3.4.3 Simulated environmental tests
The investigators wanted to know about the fatigue properties of the component, to find a feasible explanation of why it took 39 years for the eye bar to break. They needed information on the several stress corrosion mechanisms that were possible in the material, including hydrogen embrittlement, the effects of sulphur compounds such as H2S (hydrogen sulphide) and the effects of moisture and salt. Notched eye-bar material was loaded to failure in various environments.
In fact, no evidence emerged for hydrogen embrittlement, and a wet environment in the laboratory tests had no effect on the rate of crack propagation. However, the life of the steel samples was reduced substantially by hydrogen sulphide, a conclusion that appeared to correlate well with the detection of sulphur in the critical crack (and other, sub-critical cracks).