Derating is not a good option for dealing with hydrigen embrittlement due to the unpredictability of potnetial failure. The problem must be controlled/eliminted in process. I know of circumstance in which a critical flight control component fialed due to hydrogen embrittlement under strictly vibratory loading - no compression or tensile load at all. Reuslt was the death of a number of individuals.
Well, hydrogen embrittlement is a long known issue that has played havoc with metals at nuclear power plants and has lead to fuel rod cadding failures along with reduction of the rating of some containment vessels.
@TJ McDermott: I would strongly recommend against derating hydrogen embrittled parts, if by derating you mean using the affected parts in a lower-stress application. The problem is that it's extremely difficult to predict what level of stress a hydrogen-embrittled part will fail at. Even residual stresses from the forming process may be enough to produce microcracks, which may propagate later in fatigue. If I knew that a part was likely to be hydrogen embrittled, I wouldn't recommend using it in any application.
The same line of argument applies to baking parts as a re-work method after a problem has been found. As I mentioned, it's important to bake parts as soon as possible after plating or welding. Some aerospace specifications require that this be done within one hour. The more time passes, the less effective baking will be. This is not so much due to the hydrogen being any more difficult to remove (although you will hear this claim), so much as the fact that microcracks may have already formed as a result of residual stress. Obviously, once cracks have formed, no amount of baking will heal them.
As naperlou pointed out, prevention of process-induced hydrogen embrittlement depends on having a good quality system in place. If you're plating or welding high-strength parts, you need to ensure that they are always baked at the proper temperature within the specified length of time.
This is an interesting example of a failure mode that is not going to be easy to predict. It seems that, short of testing a sample of the parts after each process, one can only track the parts after production and remedy situations as they occur. This requires a detailed tracking of the products after delivery and detailed reports of problems. In general, quality control systems do this. By linking those databases with design data in a PLM system, another big theme of Design News lately, one can avoid the problem in the future.
With erupting concern over police brutality, law enforcement agencies are turning to body-worn cameras to collect evidence and protect police and suspects. But how do they work? And are they even really effective?
A half century ago, cars were still built by people, not robots. Even on some of the country’s longest assembly lines, human workers installed windows, doors, hoods, engines, windshields, and batteries, with no robotic aid.
DuPont's Hytrel elastomer long used in automotive applications has been used to improve the way marine mooring lines are connected to things like fish farms, oil & gas installations, buoys, and wave energy devices. The new bellow design of the Dynamic Tethers wave protection system acts like a shock absorber, reducing peak loads as much as 70%.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.