TiZrNiCuBe块体非晶合金激光焊接行为及温度场数值模拟研究

Laser Welding Behavior of TiZrNiCuBe Bulk Metallic Glass and Numerical Simulation of Temperature Fields

摘要:

采用数值模拟研究了Ti40Zr25Ni3Cu12Be20块体非晶合金激光焊接过程中的温度场变化和冷却速度变化规律, 分析了Ti基非晶合金在激光焊接过程中保持非晶态结构的机理。以高斯表面热源和圆柱体热源相结合的复合热源模型作为焊接热源, 考察了不同焊接参数下TiZrNiCuBe非晶合金在激光焊接过程中的热历史, 结合实验结果分别对接头焊缝区和热影响区显微组织变化进行了分析, 分别从加热和冷却两阶段给出非晶合金激光焊接接头非晶相得以保持的理论解释。完全非晶态接头的显微硬度测试表明: 热影响区体现出较母材以及焊缝区更高的显微硬度, 从玻璃转变温度、冷却速度以及屈服强度三者之间关系的角度对该现象进行理论分析, 并通过实验验证分析的准确性

Abstract:

Laws for temperature fields and cooling rate during laser welding have been studied by numerical simulations, in order to explore the mechanism of successful laser welding of the Ti40Zr25Ni3Cu12Be20 bulk metallic glass (BMG). Taking the effect of convection and radiation on heat transfer into account, the thermophysical properties were detected as a function of temperature. Heat source model with the cylinder and Gaussian was selected. Based on the model, the temperature fields of the Ti-based BMG at different welding parameters were calculated. Combined with the results of experiment and simulation, the microstructures from welded zone and heat affected zone have been analyzed. The mechanism of successful laser welding of Ti40Zr25Ni3Cu12Be20 BMG has been discussed from heating process and cooling process. The results obtained from the microhardness tests of completely amorphous joint indicate that the heat affected zone (HAZ) has higher hardness than those of the parent metal and weld zone (WZ). The phenomenon was studied theoretically from the relationship of glass transition temperature, cooling rate and yield strength. The experiment was also done to validate the accuracy of the analysis