X65MS埋弧焊管SSC环境下腐蚀沟槽产生原因分析OA

Hydrogen sulfide corrosion is the main cause of the oil and gas pipe failure.Hydrogen sulfide stress corrosion test(SSC)is conducted on a X65MS steel grade submerged arc welded pipe.It is found that numerous corrosion grooves appear on the tensile surfaces of all base materials HAZ and weld zones,all of which were perpendicular to the direction of tensile stress.By conducting tests on the physical and chemical properties,microstructure,hardness,and surface residual stress of the material,the corrosion characteristics of SSC were analysed and the reasons for the appearance of corrosion grooves in SSC samples were explored.Results show that the physical and chemical properties of the material meet the standard requirements,but there is a hard phase(M-A island structure)in the microstructure of the surface layer,and the hardness distribution is uneven,exceeding the standard specified 250HV0.3.After heat treatment of the material,the surface hardness was improved,with a maximum hardness of 226HV0.3.The residual stress on the surface decreased from 295 MPa to 123 MPa.Sampling was conducted for SSC retesting,and no corrosion grooves were found.The surface hardness and residual stress had a significant impact on the occurrence of corrosion grooves in the SSC test.By reducing hardness and controlling residual stress,the SSC performance of X65MS can be effectively improved.