焊接熔池流体动力学行为的数值模拟和实验研究  

Simulation and experimental study on fluid dynamics behavior of welding pool and keyhole in laser welding process

作　　者：史平安[1] 万强[1] 颜怡霞[1] 沈显峰[1] 

机构地区：[1]中国工程物理研究院总体工程研究所,四川绵阳621900

出　　处：《材料热处理学报》2017年第8期134-144,共11页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(11372295);中国工程物理研究院重大基金(2013A0203008);中国工程物理研究院重点学科项目“计算固体力学”资助

摘　　要：在对激光焊接过程中匙孔壁面受力平衡状态和金属蒸发情况研究基础上,建立了随匙孔深度和形貌变化的自适应热源模型。采用Particle Level Set方法来跟踪熔池内的匙孔自由表面,对2A12合金和30CrMnSiA钢激光深熔焊过程进行了数值模拟,分析了材料性能和侧吹气体对熔池-匙孔内的温度场、流场和匙孔动态演化过程的影响。研究结果表明,相同工艺参数下热导率较小的材料,更容易形成深而窄的焊缝形貌。而侧吹气流气体的加入不仅能够改善熔池内流体的流动状态,而且能够显著地抑制焊缝中气孔产生。在此基础上,利用熔池动态监测技术对激光焊接中熔池的动态行为进行了实验观测,得到了熔池内匙孔颈缩、塌陷、闭合以及气泡的形成过程,进一步验证了模拟结果的合理性。在对不同侧吹气流下焊缝气孔检测和模拟结果分析的基础上,提出了增强焊接稳定性和降低气孔敏感性的新思路。Based on the research of metal evaporation on the keyhole wall and vapor distribution in laser welding process,an adaptive heat source model changes with keyhole depth and morphology was established.The particle level set method was used to track the free surface of the keyhole in order to analyze the flow behavior of welding pool-keyhole and the dynamical evolution process of the keyhole depth during the laser deep penetration welding of 2A12 alloy and 30 CrMnSiA steel.The influences of materials properties and side-blowing gas on the temperature field,flow field and dynamic evolution process of the welding pool and keyhole were investigated.The results show that the deep and narrow weld cross-section of the the materials with small heat conductivity can be obtained under the same conditions.The side-blowing gas can not only improve the flow pattern of the fluid in the molten pool,but also can significantly inhibit the porosity in the weld.At the same time,the dynamics behaviors of the welding molten pool in the laser welding process are observed by using dynamic monitoring technique,and the necking,collapse,closure of the keyhole in the molten pool and the bubbles formation in the simulation process are obtained,and the validity of the simulation results is confirmed.Based on the analysis of the weld porosity testing and simulation results under the different side-blowing gas flow,a new method of improving welding stability and reducing porosity sensitivity is proposed.

关 键 词：自适应热源模型 PARTICLE LEVEL SET方法 动态演化过程 流体动力学 

分 类 号：TG456.7[金属学及工艺—焊接]