How come you can bend metal back and forth and eventually break it. What is happening at a molecular level. How does movement allow for such weakening of certain metal (all metals? idk).
In: Engineering
There are two types of “bending” in metal: 1) elastic and 2) inelastic. If you bend a piece of metal elastically, it springs back and it unchanged. This is how the springs on your car hit bumps for years and never lose their springy-ness.
Inelastic bending leaves the metal “bent” afterward. This means the bonds are deformed and the atoms moved around. It also produces an effect called “work hardening”. This means that the atoms are harder to move around after they’ve been moved once. If you do this over and over, the hardened parts of the metal focus the strain on the remaining parts, which causes bonds to fail and cracks for form. As the cracks spread, the metal fails and the item breaks.
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