Hydrogen Embrittlement Failure Behavior in the Coarse‐Grained Heat‐Affected Zone of High‐Strength Ship Plate Steel

The study employs thermal desorption spectrum analysis, hydrogen microprinting technology, internal friction test, and slow strain rate tensile test, alongside microstructural characterization to examine the hydrogen embrittlement failure behavior in the coarse‐grained heat‐affected zone in welded AH36 steel. The results demonstrate that the hydrogen atoms primarily accumulated at the phase and grain boundaries and a small amount existed within the grains, leading to higher dislocation density. The internal friction spectrum of hydrogen‐charged experimental steel exhibits an H‐Snoek peak between −35 and 25 °C caused by hydrogen atom diffusion. As the hydrogen charging current density increases, the activation energies of all internal friction peaks decrease, indicating that the hydrogen atom content affects its interaction with the microstructure. As the hydrogen content in the steel increases, the crack sensitivity rate rises, and both tensile strength and elongation at break decrease significantly, indicating heightened sensitivity to hydrogen embrittlement. In addition, the fracture surface becomes flatter, and the fracture morphology shifts from ductile dimples to river patterns, signifying the transition from ductile to brittle fracture.