Effect of residual stress on wear of hole surfaces

Abstract

In this study, pre-machined holes were strain-hardened by means of ballising where a hardened precision ball was forced through slightly undersized holes. Rochling T4 steel in the as-delivered, spheroidised and normalised conditions were employed. Wear tests, in the direction parallel to the axis of the hole were conducted on the ballised hole surfaces. The level of wear improvement was found to be dependent on the interaction of a number of parameters such as wear mode, percentage interference between the ball and the pre-machined hole, and mechanical properties of the test material. The level of wear resistance was at its highest when a 2% hole interference was applied and the strain-hardened surfaces subjected to axial wear mode using materials in the as-delivered and spheroidised conditions. For the normalised material, the highest wear resistance level was achieved with a 3% hole interference under radial wear mode. Although normalising increased the hardness of the material, it was not able to bring about a better wear benefit than material in the as-delivered condition. Spheroidisation was found to result in greater plastic deformation but produced the poorest wear resistance.