Stress Corrosion Cracking and Hydrogen Embrittlement of High-Strength Fasteners
Rept. for Jun 1971-Jan 1972
AEROSPACE CORP EL SEGUNDO CA SYSTEMS ENGINEERING OPERATIONS
Pagination or Media Count:
Unexpected, brittle failures of high-strength fasteners on aerospace vehicles have been caused by stress corrosion cracking SCC and by hydrogen stress cracking HSC. Despite extensive study, much remains to be learned about the phenomena. The poorly understood failure mechanisms are difficult to differentiate, especially in the field. There is a growing use of the term SCC to describe failure by both mechanisms. Data are given to characterize the classes. For low alloy carbon steels heat-treated to yield strengths below approximately 160 ksi, stress corrosion is not a problem, nor is hydrogen embrittlement delayed cracking very common. Above 160 ksi, difficulties can occur. The high-strength, precipitation-hardening, stainless steels have varying degrees of resistance to stress-corrosion cracking and hydrogen embrittlement, depending upon strength level and heat-treating procedures that influence the microstructure.
- Properties of Metals and Alloys
- Couplers, Fasteners and Joints