Can you explain this video? (An I-beam cut in half, springs apart, curved)

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The discussion centers on the phenomenon observed when a gas cutting-torch is used to split an I-beam lengthwise, resulting in the two halves flying apart due to energy release. The thermal expansion caused by the cutting torch is debated, with participants suggesting that the heat dissipates through the steel, minimizing expansion. Additionally, the conversation explores the concept of creating I-beams with flanges in tension through cold-rolling techniques, which could store significant energy. The discussion highlights the importance of material quality, specifically criticizing the use of low-cost Chinese steel that lacks proper annealing.

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A gas cutting-torch was used to split an I-beam lengthwise. When the last inch was cut, the two halves flew apart, with a great energy release. The halves are then seen to be curved where they were straight. The workman was unsurprised but the cameraman was thankful for a warning given seconds in advance.

Is this just a result of thermal expansion caused by the cutting torch? I thought most of the torch heat went with the molten iron blown away.
It was apparently cut by hand, slowly, I expect. The heat would have had time to conduct through the steel, diminishing the expansion.

Is there some technology that lets one build an iron I-beam with the flanges (flat sides) in tension? Something akin to automotive-window safety glass? I'm thinking one could cold-roll the center web lengthwise which would normally make it longer. Since it's locked to the flanges, that would put the web under compression and the flanges in tension.

You could put a LOT of energy into a spring that way and you wouldn't have to strike while the iron is hot.

Is that right? What's the roller machine called? Is there videos or literature?
Thanks.

My searches were all poisoned by steel cables used to pre-stress concrete or steel sheet cold-rolled into lightweight studs (or worst, steel cables used to pre-stress lightweight studs made by cold-rolling sheet steel)
 
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I would guess residual stress from when the beam was manufactured.
 
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It is simple to explain. Chinese steel is rolled to meet external dimensions at the lowest cost. No annealing or controlled cooling is done, so the stress of the last rolling and cooling remains in the beam. The web was thinnest, so it cooled and set first, then the thicker flanges cooled, contracting and compressing the web axially.
That is why I prefer to work with well-behaved Australian steel.

It is unusual to split an I-beam lengthwise, unless you are fabricating a castellated steel beam, but then you would not cut it straight, and you would not use cheap Chinese steel.
 
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A pity the link to the video seem to have been removed.
 
DaveC426913 said:
A pity the link to the video seem to have been removed.
The video is still there for me.
 
Baluncore said:
The video is still there for me.
Huh. This is what I get:

1707524695510.png


Anyway, thanks for posting the video.