金属尘化腐蚀层内应力的有限元模拟计算

Finite element simulation for internal stress of metal dusting corrosion layer

通过低合金Cr5Mo在600℃,H2-CO混合气氛中的尘化腐蚀试验,得到碳在Cr5Mo中的扩散系数,在此基础上,利用大型有限元软件ABAQUS及其自编用户子程序(USDFLD,UEXPAN和UDIFF),开发了热-弹-塑-扩散耦合计算程序,对Cr5Mo尘化腐蚀层内应力进行了有限元模拟,并与不考虑扩散应力的内应力进行了比较.研究结果表明:Cr5Mo在尘化腐蚀过程中因碳的扩散而引起的扩散应力水平比较高;高应力区主要集中在腐蚀层表面和腐蚀层/基体界面处;扩散应力在最终的尘化腐蚀层内应力中占有相对比较大的比重,是导致腐蚀层开裂和剥落的重要原因之一.

Based on the carbon diffusivity obtained from the metal dusting corrosion experiment of Cr5Mo at 600 ℃ in H2/CO mixture gas,a coupling calculation method for thermal-elastic-plastic-diffusion has been developed with ABAQUS finite element code and its user subroutines of USDFLD,UEXPAN and UDIFF. According to this method,the internal stress of metal dusting corrosion layer for Cr5Mo was simulated and compared with that without consideration of diffusion-induced stress. The results show that the carbon diffusion-induced stress during the process of metal dusting is in a higher level. The surface of metal dusting corrosion layer and the interface between this layer and base material are the main high stress zone. The diffusion-induced stress possesses a high percent in the final internal stress of metal dusting corrosion layer. And it is one important reason to cause the metal dusting corrosion layer broken.