Distribution of residual macrostresses arising in process of surface plastic deformation of steel parts

Abstract

As is well known, with surface plastic deformation of articles (rolling with rollers or a ball, stamping, blasting with shot, etc.) there arise residual compressive stresses, characterized mainly by two kinds of diagrams: the first with a maximum of the compressive stresses at the surface and the second with a drop in these stresses near the surface. In the first case, the stress distribution is considered more favorable for an increase in the fatigue strength. There are different opinions as to the reason for the appearance of two kinds of diagrams. Many investigators have come to the conclusion that the drop in the stresses is the result of the effect of the temperature, arising in the deformation process [1-3]; some explain this drop by the existence of different deformation schemes: contactshear and pure contact [4]. For example, with rolling by a ball there is a purely contact scheme of the deformation, and with rolling by a roller there is contact-shear deformation. The authors of [5] explain the drop in the residual stresses by a different scheme of surface plastic deformation, in accordance with which the second kind of diagram must occur more frequently for peripheral stresses than for axial stresses. However, it is not clear why under identical conditions for one steel there is a drop in the stresses, while for another steel there is not.