Characteristics of Residual Stress Profiles in Spring Steel Induced by Stress Rolling

Stress peening is a modern technique to enhance the durability of spring. The springs are shot peened under prestress, and after unloading, the residual stress will increase significantly. The same procedure can also be done by deep rolling. The difference is that deep rolling has two different residual stress directions (amounts) if you look along or perpendicular to the rolling track. Therefore, you get in sum four totally different residual stress distributions if you take into consideration that the prestress (before rolling) is along or perpendicular to the track. The residual stress distributions in the dependence of the above-explained facts, and different prestresses are investigated. The different depths of the interaction zones are shown. Also, the limit of the theoretical inducible residual stresses is compared with the experimental results. Last, but not least, a practical application of a torsion bar is presented.