镀锌板激光钎焊温度场的数值模拟

TEMPERATURE FILED SIMULATION OF LASER BRAZING FOR GALVANIZED STEEL SHEETS

以镀锌钢板为母材,以CuSi3焊丝为钎料,进行了单、双光束激光钎焊实验．在分析单、双光束激光填丝钎焊传热行为的基础上,采用有限元方法对激光钎焊温度场进行了数值模拟,提出了激光填丝钎焊热源模型．采用体热源来模拟熔化钎料铺展流动引起的传热,模型考虑了热物性参数随温度的变化带来的非线性影响以及潜热、辐射和对流对传热的影响．对典型激光钎焊工艺参数下的温度场进行计算,结果表明：单光束激光钎焊有较高的温度梯度,而2mm焦点间距的双光束钎焊接头峰值温度和温度梯度低,高温区域宽,更适合于获得良好的钎焊接头．

The experiments of single and dual laser beam brazing were carried out, in which the base metal is galvanized steel sheets and CuSi3 is used as filler metal. A finite element model was developed for the thermal process on the basis of heating behaviors analysis, and the transient temperature fields in the braze joint were calculated. In the model, the surface heat source was used to model laser heating the surface of filler metal and base metal, and the heat transfer induced by the flow of melted feller metal was simulated by a volume heat source. Nonlinear effect of temperature on thermal properties, latent heat, the convection and irradiative heat losses were considered. Numerical results of the temperature fields in the braze joint were obtained for typical process parameters. The results show that the temperature gradient of individual beam brazing is high, however, in dual laser beam brazing with 2 mm spot distance, the peak temperature and temperature gradient are low and high-temperature zone is wide, which is benefit to achieve good brazing quality.