焊接残余应力对接头尘化腐蚀影响的有限元模拟

金属尘化腐蚀是发生在含碳气氛中的一种高温腐蚀现象,碳在金属基体中的扩散是其过程的第一步.文中开发了碳扩散的耦合计算程序,进行了加热炉炉管焊态和工况温度状态下焊接残余应力对碳扩散影响的数值模拟,并与无应力状态下的碳扩散情况进行了比较.结果表明,在热影响区附近焊接残余应力梯度最大,对碳扩散的影响也最大,并且形成一个碳浓度峰值,在峰值两侧则会形成相应的碳浓度低谷,这是碳向高应力梯度区扩散所致.经过升温至工况温度后,残余应力得到松弛,对碳扩散的影响有所降低,可以延缓炉管的损坏时间.但由于残余应力的影响仍然存在,因此在炉管检修期间要注意焊接接头附近的尘化腐蚀情况.

Finite element simulation on the effect of welding residual stress on the metal dusting corrosion of welded joint

Metal dusting is a phenomenon of high temperature corrosion, which occurs in carburizing environment. The first step of this corrosion is the diffusion of carbon towards metal matrix. A coupling calculating method on carbon diffusion has been developed based on the finite element program. By this method, the effect of welding residual stress on the carbon diffusion was numerically simulated for the as-welded condition and operation condition of the tube in heating furnace. The diffusion without the effect o...