Hydrogen-assisted cracking of GMA welded 960 MPa grade high-strength steels

High-strength steels with yield strength of 960 MPa are susceptible to hydrogen-assisted cracking (HAC) during welding processing. In the present paper, the implant test is used Received in revised form to study HAC in a quenched and tempered steel S960QL and a high-strength steel produced by thermo-mechanical controlled process S960MC. Welding is performed using the gas-metal arc welding process. Furthermore, diffusible hydrogen concentration (H-D) in arc A weld metal is determined. Based on the implant test results, lower critical stress (LCS) for complete fracture, critical implant stress (sigma(krit)) for crack initiation, and embrittlement index (EI) are determined. At H-D of 1.66 ml/100 g, LCS is 605 MPa and 817 MPa for S960QL and S960MC, respectively. EI is 0.30 and 0.46 for S960QL and S960MC, respectively. Fracture surfaces of S960QL show higher degradation with reduced deformation. Both, higher EI of S960MC and fractography show better resistance to HAC in the HAZ of S960MC compared to S960QL. (C) 2020 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.