Influence of Manufacturing Processes on the Selection of Stress Measurement Techniques

Author:  M. Belassel, J. Pineault, M. Brauss
Source:  ICSP-13
Doc ID:  2017082
Year of Publication:  2017
Introduction: Residual stress (RS) measurements performed using x-ray diffraction (XRD) techniques have been widely applied to numerous materials subject to various manufacturing processes, such as machining, shot peening,heat treatment, etc. A variety of XRD techniques and associated methodologies can be applied to measure RS including: a) the multiple exposure technique (MET) in both psi and omega modes, b) the single exposure technique (SET) or double exposure technique (DET). The SET has disadvantages, many of which are well known to engineers and scientists when applied to materials subject to induced shear stress. However, in practice the appropriate technique is not always selected in the context of the manufacturing process that is being evaluated. This paper will bring to light many of the insufficiencies and commonly misunderstood issues related to XRD based RS measurements by comparing the SET and MET, as well as proposing corrective measures and best practices as deemed applicable with the goal of collecting data and results of superior quality. A variety of materials subject to different cold working processes were selected where both the SET and MET were compared with the purpose of evaluating the efficacy of each and to identify any weaknesses in either when performing RS measurements on real hardware. The results obtained indicate that surface and subsurface RS measurement data collected using the SET is in most cases misleading and erroneous and that the MET is a much more reliable measurement technique.

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