2D transient model for rapid laser remelt

A two-dimensional transient model for high speed laser remelt was presented by solving the heat conduction and convection equations through finite element method and multigrid method.The time dependent physical process of laser remelt under CW laser and pulse laser with high scanning speed (HSP)(2m/s) and lowscanning speed (LSP)(0.2m/s)were simulated.The result shows that the scanning speed has big impact on the streamline and the distribution of the composition.It also shows that the same area on surface may be heated by multi-pulses of laser under LSP while it only be heated by one pulse under HSP.The result indicates that during laser remelt,the surface of the melt pool changes,the middle hollows and the edge reises.In addition,the shape,the size,the average cooling rate of the pool and the cooling rate at the edge of the pool can be obtained through the results.These cooling rates are useful to analyze the microstructure.