Finite Element Analysis Of Longitudinal Welding Temperature And Stress Fields For Sa580-Ⅲ Steel Thick Wall Cylinder

Generally, welding is very important in making the kernel pressure vessel. And welding quality directly determines the life of the equipment and security. Especially in multi-pass welding, thermal effects will result in temperature and stress and deformation, thus largely affecting the quality of welding.In order to better study on multi-pass welding and effectively provide the date of the welding for the actual project, the SA508-Ⅲsteel cylinder multi-pass longitudinal welding finite element model has been established by ANSYS finite element analysis software in this article. Using Gleeble-1500D Simulator, SH-CCT of SA508-Ⅲsteel is determined. At the same time, the SA508-Ⅲsteel of high temperature mechanical performance is measured. On this basis, heat generation rate as a welding heat source model, by distributed computing and element birth and death technology, the results of multi-pass welding temperature fields are calculated out. After that, the results of welding stress fields are got by heat-structure coupling method on the basis of the temperature fields.We can get the following conclusions form the SA508-Ⅲsteel SH-CCT curve: when the cooling rate is at 0.015℃/s~0.05℃/s range, the phase-changed products is Ferrite and Pearlite; when the cooling rate is at 0.1℃/s~7℃/s range, the phase-changed products is Bainite; when the cooling rate is at 20℃/s~80℃/s range, the phase-changed products is Martensitic; SA508-Ⅲsteel cross rate is greater than 60% at 950℃~1300℃temperature range form high temperature tensile test, indicating that it has good high temperature mechanical performance.Through temperature and stress results analysis, welding temperature fields is obtained; the heating rate of node-A is 353℃/s; the cooling rate is 68℃/s; this node stays for 4s above phase transition point (750℃); the maximum temperature is 1210℃; welding stress fields is obtained; welding had a great influence on welding joint in thickness direction; and approximately 100MPa of residual stress is produced in thickness direction; residual stress stay a certain of regularity in zone of stability, and the stress reduce constantly from the weld to the base metal; Residual stress distribution is more complicated in the ends of the weld; equivalent stress is the biggest in the weld seam and fusion zone, and achieve the material yield limit; total deformation is the largest in the weld seam, and total deformation is the smallest in the base metal; total deformation is 0.0025m and 0.00036m respectively.