Study on hydrogen enrichment in X80 steel spiral welded pipe.

Local hydrogen enrichment would increase the risk of hydrogen embrittlement in welded structures, so the dynamic hydrogen diffusion process and final concentration distribution were investigated numerically by finite element simulation for a hydrogen gas transport X80 steel spiral welded pipe. The results show that the change of microstructure induced by weld thermal cycle would decrease the hydrogen concentration in welded joint, but welding residual stress could cause local hydrogen enrichment. Equivalent hydrogen pressures for base metal, weld metal and three subregions in heat-affected zone were put forward in order to scientifically evaluate the influence of hydrogen enrichment on hydrogen embrittlement. [ABSTRACT FROM AUTHOR]