How Thermite turned the clickety-clack of railroads into seamless, silent tracks. Get an exclusive 15% discount on Saily data plans! Use code veritasium at checkout. Download Saily app or go to https://saily.com/veritasium
A massive thank you to everyone at Goldschmidt for making this possible. With special thanks to Dr. Axel Hoeschen, Christof Gassmann and Claudia Koch.

If you want to learn all the details about why we don’t need expansion joints anymore, check out Grady’s excellent video here: • Why Railroads Don’t Need Expansion Jo…

If you’re looking for a molecular modeling kit, try Snatoms, a kit I invented where the atoms snap together magnetically. https://snatoms.com/

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00:00 The problem with continuous welded rail
03:33 How to weld two rails together
10:16 Why is rapidly cooled steel brittle?
11:40 Thermite reaction and a see-through mold
16:30 Clean up
19:11 Metallurgy
22:15 How strong is the weld?
24:26 Why don’t the rails buckle?

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References:
Practical Engineering. Why Railroads Don’t Need Expansion Joints • Why Railroads Don’t Need Expansion Jo…
Stress–strain curve In Wikipedia – https://ve42.co/stressstrain
The Efficient Engineer. Understanding Metals via Youtube • Understanding Metals
moodlemech. Properties and Grain Structure via Youtube – • Properties and Grain Structure

Images & Video:
bhadeshi123. Martensitic transformation via Youtube • Martensitic transformation
Stratford Works In Wikipedia – https://ve42.co/stratford
Electric Tram 1881 In Wikipedia – https://ve42.co/tram
Water Quenched Steel In Wikipedia – https://ve42.co/quench
Synagoge 1922 In Wikipedia – https://ve42.co/synagoge

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