Stress Corrosion Cracking Behavior Research Of 316L Stainless Steel In Saturated CO₂+Cl^-+H₂S

Stress corrosion crack is common corrosion forms of oil-gas field development and transportation.Austenitic stainless steel is the main metal meterials in oil field and petrochemical enterprise,which is used for anti-corrosion.With the extremely operating environment,austenitic stainless steel is easy to have stress corrosion crack.It is important to research stress corrosion crack of austenitic stainless steel in complex environment,and to control it.This paper uses slow strain rate test?SSRT?and constant strain pre-cracked?WOL?specimen test to research stress corrosion crack behavior of 316L stainless steel in saturated carbon dioxide and hydrogen sulfide with chloride ion,and analysis the influence of the concentration of H₂S and Cl^-.The main conclusions are as follows:?1?The result of SSRT shows that with the increase of concentration of Cl^-stress corrosion sensitivity index is small,316L stainless steel doesn`t have apparent tendency of stress corrosion in sat.CO₂+200ppmH₂S environment.With the increase of concentration of Cl^-,stress corrosion sensitivity index increased gradually in sat.CO₂+1600ppmH₂S and sat.CO₂+sat.H₂S environment.The result of appearance of fracture and energy spectrum analysis shows that the higher content is S and Cl element in the corrosion products.Stress corrosion of 316L is caused by the H₂S and Cl^-in this complex environment.The environment of saturated carbon dioxide and 1600ppm hydrogen sulfide with 5%chloride ion and saturated carbon dioxide and saturated hydrogen sulfide with 5%chloride ion are the most sensitive environment.?2?The result of constant strain pre-cracked?WOL?specimen test shows that the crack growth rate of 316L stainless steels is 2.67×10^-85.85×10^-8mm/s in the environment of saturated CO₂ and 1600ppm H₂S with 5%NaCl,and the crack growth rate of 316L stainless steels is 3.35×10^-84.37×10^-8mm/s in the environment of saturated CO₂ and H₂S with 5%NaCl.Stress corrosion cracking critical stress intensity factor K_ISCC?16.16MPamin the environment of saturated CO₂ and 1600ppm H₂S with 5%NaCl,and Stress corrosion cracking critical stress intensity factor K_ISCC?15.78MPam?3?The result of SSRT and WOL show that Cl^-is the main factor of stress corrosion cracking,and H₂S is the secondary factor of stress corrosion cracking.Corrosion form of316L stainless steel is anodic dissolution type in the environment of saturated carbon dioxide and saturated hydrogen sulfide with 5%chloride ion.The increase of H₂S concentration inhibited the progress of SCC after promoting it.