From anothet perspective, i was taught that metals in a non-oxidizing environment, if touching, will reform crystal bonds. So a crack deep inside a metal, if g

From anothet perspective, i was taught that metals in a non-oxidizing environment, if touching, will reform crystal bonds. So a crack deep inside a metal, if given time, can heal across a previous break. But this wound heeling will not realign complex structure, so the effect is more noticeable in non-alloy, such as a lead spline.