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建立了Ti C/Inconel 718复合材料体系选区激光熔化三维有限元模型,在考虑了相变潜热,热传导/对流/辐射多重传热机制和随温度变化的热物性参数条件下,使用ANSYS二次开发语言APDL实现了高斯激光热源的移动,并利用“生死单元”完成了多层多道的能量加载,研究了其选区激光成形的热物理机制。结果表明:温度变化率与工艺参数(激光功率和扫描速度)存在正对应关系,最高可达7.03×10~6℃/s。当扫描速度过快(300 mm/s)或激光功率过低(50 W)时,获得的熔池温度低(1991℃),液相存在时间过短(0.29 ms),而且液相量少,粘度大,不利于液相金属在粉末间隙中的铺展和润湿,易于在制件中形成不规则孔洞,增加制件孔隙率;在优化的工艺参数P=100 W,v=100 mm/s下,重熔深度(15.1μm)、重熔宽度(35.0μm)、液相存在时间(1.2 ms)、熔池最高温度(2204℃)和温度变化率均较为合适,易于获得冶金结合良好的SLM制件。对Ti C/Inconel 718混合粉末进行了选区激光熔化实验,验证了模拟结果的正确性。
The three-dimensional finite element model of laser melting of Ti C / Inconel 718 composite system was established. Based on the second phase of ANSYS, considering the latent heat of phase transformation, the multiple heat transfer / convection / radiation heat transfer mechanism and the thermophysical parameters with temperature, The language APDL realizes the movement of the Gaussian laser heat source and completes the multi-layer multi-channel energy loading by using the “life and death cell”, and studies the thermal physical mechanism of the selected laser forming. The results show that there is a positive correlation between temperature change rate and process parameters (laser power and scanning speed), up to 7.03 × 10 ~ 6 ℃ / s. When the scanning speed is too fast (300 mm / s) or the laser power is too low (50 W), the resulting bath temperature is low (1991 ° C), the liquid phase is too short (0.29 ms) Viscosity is not conducive to liquid metal in the powder gap spread and wetting, easy to form irregular holes in the workpiece, increase the porosity of the workpiece; the optimal process parameters P = 100W, v = 100mm / s , The remelting depth (15.1μm), the remelting width (35.0μm), the liquid phase presence time (1.2ms), the maximum temperature of the molten pool (2204 ℃) and the rate of temperature change are more suitable for easy metallurgical bonding SLM Parts. The selective laser melting experiment of Ti C / Inconel 718 mixed powder was carried out, which verified the correctness of the simulation results.