多束流电子束薄板焊接应力变形数值模拟

为了减小薄板结构的焊接变形，基于电子束高频偏转扫描技术在焊缝两侧添加辅助扫描热源实现了多束流电子束焊接及焊前预热. 建立了矩形均匀加热辅助热源模型，采用热弹塑性有限元分析方法对1.5 mm厚304不锈钢薄板进行多束流电子束焊接数值模拟，并进行了试验验证. 结果表明，焊后残余应力和变形的实测结果与模拟结果吻合良好，多束流电子束焊接方法不仅可以改变熔池前方材料的受力状态，而且可以减小熔池形成瞬间熔池前方材料的压应力峰值，有利于减小熔池的前方压缩塑性应变，进而减小薄板结构的焊接变形.

Numerical simulation of thin plates on welding stress and distortion of EBW with multi-beam

Electron beam welding (EBW) with multi-beam method that employs the main beam for welding and two other beams for pre-heating the material regions simultaneously on both sides of the welding seam from a certain distance was proposed for mitigation of welding distortions of thin plates. The uniform rectangular assistant heating source model was established. The numerical simulation of EBW with multi-beam for 1.5 mm thick 304 stainless steel sheet by the thermo-elastoplastic finite element analysis (FEM) method and corresponding experimental test was carried out. The results showed that the simulation values of welding residual stresses and distortions were accordant with the measured values well. EBW with multi-beam can change the stress state of the materials located in front of the molten pool and reduce the peak value of compressive stress of the same position at the moment of molten pool formation, which can effectively reduce the compressive plastic strain, so as to decrease the welding distortion of thin plate.