(现代焊接生产技术国家重点实验室，哈尔滨工业大学 150001)
摘 要: 提出采用横向预置挤压载荷进行随焊同步防止铝合金薄板焊接热裂纹的新方法。对处于脆性温度区间的焊缝金属施加一适当的横向挤压载荷，可以减小焊缝金属凝固收缩时产生的横向拉伸应力和应变，使其总应变被限制在最低延性值范围内，改变了热裂纹产生的力学条件。建立横向预置压应力模型、采用弹塑性有限元方法阐明横向预置应力法防止热裂纹的原理，在自制的装置上对常规焊和横向预置压应力工艺条件下焊接试件裂纹率进行比较分析。鱼骨状裂纹试验结果表明：在加载宽度一定时，随着预置载荷的增加，在焊缝处产生的挤压应力也随之增加，裂纹率和裂纹长度逐渐降低，当横向预置压应力达到一定数值(0.3σ0.2)后，能够完全防止焊接热裂纹的产生。
关键字: 预置横向挤压载荷；焊接热裂纹；裂纹率；数值模拟
（National Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology,
Harbin 150001, China）
Abstract: A new technique was presented to prevent welding hot cracking of aluminum thin plate by employing transverse compressive pre-load(TCPL)during welding. A proper transverse compressive load that is applied to the weld metal in brittle temperature range (BTR) can reduce the transverse tensile stress and strain when the weld metal is contracted during its solidifying so as to limit its total strain below the minimum plastic value, and the mechanical condition of welding hot cracking is changed. The model of TCPL was established and the principle of preventing welding hot cracking was illuminated by means of elasto-plastic finite element method. The cracking rates of conventional welding and welding with transverse compressive pre-stress were compared with each other. The experimental results of fish-bone samples show that with the TCPL increasing, the compressive stress in weld increases and the cracking length and cracking rate are reduced when the load region has a given value. When TCPL reaches a certain value (0.3σ0.2), the cracking is prevented completely.
Key words: transverse pre-stress; welding hot cracking; cracking rate; numerical simulation
