Modelling of Hydrogen Diffusion in a Weld Cold Cracking Test: Part 2, Numerical Calculations

Abstract

The purpose of this work is to compare the numerical calculation results of the hydrogen diffusion with the experimental results. We firstly conducted a y groove weld cracking test using 980 MPa grade steel and 780 MPa grade welding consumable to observe HAZ cracking. Next, we showed the present diffusion equation and the procedure to determine the physical properties for the calculations such as stress-strain curve, and using the apparent diffusion coefficient and the boundary condition obtained in the companion paper, we conducted the numerical calculations for the two cases, that is, the under-match case (980 MPa grade steel and 780 MPa grade welding consumable) and the even-match case (780 MPa grade steel and 780 MPa grade welding consumable). The calculation results of the under-match case show that hydrogen tends to accumulate in the stress concentration area of both the HAZ and the weld metal, which indicates crack may occur in both the HAZ and the weld metal. The results of the even-match case show not only the hydrogen accumulation around the stress concentration area but also high hydrogen concentration in the weld metal, which indicates crack may occur in the weld metal. Calculation results for both of the cases fairly agree with the experiments.