i was watching the speed channel one day on ARP products, and they said shot peening is done to get rid of slag buildup on metals after they have been heat treated. so i came up with this: most people i've seen on tech boards shot peen their rods (thinking that it adds strength?) and they dont mention that they heat treated them first. so i'm thinking that shot peening doesnt strengthen the metal cause it's the heat treating that strengthens the metals?

are these people just wasting their money?
Can someone clarify this so i can just forget about it?

 

Heat treating the metal on a rod for example will make the metal harder, but less flexible. There may soon be small cracks appearing. Thus, heat treatment may actually make the rod more brittle.

Shotpeening will do the opposite. It will make the surface of the metal denser, because of the small beads hitting hard and compacting harder the molecules. This only happens on the surface. The inside part of the rod will not be affected, thus remaining at the same level of porosity and flexibility.

You got the choice between shotpeening and heat treatment? Definitely go with shotpeening. Your rods will take the extra beating much better, and much longer.

 

When you get the rods, they have already been heat treated. The shot peen is a stress relief to help stop stress cracks that would lead to rod failure.