Abstract:Seven stud bolts bending two cabins were found fractured after the separation device being static tested.
The surface of bolts was done by Dacromet treatment. Observation on fracture surface and analysis of experiment
all indicate property of delayed brittle fracture caused by hydrogen embrittlement. Besides the bolt material’ s high
susceptibility to hydrogen embrittlement, the long time wet coating on bolt during testing largely led to the fracture. Analysis
indicates that high tensile steel-made item after Dacromet coating treatment is still subject to hydrogen embrittlement
fracture that causes serious consequence under tensile stress in circumstance where water and corrosive medium
such as Cl, S exists although Dacromet coating treatment effectively prevent the item from hydrogen embrittlement
in surface processing period. This conclusion may serve as precaution to those who design and use high tensile steel
under similar circumstance.
