为了在模具上加工出特定的毛化形貌和尺寸, 采用计算流体力学软件Fluent探究形貌成型机理, 建立了激光毛化过程3维瞬态模型。考虑热传导、热对流、材料热物性参量等影响因素, 采用焓法处理固液相变移动边界, 通过用户自定义函数加载激光热源, 计算得出熔池温度场与流场。基于数值模拟, 采用单因素轮换法进行了毛化工艺试验, 研究了激光功率密度、脉宽两因素对毛化形貌、几何参量的影响。结果表明,激光功率密度在2.04×104W/mm2~3.57×104W/mm2, 脉宽在100μs~1000μs之间;以氮气作为辅助气体, 可获得球冠状、凹顶球冠状、M状3种形貌。该结果对模具毛化种类具有指导意义。

In order to fabricate specific morphology and size on a mold by means of the laser texture, and explore the mechanism of the formation of topography, a three-dimensional transient model of the laser texturing process was established based on the Fluent software. The temperature field and flow field of molten pool were calculated, and the experimental parameters were determined: laser power density 2.04×104W/mm2~3.57×104W/mm2, pulse width 100μs~1000μs. The thermal conductivity, thermal convection, thermophysical properties of materials and other factors were considered. The enthalpy method was used to deal with the boundary of solid-liquid phase transition, the laser heat source was loaded through user defined function. Based on numerical simulation, the influence of laser power density and pulse width on the morphologies and geometrical parameters of laser texturing were studied by varying a single factor with nitrogen gas as the auxiliary gas. Spherical crown, concave crown and M shape were obtained. The results have guiding significance for mold texturing.