相变超塑性焊接(TSW)过程的有限元分析

相变超塑性焊接（ＴＳＷ）是一种利用超塑性流动的低应力、大变形的特殊流变规律的新型固相焊接方法。本文在弹粘塑性模型的基础上，建立了相变超塑性焊接过程的力学模型。数值模拟结果表明，对于自由边界的相变超塑性焊接接头，随着膨胀率的增大，边界上的应力将逐渐由压应力向拉应力转化；顶锻压力和循环次数既影响拉应力出现的位置，又影响拉 力数值的大小，这两个参数如何合理配合，成为影响接头质量的关键因素。对Ｑ２３５／Ｑ３５相变超塑性焊接的工艺试验研究表明，接合面中心一定范围内焊合很好，但边界上易于产生张开小口的缺陷，张口出现的位置是由界面应力决定的。

Finite Element Analysis of Transformation Super-plastic Welding

Ttransformation super-plastic welding (TSW) is an unique welding method, which takes advantage of material''s super-plastic properties of low flow stress and high plasticity. In this paper, TSW model based on elastic visco-plastic mechanics had been established. Numerical simulation results show that the stress state of border will be changed from compressive to tension within the TSW joints with free border with the increasing of expanding ratio. Not only the position of tensile stress, but also its value will be influenced by welding upsetting pressure and thermal cycles. The two parameters'' suitable matching is the key factor influencing the quality of the joint. Q235/Q235 TSW process experiments show that suflficient bonding is limited to certain scope of the middle area of joints and defect such as the opening is inclined to emerge at the edge. The results show that the position of the opening depend on the stress of the interface.