相变潜热对铍材激光钎焊熔池内流场和温度场动态行为的影响

为了能够反映固液相变过程中潜热等对熔池动态行为的影响,基于旋转高斯体热源与高斯面热源相结合的混合热源模型,分析了相变潜热对焊接熔池温度场和熔池形状的影响.计算结果表明,在铍材激光钎焊过程的温度场和流场分析中,潜热的影响不是总可以忽略的,其误差取决于材料在物相转变时交界面温差的范围及材料熔解体积的大小.与不考虑相变潜热的情况相比较,考虑相变潜热时显示出较低的最高温度、较小的熔池范围和较窄的热影响区.通过对铍材焊接温度场、焊缝断面形状模拟结果与实际热循环曲线以及焊接接头形状的对比,表明,考虑潜热的计算模型会得出更精确的结果.

Effects of Latent Heat of Phase Change on Dynamic Behavior of Fluid Flow and Heat Transfer in Laser Weld Pool of Beryllium

In order to reflect the effect of latent heat on the dynamic behavior of weld pool in process of the change of solid-liquid phase, a hybrid heat source model that based on rotary-Gauss body heat source model and Gauss area heat source was established, and the effects of latent heat of phase change on dynamic behavior of fluid flow and heat transfer in laser brazing weld pool were investigated. The results show that the effects of latent heat axe not negligible in the laser welding process and their errors depend on the temperature range during phase transformations and the size of melted material region. Compared with the analysis neglecting the latent heat, the characteristics of brazing weld pool during laser welding of beryllium is lower maximum temperature, smaller size of melting pool, and narrower heat affected zone while taking account of latent heat of phase change. The predicted weld pool geometry agrees much better with the experimental measurement while taking account of latent heat of phase change.