Wear Resistance / Fatigue strength
Most mechanical parts have to go through processes that giving a good result in wear resistance and fatigue resistance because they must work under force, abrasion or being crushed all the time. The wear of material is caused by the movement or sliding of parts with solid, liquid or gas.
While fatigue of material is caused by repeated forces and stress, until parts have fatigue in material and when the continuous force is applied, parts will eventually break down, affecting the work of parts, such as engine that has to work all the time, vibration of spring, etc.