Numerical Simulation Of Build Up Welding Process And Deformation Of Thin Cylinder Inner Wall

In the petrochemical,marine,construction machinery,vehicles and other industries,the production of large-size components are widely used in the production of multi-layer multi-pass welding.Since larger sizes of these components,a larger deformation often occurs after welding,and the welding deformation correction is more difficult.In recent years,the requirements of the pressure vessel are gradually increased,especially in deformation control of welded structures.Axial and radial contraction is produced during the welding process of thin-walled cylindrical structure with large-diameter,causing its size accuracy reduced and assembly difficulty increased.To solve this problem,enterprises often use physical testing as the basic method.However,a large number of tests make the production cost increase.Only by experiment and experience can no longer meet the actual production requirements.Therefore,reducing Multi-layer multi-pass welding produced by the welding deformation is particularly important.In order to solve the problem of large welding deformation after welding and assembly difficulty,the influence of welding process parameters on welding temperature field and welding deformation was simulated by Marc software.The component model under different welding processes was established and calculated.The welding temperature field and post-weld deformation behavior were analyzed.The best welding process parameters are got to provide theoretical reference and support for the actual design of the welding process.The results are as follows: 1.Different welding sequence,different temperature gradient of surfacing zone,different temperature field are formed by adjusting the welding sequence,welding speed,edge reserved width,The distribution of temperature field affects the distribution of stress field,and the distribution of stress field plays a decisive role in the deformation after welding.The welding sequence is the first layer from the edge to the inner cylinder welding,the second layer from the edge of the inner cylinder welding when welding the minimum amount of deformation of the cylinder.2.The faster the welding speed,the smaller the deformation of the cylinder after welding.However,when the welding speed reaches 4 times of the initial speed,the deformation after welding is abnormal,and normal welding cannot be achieved.Compared with the other factors studied in this paper,the welding speed has little effect on the change trend of the deformation of cylinder after welding.Therefore,it is recommended to use an initial speed of 0.00534 m/s.If the welding speed is too high,the temperature of the weld pool is not enough,defects such as incomplete penetration,unmelted weld formation and poor weld formation occurs,and product quality is affected.3.Within 0~0.083334 m,with the increase of the reserved length at the edge,the deformation of cylinder tip after welding decreases uniformly.However,when the reserved length at the edge of the base metal is 0.083334 m,the torsion distortion of the barrel body is greatly affected,which may affect the product quality.It is suggested that the cylindrical weldment with an outer diameter of 1.750 m and a thickness of 0.050 m should have a preset length of 0.066667 m at the edge of the base metal.At this time,the amount of deformation after welding at the end is small,and the trunk body does not appear to be greatly distorted.4.When the number of surfacing layers is within 1~4 layers and the thickness of surfacing layer is determined,the cylinder deformation will have a large multiple with the increase of the number of surfacing layers.In order to ensure the preservation of the quality of the cylinder wall and consider the cost of production,the surfacing can not only a layer,but also overlay layer too much.So the general can build two layers,both to meet the quality requirements in the cost of allowable range.The results are as follows: 1.When single heat source is used,the welding sequence is the first layer from the edge to the inside of the cylinder,and the second layer from the edge to the circle cylinder welding within the cylinder when the end of the deformation of the smallest amount.2.The use of dual heat source,using the welding sequence for the first layer from the cylinder to the edge of the cylinder began to build welding,the second layer from the same cylinder starting to the cylinder edge welding when the cylinder ministry of the deformation of the smallest.3.Compared with single heat source and double heat source,it is found that the four kinds of welding sequence of double heat source model all have less deformation after welding than those of the best heat source technology.The optimum welding process of dual heat source model produced after welding deformation is 81.668 % less than the best single-heat source welding deformation after welding.However,the dual heat source cylindrical members have a greater distortion than the single heat source members welded body.