S132 Spatially Resolved Strain Measurements on Micro Moulds

Abstract

The strain distribution in surface treated Toolox 44 steel was investigated using synchrotron Xray diffraction. Surface treatment involved a sequential application of grinding, micro milling and abrasive micro peening processes. The micro-features created at the milled surfaces were studied using a high lateral resolution CCD based Material X-ray Imaging (MAXIM) detector. Results from the strain measurements were evaluated with special consideration of the influence of possible geometric effects on the measured data. The sin≤ ψ method was used to determine the residual stress state at the surface of the treated samples. The results revealed that a large compressive stress component is superimposed on the ground surfaces by the milling process thus creating a stress profile different from that prior to milling. Subsequent abrasive micro peening on the previously machined surfaces removed the optically visible pattern created by the milling process and also introduced a residual stress state that is homogeneously distributed over the entire peened area. This study demonstrates the feasibility of accurately determining the strain distributions at localized features.