固态相变对P91钢焊接残余应力的影响

Investgation of influence of solid-state phase transformation on welding residual stress in P91steel joint

关键词:  P91钢  固态相变  焊接残余应力  数值模拟

Key words:  P91  solid-state phase transformation  welding residual stress  numerical simulation

摘要:

基于SYSWELD软件,首先模拟了P91的Satoh试验,得到加热、冷却过程中的温度-应力曲线. 通过Satoh试验探讨了因固态相变引起的体积变化、屈服强度的变化和相变过程中的超塑性对残余应力形成过程的影响. 随后,以平板TIG重熔模型为研究对象,系统讨论了固态相变对焊接残余应力分布和大小的影响. 结果表明,体积膨胀对焊接残余应力的形成过程和最终应力的大小与分布有显著影响,它不仅可改变焊缝及HAZ处的应力大小,甚至可能改变应力的符号. 相变引起的屈服强度变化对残余应力的形成及最终应力值的大小也有较明显的影响. 相变塑性的影响比前两者小,它在相变过程中有一定的"应力松弛"效应.

Abstract:

Based on SYSWELD software, Satoh Test of 9Cr-1Mo steel was simulated and the temperature-stress curves under different conditions were obtained. Using the simulated results, we discussed the influence of volume change, yield strength variation and phase transformation induced plasticity (TRIP) on the formation of residual stress. Meanwhile, the welding residual stresses induced by TIG welding process in 9Cr-1Mo steel joint was simulated using the developed computational approach. Simulation results show that volume change during austenite-martensite phase transformation has a significant influence on the formation of welding residual stresses, and it not only changes the magnitudes of residual stress but also even can alter the sign of residual stress. Yield strength variation also has certain influence on welding residual stresses. Comparing with volume change and yield strength variation, TRIP seems has less influence on welding residual stress, however, it can relax stresses during phase transformation in the fusion zone and the heat-affected zone.