Hydrogen embrittlement — a bolt, and what is inside it

Drag the drawing upward to load the joint, then let go and watch — the load stays on. Drag sideways to turn the bolt over; the arrow keys do the same. Home lets the load off, End takes it straight to a hard pull. The sound toggle is part of the piece.

This is an interactive demonstration of hydrogen embrittlement, and it needs JavaScript to run. What it shows: a high-strength bolt can absorb hydrogen during plating, and under sustained load that hydrogen gathers at the first engaged thread — completely invisibly, with the bolt passing any visual inspection — until the bolt breaks without warning. Resting the part does undo the concentration, but far too slowly to be any use in production, which is why suspect parts are baked in an oven instead. Nothing about the part's appearance ever changes before the break: that is the point, and it is why this page is a demonstration rather than a picture.

What is not verified

Stated plainly, because a piece whose value is trustworthiness should not overclaim. The first list is the part that would change how you read the result. The second is scope — true, worth saying, and not load-bearing.

No engineer has reviewed the physics. The proportions were checked against ISO metric coarse practice — ISO 68-1, 4014, 4032, 7089/7092 and 273 — and against ASTM B850 and F1940 for baking practice, and the joint mechanics hold up. But that check was the author's own. Before this is relied on as authority, it wants a metallurgist's eye.
The baked bolt keeps a number I chose, not a number I measured. A baked part is built holding fourteen per cent of the original charge. That is not a residual from a diffusion calculation — there is no diffusivity in this file and no model of egress against time. It is a display value, picked to sit under the bound below which the demo is arithmetically unable to show a fracture, so that the piece cannot kill a bolt the oven saved. ASTM B850 and F1940 are cited for baking practice, not for that fraction. If you want to know what a real bake leaves behind, this page is not evidence, and quoting the figure back as though it were would be worse than quoting nothing.

Scope, for completeness. True of the model, and none of it changes the answer above.

The sound path is measured on one browser engine (Chromium). The audio is opt-in and the piece is complete without it.
The frame budget is measured in a software rasteriser, which is slower than the integrated graphics this targets — so those numbers are a floor, not a forecast.

Commissions

The subject changes; the method does not. If you have a failure mode, a mechanism, or a process that people keep getting wrong because the diagram cannot move, that is the shape of problem this suits. You get one file, the checks that hold it honest, and the notes explaining every decision including the ones that were reversed. Commissions start at £4,000 and take three to four weeks from an agreed brief. yinxueshi1017@gmail.com

Not commissioning anything? Still worth an email. If your version of this failed differently — other geometry, other numbers, a mechanism this piece leaves out — tell me in one line. Corrections are the main thing that decides what gets built next.