Shot-peening of carbonitrided steel: influence of the process on the mechanical state

¹ Université de Technologie de Troyes (UTT), ICD LASMIS, UMR CNRS 6279, 12 rue Marie Curie, BP 2060, 10010 Troyes Cedex, France
² Direction Ingénierie Process, Renault, 67 rue des bons raisins, 92508 Rueil-Malmaison, France

Abstract

Residual stresses have a significant role in affecting engineering properties of materials and shot peening process is an effective production technique to ensure required residual stress levels. This paper presents an analysis of an orthogonal design of experiment to establish an empirical relationship between main parameters of shot peening process and residual stress profiles for a carbonitrided steel. The hardening / softening evolution of the material is followed using hardness and diffraction peak width. Four critical peening parameters, i.e. shot size, incident angle, exposure time, airblast pressure, have been chosen and the range of peening conditions are established by using the Taguchi technique. In this study, a shot velocity measurement system is used to obtain the on-line velocity during the peening process and the relationship between the maximum compressive residual stresses and the shot velocity is also developed. Analysis of the experimental data showed that it is possible to optimize the shot peening process by an effective control of process parameters.