Subject: Re: shotpeening vs. heat treating Posted by: Cyco on December 18, 2002 at 06:50:01: In Reply to: Re: shotpeening vs. heat treating posted by Robert on December 18, 2002 at 06:23:00:

Message: >>>just out of curiosity, are shot peened parts, such as handlebars better than heat treated ones in terms of longevity? Thanks. >>Shot peening is used to relieve stress after heat treating for increase in fatigue life. That is to say, all shot peened parts are heat treated. Shot peening can also be used to make a lightweight part last as long as a heavier part (in regards to fatigue life). >Maybe, maybe not. While this is the preferred and better way to make a part, not all manufacturers will do this. And it also depends on the type and quality of the metal used, the thickness etc.. You can't give an absolute answer to a question like this without knowing the exact parts being compared and knowing either how they are made or having a large database of user results. Robert is correct here. How it each is done and the material it is done too affects the impact either will have on the life of the part. Heat treating is done to affect the crystaline structure of the material and the distribution of alloying elements in it. Shot peening increases the surface hardness of the part by localy compressing the grain structure making crack propagation more diffificult. Idealy both will be done to an amount predetermined to maximise the life of the part taking into account the material, its intended use and the manufacuuering processes used to make it.