Research On Residual Stress Ofthe Pressure Resistant Vessel And Finite Element Analysis

In viewof the current post weld heat treatment specification on thick plate butt (thickness>125mm) is general, a research of heat treatment test has been made on the butt joint (δPWHT-l50mm) based on an analysis of welding residual stresses, the results showed that the residual stress of the root area of the thick butt joint from thickness direction before heat treatment was600MPa, The decreasing range of the residual stress of weld zone from thickness direction and plate direction was64%and56%after PWHT,The measurements of Leeb hardness also showed thathardness decreases20%-25%after the heat treatment.The Stress-strain variation characteristics of welded joint of the cylinder under hydrostatic load were studiedby means of the Stress-strain On-Line Monitoring system and numerical simulation technology in thispaper. The results showed that the maximum of tensile stress is161MPa. the maximal deformation zone is found on the top point of B6girth weld which connecting the circular tube and taper cylinder. Percentage ratio of the high stress concentrated area among the whole weld is28%. It presents circumferential distribution from the top point of B6girth weld to both two sides, with theincrease of the structural change.the stress concentration degree is found to be increased. High stress condition from welding seam and heat affected area of the heat-exchanger hull has been decreased to50%-80%after overall heat treatment.The welding residual stresses in girth weld of Inconel-600furnace tube are measured by blind-hole method. The result showed thatthere has residual stress value between400MPa and750MPa in the seam center to fusion line. The decreasing range of the residual stress of girth weld center and heat affected zone was72%and36%by vibratory stress relief (VSR)technology.