数值计算与实验法相结合估定激光条件下原位反应的温度

Assessment of In-situ Reaction Temperatures under Laser Condition by Combining Numerical Calculation and Experiments

摘要:

用实验法获得了激光熔覆反应合成TiCp／Al复合材料过程激光突然停止时刻的显微组织；在已开发的激光表面熔凝过程三维瞬态温度场和流场模拟程序的基础上。考虑了激光熔覆反应过程的特点。用试错法改变原位反应各自的反应温度并依此温度分别将反应热对温度场的影响计人数值计算，将计算得到的温度与激光突然停止试验组织状态图的位置线进行比较，估定出了不同原位反应的发生温度；以不同参数进行工艺试验并进行模拟计算，比较熔覆层与基体界面结合处的金相组织和模拟计算温度对应的情况，验证了估定温度的可靠性；激光熔覆条件下原位反应温度的确定。为合理选择加工参数并优化工艺提供了参考依据。

Abstract:

A microstructure photograph was obtained when laser beam was turned off suddenly during laser cladding to synthesize TiC,,/Al composite. Based on the developed 3-D transient temperature field and fluid flow field simulation program for laser remelting, cladding reaetion features were considered and trial-and-error method was employed to choose every in-situ reaction temperature. According to the temperatures, the reaction enthalpies were added into temperature field calculation. Comparing the simulated temperature with the position lines of the different microstructure zones of the laser sudden stop test, the in-situ reaction temperatures under laser condition could be assessed. Some different parameters of processing were selected for the tests and numerical calculation. Through the agreement between the interface microstructure of the substrate and the cladding layer with the simulated temperature lines, the reliability of the assessed temperatures were proved validly. The assessed temperatures under laser condition could provide a reference for choosing the reasonable processing parameters and the optimized scheme.