Numerical Simulation Of Welding Temperature Field And Stress-strain Field On The Joint Of X80 Pipeline Steel

Welding is a complicated process involving the arc physics, heat transfer, metallurgy and mechanics. And the welding phenomenon including the process of electromagnetic, heat transfer, metal melting and solidification, phase transformation during the cooling time and the welding stress and deformation, etc. With the rapid development of computer calculating ability and the advances of numerical calculation technique, numerical simulation with finite element analysis has become the most important means for studying the welding phenomenon.Via the finite element analytical system, this paper systemically discusses the welding process. And with the joint of the X80 pipeline steel as the research object, combined with the disciplines’ s basic theories of metal physics, welding transfer heat and mechanics. In addition, adopt the experiment and numerical simulation to simulate the temperature and stress-strain field of the joint of the X80 pipeline steel. Also via the thermal simulation method, expansion method and metallographic method to test the SH-CCT diagram. Using the finite element software SYSWELD produced by the French ESI company and use the double ellipsoid heat source model, in the meanwhile, considering the nonlinear relationship between material properties and temperature, and the interaction among temperature, microstructure and stress, simulating the whole welding process of the X80 pipeline steel and get the result of stress and residual stress’ s distribution. In addition, understand the welding thermal cycle curve of the weld, the fusion zone and the HAZ,which provide theoretical basis for develop further reasonable welding process parameters. The research results can provide theoretical guidance to the pipeline steel’s girth weld’s toughness matching principles, at the same time, which can provide fundamental basis for oil and gas pipeline’sservice safely.Via the monitoring temperature system, some points in the test model are measured during welding process by means of thermocouples.As a result, the experimental data is in perfect accordance with calculated data. In conclusion, doing by this way can firmly provide a basis for further research of stress and strain fields in the period of welding process.The welding transversally and longitudinally residual stress and distortion were also measured on the joint of the X80 pipeline steel. The distributive patterns of residual stress matched extremely well with the results of numerical simulation as well as testify the resuls of the numerical simulation.As it can been manifested by the research and numerical simulation,this paper establishes a feasible dynamic simulation method on 3D welding temperature and stress fields, which provides theory evidence and instruction and promotes the application of FEA on welding mechanics analysis and engineering.