STRESS CORROSION CRACKING OF 316Ti IN 300℃HIGH TEMPERATURE WATER CONTAINING CHLORIDE IONS

The stress corrosion cracking(SCC) of 316Ti stainless steel(SS) in 300℃high temperature water containing chloride ions was investigated with slow strain rate tensile(SSRT) techniques.The results showed that the values of fracture time and extension ratio and fracture energy of specimens significantly decreased with the concentration of chloride content increased,while stress corrosion sensitive index would significantly increase with the concentration of chloride ions increased.316Ti SS was not susceptible to SCC when the chloride content was below 5 mg/L while transgranular and partially intergranular cracked when the chloride content was above 5 mg/L in aerated water.Stress corrosion cracks generally initiated from slipping steps or pits,maybe from the secondary phase ferrite.In propagation into the base metal,the cracks would be arrested by the secondary phase ferrite,so as to improve the resistance of SCC for 316Ti SS.Oxygen played a crucial role in SCC initiation and propagation of 316Ti SS in high temperature water.