eli5 How does razor blade dull on hairs when razor blades are made of steel and they are much higher on mohs scale?

Question

eli5 How does razor blade dull on hairs when razor blades are made of steel and they are much higher on mohs scale?

In: 4692

Answer 1

At really tiny scale a blade can have defects. Even with hair being soft compared to a blade, at that scale the force exerted on the blade can cause it to bend. This introduces something called stress intensification.

Defect will cause the bending to chip, and those chip is what dulls the blade.

For rusting, those are also defects that can directly contribute to the dulling, but has nothing to do with hair