Determination of Residual Stresses in WCu Gradient Materials

Residual stress measurements were carried out on copper–tungsten gradient materials by means of neutron diffraction on the High Resolution Fourier Diffractometer on IBR-2, JINR, Dubna. The samples so far investigated had a concentration profile that approximates the gradient by step functions. The results show an averaged positive stress (stretch) in the copper phase and negative (compression) in the tungsten phase. A comparison to analytical linear elastic calculations shows that the measured values are nearly an order of magnitude too low, whereas however, a qualitative agreement of the stress distribution exists. That this quantitative discrepancy can be attributed to the model's simplifying assumption of pure elastic behaviour can be shown by recent calculations that also include plasticity and show a much better agreement with the experimental values. Single peak evaluation also strongly suggests that plasticity does indeed play a significant role.