Welding Procedure Optimization Study For Thick Plates Of High Strength Steel Of Legs

With the enlargement of marine engineering and its structure, and the trend of environmental deterioration as the application of the structure extending into deeper ocean, the requirement of its strength becomes increasingly demanding. Thus, thick plates with high strength materials are being applied more widely than before. In this paper, finite element methods are accepted to analysis the influence of preheat temperature, heat preservation and slow cooling measures, welding speed and welding constraint conditions on welding deformation, welding stress and welding residual stress during the welding process of small assemblies. And according to the calculated results, the welding parameters are optimized.By the study, the conclusions about welding deformation are as followed:Welding deformation is reduced as preheat temperature increases; Welding deformation is reduced as heat emission coefficient increases; Welding deformation increases slightly as welding speed increases; and large welding deformation appears without proper welding constraint conditions. The conclusions about stress:The influence of preheat temperature, heat emission coefficient and welding speed on welding stress and welding residual stress are complex. The variation trends of welding stress and welding residual stress for different node positions are different. Thus, specific analysis methods should be considered according to different issues. The change of welding constraint conditions may reduce the welding stress and welding residual stress, but, we should consider the welding deformation at the same time. So, proper welding constraint conditions are necessary.According to the calculation results of the welding deformation, welding stress and welding residual stress, the impact of the various factors mentioned above are analyzed and optimized comprehensively. So the most harmonious parameters for thick pates of high strength steel of legs are put forward.