Control Of The Laser Welding Deformation Of The Thin Stainless Steel Plate

With the advantage of high speed,small heat-affected zone,narrow weld seam and good performance,laser welding is widely used in the field of aerospace, shipbuilding, automobile manufacturing, weapons manufacturing, pressure vessel manufacturing, civil and medical application.Precisely welding of thin plates is a difficult problem in the field of welding.To weld the large and thin components,the deformation is much lager,but the deformation can be controlled effectively using laser welding.And the weld seam has small and pure grain, and has high strength and plasticity. The strength of welding seam is not less than the strength of base metal .There are Nd:YAG dual-beam laser welding test of seat slide track and CO2 laser welding of C-GIS cabinet.Firstly,I summarize the factors that affect the laser welding deformation through theoretical calculations and experimental analysis. I respectively study the power density, welding speed, defocusing, laser pulse width, welding materials, the workpiece gap, surface contaminants and assist flow gas. Some of the obtained experimental data can be taken as the guide of the laser welding.Based on the finite element theory of welding process, I respectively derive and calculate the finite element process of temperature and stress field. I analyze nonlinear transient heat conduction temperature field with the method of space-time discretization ,and list the heat source model which will be used in temperature field. I analyze the thermal stress and deformation with the plastic theory and elastic-plastic finite element theory, described the solving process of the stress and deformation. Based on the heat elastic-plastic finite element theory, I predict the welding deformation with residual plastic strain method and inherent strain method.And I simulate the welding deformation using ANSYS software.Finally,I design the special welding fixture following laser welding process and deformation theory,and do two laser welding tests.For welding test of the slide track,I analyze and summarize from the aspects of appearance, penetration depth,weld seam width, weld defects and mechanical properties.For welding test of the C-GIS cabinet, I analyze and summarize from the aspects of appearance, dimension tolerances and sealing.