Sulphide stress cracking behaviour of the coarse-grained heat-affected zone in X100 pipeline steel under different heat inputs

The sulphide stress cracking (SSC) behaviour of a simulated coarse-grained heat-affected zone was investigated under different heat inputs. The microstructure and fracture surfaces were observed. SSC susceptibility was dominated by hydrogen embrittlement (HE) and, to a lesser extent, anodic corrosion. Heat input had a critical effect on the microstructure and material properties. When t(8/5) (time taken to cool from 800 degrees C to 500 degrees C) was 30 s, the microstructure was mixed lath bainite/granular, with low HE and high SSC resistance. When t(8/5) was 100 s, the microstructure was granular bainite, with high corrosion current density and low SSC resistance. The results provide guidance for development of SCC resistant welding procedures. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.