Research On The Texture Characteristics And Joint Deformation Anisotropy Of Aluminum Alloy Welds

With the rapid development of our country’s industry,the proportion of the use of aluminum alloys in our country’s industrial production has gradually increased.Due to the strong thermal conductivity of aluminum,the weld has a specific solidification form under different heat input.This special solidification form will make the texture distribution in the weld have a certain regularity,and this regular distribution form creates the anisotropy of the weld performance.With the help of advanced microscopic analysis methods,we have been able to study the influence of the distribution of texture of the weld on the properties from the mesoscopic grain scale.Through mesoscopic simulation,we can better understand the coordination between polycrystals,This is of great significance for understanding the causes of weld failure,improving the macro weld performance,and optimizing the welding process.In this paper,the laser weld of 1060 aluminum alloy are taken as the research object,and the crystallization morphology of the weld seam under different heat input is determined by thermal field simulation.The weld seams under different heat inputs were selected for in-situ tensile experiments,and the backscattered electron diffraction data were extracted under different strains.By analyzing the crystallographic information of different regions,the distribution law of crystal orientation was obtained,and the relationship between grain growth and crystal orientation was found out.For individual grain,according to Schmidt’s rule,the performance difference between different grains is analyzed,and the relationship between the grain growth and the property anisotropy is found by comparing the tensile properties of the weld in different directions.In the process of tension,the cooperative rotation of the crystal orientations in the grains was observed,and the rotation law was analyzed.Finally,using the finite element analysis software,through the crystallographic information obtained by the experiment,a 1:1polycrystalline modeling was carried out to restore the real distribution state of the weld grains.The simulation analysis focuses on the stress-strain distribution and value changes of the polycrystalline model during the stretching process,and the simulation results were compared with the experimental results.The results show that the tail of the weld pool shape,which determines the growth of grains in the weld,will gradually elongate with the increase of the welding speed.The growth of columnar crystals on both sides of the weld will gradually rotate towards the welding direction as the welding speed decreases.Columnar crystals growing longitudinally will appear in the middle of the weld,the crystal orientation showing disorderly at Low heat input high welding speed.With the increase of the heat input the growth of columnar crystals on both sides will incline towards the welding direction to form an included angle of close to45° finally.It can be inferred from the comparison of the pole Figs that the growth direction of columnar crystals highly coincides with [001] crystal orientation.The grain slip system whose [001] crystal orientation coincides with the tensile direction is prone to activited,the grain deformation is most difficult,if the normal direction of the {111} crystal planes is parallel to the tensile direction.In the process of tension,all grains show different degrees of lattice rotation,and the rotation path is related to the initial orientation of grains.Most grains tend to move in straight lines which will rotate towards the connection of [001] and [1 11] then continue to rotate in the normal direction of the connection or parallel to the connection direction,so as to realize coordinated deformation.In the process of tension,the grains with hard orientation will generate large stress,while those with soft orientation will reduce their own stress through plastic deformation.The boundaries of grains with hard orientation take on a higher strain,and cracks will emerge if the harder grains are at the edge of the tensile sample.