Three-dimensional Numerical Simulation Of Fe-Mn-Si Shape Memory Alloy Laser Welding

Fe-Mn-Si shape memory alloy is both the shape recovery and driven functional materials, it has a low cost and good mechanical properties. In order to obtain a wide range of industrial applications, the welding performance of Fe-Mn-Si shape memory alloy is imperative. At present, researchs on the welding of shape memory alloy are few and all specific technology test, the studies on the welding thermal process have not been reported, while the mechanical properties and organizational changes of the welded joints are closely related to the temperature field and stress-strain field distribution during the welding process, these data are difficult to obtain through the test. Therefore, this paper uses the finite element method based on Ansys platform, through the establishment of accurate and reasonable heat source model, to obtain the dynamic temperature field and stress-strain field three-dimensional distribution of Fe-Mn-Si shape memory alloy plate laser butt welding of numerical simulation.According to the characteristics of laser deep penetration and considering the influence of nonlinear material parameters, phase change latent heat, the boundary heat transfer condition etc, the heat source is parameterized by the combination of a circular disk source with a Gaussian distribution of thermal flux with center on the top surface and a cone heat source through the thickness of workpiece, and the APDL subroutine is prepared to load and move the welding heat source, and establish a flat butt laser welding 3D numerical calculation model. To verify the correctness of the calculation model built by comparing the simulated weld size and test weld size.Through numerical simulation of Fe-Mn-Si shape memory alloy laser welding temperature field, this paper obtains the impact of the law of parameters such as laser power and welding speed on the weld pool morphology and the positive and negative dimensions of weld. Comparing the simulated weld size with the test weld morphology, the simulated results are in good agreement with the test results, both error size is in less than 12%, and thus prove that the model can be used for optimization of the laser welding process parameters and to predict the weld size and weld quality.This paper simulates the dynamic stress-strain variation during laser welding process on the basis of the temperature field calculations and analysis of Fe-Mn-Si shape memory alloy through the indirect coupling method, and focus on the analysis of the distribution of the resulting residual stress and deformation. Can be obtained, when heated, the high-temperature materials around the heat source under pressure stress, and the peak compressive stress exceeds the yield limit of Fe-Mn-Si shape memory alloy, the maximum value of residual tensile stress after welding is 247MPa, the maximum longitudinal shrinkage of the weld start end is 0.012mm, vertically away from the weld longitudinal contraction gradually decreases, while the maximum displacement ’difference in the z-axis direction between the weld center and the edge of plate’width in the weldment central section is approximately 0.0056mm, the angular deformation is small.