Influence Of External Restraint And Welding Technology On Inherent Deformation Of Welded Joints Of Low Alloy High Strength Steel

As an important material processing technology,welding is widely used in production.Welding products can be seen everywhere,such as cars,ships,subway,high speed rail.During the welding process of these large,complex and thin plate products,the welding material is partially heated and melted under the action of external heat source,which is accompanied by the conduction of heat in the interior of the material and to the external environment.Therefore,the temperature gradient of the inner part of the workpiece is larger.Welding heat cycles in different regions are not the same,and this phenomenon runs through the whole welding process.Finally,inevitably produces welding deformation.For large structures,welding deformation will not only affect the normal process of subsequent production,but also weaken the bearing capacity of the structure,and affect the stability,appearance,and dimensional accuracy of the overall structure.When the welding deformation of welded structures exceeds the tolerance range of manufacturing precision,the deformation of the welded structure must be corrected.The correction process not only increases the time cost and increases the production cost,but also causes the instability of the quality of the production products.Therefore,it is important to study the influence of external restraint and welding technology on the inherent deformation of welded joints of low alloy high-strength steel.Based on the ABAQUS finite element analysis software,this paper uses the thermo-elastic-plastic finite element analysis method to simulate the welding process of welded specimens in the free state.At the same time,a thermo-elasto-plastic finite element method considering contact nonlinearity was developed for specimen welding under external restraint.In addition,the plates were subjected to bead welding tests in the free state and under different external restraint conditions.Then,their welding distortion was measured.Comparing the calculated results with the experimental results,the effectiveness of the developed thermal-elastic-plastic finite element analysis method was verified.Then,the developed finite element analysis method was used to study the effect of external restraint on the out-of-plane deformation of the T-joint of the plane floor plate and study the out-of-plane deformation of the T-joint of the curved floor plate.Finally,the typical T-joints under structural restraint,free state,and external constraints were simulated,and the extracted inherent strain parameters were brought into the rib structure to obtain the out-of-plane deformation,and the external constraints and welding technology are The influence of the inherent deformation of low alloy high-strength steel welded joints was studied.The conclusions are summarized as follow:1)For plate surfacing,the distribution of transverse plastic strain in the weld area and its vicinity is more uniform,and the closer the restrained position is to the weld,the smaller the angular distortion.when buckling distortion occurs in the thin-plate welded joint the external restraint cannot effectively reduce the out-of-plane deformation.However,when buckling distortion does not generate after welding the external restraint can reduce the out-of-plane deformation to certain extent.2)When the restraint condition is the same,the total out-of-plane deformation of the T-joint by the bilateral welding is less than the total out-of-plane deformation of the T-joint by single side welding.When the welding technology is the same,external restraint can effectively reduce the out of plane deformation of T joints.The closer the restraint fixture is to the weld,the more obvious the effect of reducing the out of plane deformation of the T joint.3)The flexural rigidity of T-joint of the curved floor plate is larger than that of T-joint of the plane floor plate.When the angular deformation is the main deformation,the total deformation of T-joint of the curved floor plate is less than that of T-joint of the plane floor plate.When the longitudinal compression force is the same,the bending deformation of he curved floor plate is larger than that of the plane floor plate.When the longitudinal shrinkage dominates the deformation,the total deformation of the T-joint of the curved floor plate is larger than that of T-joint of the plane floor plate.4)The free-state extraction data is brought into the intrinsic strain model,and the calculation result is larger than that of the thermo-elastic-plastic method.When the externally constrained extracted data is brought into the inherent strain model,the deformation results are small.The structural restraint extracted data is brought into the inherent strain model,and its deformation results are closest to thermo-elastic-plastic method.In order to improve the accuracy of the calculation,structural restraint must be considered.