Some people think they can tell if a part broke due to hydrogen embrittlement by looking at it. This is not correct. The timing of the crack is only one of the key factors that needs to be documented if hydrogen embrittlement is suspected. Four more will be listed in this blog series. 

While it is possible that hydrogen embrittlement can be associated with immediate fracture on install, it would be surprising if there were no additional factors that facilitated such a rapid hydrogen-assisted damage event. Perhaps a quench crack, or a forming or casting discontinuity, concentrated the stresses beyond the design plan. Suspicion is warranted when reviewing reports that diagnose hydrogen without reporting the timing of the crack event(s). 

All five of the listed parameters must be documented for a credible diagnosis of hydrogen embrittlement in hardened steel components. Note that there are other sources of hydrogen aside from pickling and plating. It is also important to realize that intergranular cracks may look very different in components that have experienced heavy cold work without additional high-temperature exposure. 

Fig. 1. Scanning electron micrograph, originally captured at 150x, showing typical intergranular fracture for steel hardened by heat treating and then embrittled with hydrogen.