated that austenitic stainless steels hardened to very high strength levels by cold working are not susceptible. Protective coatings that are anodic to steel appear to be very effective in preventing stress corrosion. A correlation between the specimen tests presented in this paper and service performance has not been established. The test results should be regarded as a guide to effective utilization of steels in aircraft and missile applications, but they should not be regarded as a direct indication of expected service performance.