304不锈钢激光焊接接头形貌与组织性能分析.pdfVIP

addition, the tensile test of joints welded under different processing parameters were conducted, and the tensile properties were related to the macro-morphology and microstructure of joints. When the joint obtains the appropriate macro-dimensions and fine grains in the fusion zone, it gets the best tensile properties and fractures in the base metal after tensile test. The morphology of fracture surface was examined via a scanning electron microscope. It is visible that large quantity of dimples is formed on the fracture surfaces, revealing that the welded joint fails in a ductile mode. Finally, according to the feature of weld shape of laser welding, a combined heat source model of double ellipsoid body heat source and gauss surface heat source was established. The dynamic simulation of temperature distribution of laser welding was realized by using FE software ABAQUS and the user subroutine which is in the FORTRAN language. From the aspect of macro-morphology, the welding pool boundary in simulation is in accordance with the fusion boundary in experiment, which verify the reliability of model. From the aspect of microstructure, the temperature distribution can predict the temperature gradient of liquid and the cooling rate of weld center, and further predict the tendency of solidification mode and the relative size of grains qualitatively. So the relation between the temperature distribution and microstructure of weld is studied. Keywords: Laser welding; Microstructure; Mechanical property; Temperature