STRESS CORROSION BEHAVIOR OF X70 PIPELINE STEEL IN SIMULATED SOLUTION OF ACID SOIL

Stress corrosion cracking(SCC) of X100 pipeline steel in simulated solutions of acid soil environment located at Yingtan area was investigated by slow strain rate test(SSRT),SEM observation of fracture surfaces and potentiodynamic polarization curves.The results showed that SCC exhibited a transgranular cracking mode.The applied polarization potential played an important role in facilitating SCC.Within anodic potential range,the X100 pipeline steel was controlled by anode process and was insensitive to SCC,but intergranular corrosion appeared.When X100 pipeline steel was controlled by combined anodic and cathodic processes,the stress corrosion sensitivity was low,and the crack grew slowly.But as the applied cathode potential lowered further to a range of only controlled by the cathodic process,hydrogen embrittlement mechanism played the major role and the cracks developed quickly.