Effect of anisotropy of surface plastic hardening on formation of residual stresses in cylindrical samples with semicircular notch

Abstract

We study effect of anisotropy of surface plastic hardening on formation of residual stresses in solid cylindrical samples and samples with semicircular notch. Experimentally determined one and/or two components of residual stresses in a hardened layer are used as an initial information. We describe calculation method for the rest of diagonal components of residual stresses and plastic strains tensors, off-diagonal components are not considered. We propose numerical method for calculation residual stresses in semicircular notch of surface hardened cylindrical sample. This task was reduced to boundary value problem of fictitious thermoelasticity where initial (plastic) strains are modeled with temperature strains. Solution was build with the use of finite element method. We studied in detail the effect of radius of notch and anisotropy parameters of hardening on the nature and magnitude of distribution of residual stresses depending on the depth of layer in the smallest cross section of cylindrical samples of EI961 alloy steel and 45 steel. It was determined that with small radii of notch lower then thickness of hardening layer the value of axial component of residual stresses (absolute value) is higher then in the sample without a notch. Developed method was experimentally verified for samples without notches and the correspondence between calculated and experimental data was determined on distribution of axial and circumferential residual stresses depending on depth of hardening layer. For samples with notches we compare numerical solutions from this work with known solutions of other authors.

Keywords

• surface plastic hardening
• anisotropy
• cylindrical sample
• residual stresses
• semicircular notch
• boundary value problem
• finite element method