H13钢表面激光熔覆316L/H13+20%WC复合涂层温度场数值模拟

Numerical Simulation of Laser Cladding 316L/H13+20%WC Composite Coating on H13 Steel Surface

H13钢常充作热作模具材料,在高温高压等工作环境中极易产生磨损、开裂等失效的问题,激光熔覆是一种有效的再制造方法。然而,由于激光熔覆骤冷骤热的特点,使得成形过程温度梯度及冷却速率过大,常导致热应力过大而引起涂层开裂。对H13钢表面激光熔覆316L/H13+20%WC复合涂层温度场进行数值模拟,研究成形过程温度梯度、冷却速率随时间的变化规律,以及基体预热对温度梯度和冷却速度的影响。同时,在H13钢基体上进行了复合涂层激光熔覆成形试验,以便对数值模拟结果进行验证。试验结果表明,预热可明显降低温度梯度和顶层冷却速率,对于试样表面裂纹产生具有一定的抑制作用。研究结果为H13钢表面激光熔覆改性及模具修复提供了参考依据。

H13 steel has often been used as a hot-work die material. However, it tends to undergo failure because of wear and crack generation under high-temperature and high-pressure working conditions. Laser cladding is an effective remanufacturing method for such materials. However, the temperature gradient and cooling rate of the formation process are very large owing to rapid cooling and heating characteristics, often inducing excess thermal stress and cracking of the coating. Herein, a numerical simulation of a laser cladding 316 L/H13+20%WC composite coating on H13 steel surface was performed. The variation in the temperature gradient and cooling rate with time and the influence of substrate preheating on the temperature gradient and cooling rate were studied.Moreover, to verify the numerical simulation results, a laser cladding formation test of the composite coating was conducted on the H13 steel substrate. Experimental results show that substrate preheating can significantly reduce the temperature gradient and cooling rate on the top surface of the coating and exerts a certain restraining effect on the cracks of the sample surface. The findings of this study provide a reference for the laser cladding modification and repair of H13 steel dies.