焊接热循环过程中氢陷阱热释放的数值分析

Numerical analysis of hydrogen traps thermal desorption in weld thermal cycle

基于焊接热循环过程的特点,分别提出了热循环的升温段和冷却段过程中氢陷阱的热释放的动力学模型,并运用数值分析的方法,对焊接热循环中氢陷阱的热释放过程进行了研究.结果表明,高强度低合金钢的多层多道焊中,前一焊道受后续焊道的热循环作用下,焊道中的氢陷阱存在热释放过程,且弱氢陷阱在热循环的升温段就基本完全被释放出去,而稳定性较强的强氢陷阱在整个热循环中只有少量的氢被释放;热循环的层间温度、峰值温度和冷却时间的增加都会使陷阱的氢释放比率有相应的增加,而加热速度的增加,陷阱的氢释放比率下降.氢陷阱在焊接热循环中的氢释放过程,经分析对多层多道焊的焊缝去氢作用明显,可以有效的降低焊缝发生氢致裂纹的风险.

Based on the characters of weld thermal cycle,the hydrogen traps thermal desorption model is founded and studied by using the numerical analysis.The results indicated that the hydrogen traps have the process of thermal desorption when the previous weld bead is heat treated by the latter bead in the HSLA steel multilayer and multipass welding process,and all of hydrogen in weak traps has almost been desorbed in the heating time section,but the hydrogen in strong traps has only little been desorbed in all the time of weld thermal cycle.The hydrogen traps thermal desorption proportion will increase when the parameters of interpass temperature,peak temperature and cooling time increase in weld thermal cycle,but it will decrease when the parameter of heating rate increase.The process of hydrogen traps thermal desorption is useful to dehydrogenate in HSLA steel multilayer and multipass welding,and it can effectively decrease the probability of hydrogen induced crack.