X-ray stress measurement of nickel-base single crystal superalloy using two-dimensional PSPC

Abstract

The stress in a single crystal of nickel-base superalloy with 72% volume fraction of γ'-phase was measured by the X-ray method. The specimen whose surface normal was parallel to [001] direction was oscillated around φ-axis during recording of the X-ray diffraction pattern with a two-dimensional position sensitive proportional counter (PSPC). The stress was determined from the measured strain using the multiple regression method and the two-tilt method. The uniaxial stress was applied along [100] direction and the stresses were measured with the X-ray methods. The stress along [100] direction, σ11, measured with the X-ray method increased proportionally to the applied uniaxial stress, and the measured stress was about 5% smaller than the applied stress. The other stress components, σ22 and σ12, did not change with the applied stress. With respect to the machined surface, the residual stress was a compression of about 700MPa on the surface and abruptly decreased to zero at about 15μm beneath the surface. The increase in the full-width at half maximum was observed within the depth of about 15μm from the machined surface. © 2007 The Society of Materials Science.