Delayed Cracking in Simulated Naval Platform Repair Welds

摘要

Hydrogen effusion experiments performed on standard weld samples were used to determine hydrogen diffusivity using Fickian diffusion expression and weld deposit shape. The finite difference hydrogen model was used to demonstrate the local hydrogen concentration build up and decay at the critical site for cracking in a bend specimen for two repair simulations resulting in two diffusion distances. Experimental results were compared with model prediction of the delayed cracking times. The experimental delayed cracking times for both repair simulations correspond to model predictions when the apparent diffusivity is representative of a trap density of 0.2 in the Oriani trapmodel. This trap density value was higher than the range determined from effusion experiment using a standard AWS specimen. The relative local hydrogen concentration from the model output displayed the higher hydrogen susceptibility of the single pass as-deposited weld metal when compared to the tempered weld, using the critical hydrogen curve concept.