Effect Of Strain Hardening On Stress Corrosion Cracking And Welding Residual Stress In06Cr19Ni10Stainless Steel

The technology of strain hardening can significantly increase the yield strength of austenitic stainless steel, and thus reduce the wall thickness of vessel. Consequently, it can lighten the weight of vessel and achieve the light-weight of pressure vessels.This paper is supported by National "863" key project issues (2009AA044802)"The design, manufacture and maintenance of significant pressure equipment under extreme conditions". Based on the literature review in and out of china, through the room temperature tensile tests, slow strain rate tests and welding residual stress numerical simulation, this paper has studied the influence on mechanical properties, stress corrosion cracking performance and welding residual stress distribution of strain hardening for austenitic stainless steel06Cr19Ni10. These results can provide some reference for strain hardening process. The main conclusions of this paper are as follows:(1) The tensile strength for base metal and weld are affected less by strain hardening. But after strengthening425MPa stress, the elongation for weld are affected more by strain hardening, and its elongation is less than the minimum specified in the relevant standards25%.(2)As the strain increases, the amount of martensite produced by the base metal deformation increases. After strengthening8%strain, the lath deformation martensite can be observed through optical microscope, and there is not deformation martensite in the weld for strain hardening.(3) The welding residual stress can not be completely removed by strain hardening; but it will be significantly improved. As the strengthening stress increases, longitudinal and ring weld are improved more obviously, but it is not obvious for ball weld. After strengthening410MPa stress, pre-strengthening will increase the maximum of welding residual stress for longitudinal weld, but there is not obvious change for ring and ball weld.(4)In the temperature200℃and5%NaCl+0.5%acetic acid solution, as the strengthening stress increases, the sensitivity of stress corrosion for base metal increases. After strengthening425MPa stress, stress corrosion cracking occurred in the material. In the range of410MPa strengthening stress, there is no obvious stress corrosion cracking generated in the weld joints.