The recently developed delayed hydrogen cracking test (DHCT) has been successfully utilized to qualitatively rank the susceptibility of various steel (G86300, K21590, K03014) to nickel alloy (N06625) dissimilar metal welds (DMWs) to hydrogen assisted cracking (HAC). This test consists of accelerated electrolytic charging with hydrogen of unnotched samples subject to a constant tensile load to replicate cathodic charging conditions that may be experienced in subsea service. The test method has proved to be sensitive to effects of welding procedure, weld sequence, and post weld heat treatment replicating the fracture morphologies of in-service DMW failures.

The current state of the test has established a methodology to develop a pass-fail criterion on which to provide a consistent quantitative measure of material/weld susceptibility to HAC. This methodology provides a link between microstructure, as influenced by material selection/combination, welding procedure, and post-weld heat treatment (PWHT), and diffusible hydrogen content.

Subject
Test methods, Corrosion failures, Materials, Composition, Diffusion, Saturation, Diffusible hydrogen, Beads, Desorption, Hydrogen charging, Steel, Hardness, Hydrogen
Keywords:
Dissimilar Metal Welds, Hydrogen Assisted Cracking, Subsea Service, Post Weld Heat Treatment, Hydrogen Charging
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2020
Association for Materials Protection and Performance (AMPP)
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