Cracked frame
 

Hello

I am posting a photo of my first frame and its catastrophic failure, in the hopes of avoiding the same mistake with the next one.

Down tube is True temper 31,8mm 0.7,0.5,0.7 HOX3TT2

The crack shape is identical on the other side of the downtube.

Any comments/observations much appreciated.

Are you the builder?

If so, it might be (just a possibility among others) the result of overheating, or overly quick cooling when brazed.

Thin walled tubing cools very quickly (by steel standards) and rapid cooling can render many alloys more brittle than otherwise.

Of course, there might be other possibilities such as stress risers from a prior non-catastrophic collision, though I see no obvious evidence of an upset.

It's hard to draw a conclusion from a photo, and often the best clues lay elsewhere, like the fork, or toptube, neither of which were shown.

Thanks for the reply, yes I'm the builder, valid point about the rapid cooling, It was welded in a semi-open shop, so even a cool breeze could make the difference I guess.

It was involved in two major collisions as well that actually bent the front disc.

Usually we see an upset (buckle or ripple) on the bottom of the tubes if a front end collision is enough to lead to this, but that isn't the case 100% of the time.

Other possible causes are misalignment when built leaving residual stress in the tube, ie. you brazed the D/T first then pulled the head in to meet a slightly short top tube. There's also the perverse irony that a thin larger diameter tube may be more prone to cracking than bending when over stressed.

Those are all possible contributing factors, but my money is on heating/cooling issues compounded by the rough service. Possibly either alone might have been OK, but the combo took it's tool.

the split is a little weird. It probably started at the edge of the heat affected zone somewhere near the bottom of the tube. Likely due to overheating. Lucky it didn't get much bigger, would have been a big boom.

That is a very ambitious material for a first frame. I would use some much thicker Verus next time