Study On The Low-stress Non-deformation Welding Technology Of Hull Girder Structure

The application of beam structure is an important way to improve the strength,performance and bearing capacity of the whole structure.Welding is the main way for processing beam structure,welding process must follow the production of welding residual stress and deformation,the deformation and stress of the welding is a important factor of the formation of various sorts of welding defects,and the cause for welding thermal strain embrittlement,directly affects the manufacturing quality and using performance of the beam structure.Therefore,correct understanding of the formation of welding stress deformation mechanism,effect and influence,master the methods of control and adjust the welding stress and deformation,to improve the manufacturing quality and service performance of beam structure has very important significance.This study is Q345 steel T beam structure as the research object,based on thermal elasticplastic mechanics theory,adopt the method of numerical simulation for conventional welding and low stress deformation mechanism of welding two cases on the research and analysis.It provides a theoretical basis and basis for improving the current welding process and realizing the welded low-stress and non-deformation of beam structure.The specific research contents of this paper are as follows:(1)Using ANSYS finite element software,set up suitable for T type beam structure of bidirectional two three-dimensional finite element model of the welding process,calculate and get T beam structure in the process of conventional welding temperature field and thermal elastic plastic stress and strain distribution of change rule.(2)Aiming at low stress and deformation of welding numerical simulation based on the finite element model,due to the following heat generate rapid cooling heat sink,the welding temperature field compared with the conventional welding distortion,the temperature of the heat source center after there will be a plunge in process,and heat sink area for the temperature field of the bottom and make huge formed between the heat source and heat sink temperature gradient,and after the heat sink with heat sink departure there will be a little higher temperature,forming a similar to the temperature field of the saddle,but compared with the conventional welding process temperature is low;Due to the effect of rapid cooling of the heat sink at the same time,make the weld zone metals quickly have a nasty cold contraction after the heating process,which in turn makes the compressive plastic strain before the reduced,at the same time,the existence of the heat sink will be between the heat source and heat sink has cooled metal to produce strong stretching,and increase its tensile plastic strain,the weld area and near the weld zone metals strain decreases,and reduce the residual stress.(3)Using the methods of comparative study,the low stress on the welding structure welding,no deformation of heat source and heat sink distance D and the cooling intensity of heat sink two factors were studied,so as to explore the influence factors of low stress no deformation of welding.By comparing the simulation studies have found that when the heat sink cooling intensity is fixed,the distance between the heat source and heat sink is relatively close,butt welding structure of heat sink drawing effect is relatively small,after welding residual stress and strain of the improvement is not obvious;When the distance between the fixed heat source and the heat sink is fixed,as the cooling intensity of the thermal sink increases,the tensile effect of the thermal sinking welding structure will gradually increase.