Stree Corrosion Cracking of Austentic Stainless steel under Compressive Stress

Stress corrosion cracking (SCC) of austenitic stainless steel in a boiling 42% MgCl₂ solution under compressive stress was investigated. Specimens with surface residual compressive stress, U-bend specimens and notched compressive specimens of modified WOL type were used. The results showed that SCC under compressive stress occurred for these three type specimens after 110, 73-100 and 262-324 hours respectively. Fracture surfaces of SCC under compressive stress were quasi-cleavage characterized by stratified rock structure and striation-like pattern rather than river marks or fan pattern under tensile stress.
The incubation period of SCC under the compressive stress is much longer and the propagation rate of the crack is much slower than that under the tensile stress. Therefore, SCC under the compressive stress usually can not occur if there exists simultaneously the tensile stress in a apecimen or structure.
The possible role of hydrogen in SCC of this system is discussed.