Assessment of residual stress of 7050-T7452 aluminum alloy forging using the contour method

Through Thickness Residual Stress and Microstructural Mapping of AA7085-T7452 Die Forging

“…These results differ from the trends observed in the present work, the sample size and the extent of deformation and the thermal gradients could determine the actual trend observed. The through-thickness hardness and through thick residual stress appeared to follow the same trend in their work [5], and a similar trend is also seen in this work (Fig. 2).…”

“…The mean error or uncertainty in the XRD residual stress measurements was 7.5 MPa and the range was 4 to 12 MPa. This kind of variations in the residual stresses measured has also been reported in the literature [5]. The longitudinal residual stresses in the cold compressed forging were reported to vary with the position along the length of the forging due to multiple compression and overlap [3], during post-quench cold compression stress relief [5].…”

“…Also note the differences in the hardness results for B3 which is at the centre (core) of the forging; the short transverse hardness is lower than the longitudinal hardness, an indication of the inhomogeneity present in the thick forging. Zhang et al [5], examined the through-thickness hardness distribution in the centre of the specimen in a 121 mm thick 7050-T7452 forging and a minimum value of hardness occurred at one end of the specimen near the surface, corresponding to a low value of tensile or compressive residual stress and a maximum hardness at the centre of the specimen. These results differ from the trends observed in the present work, the sample size and the extent of deformation and the thermal gradients could determine the actual trend observed.…”

“…The observed trends in Figure 2 for the measured residual stresses (slitting) and the short transverse surface hardness are more closely aligned suggesting a potential intrinsic relationship between the two parameters. Zhang et al [5] commented that the through thickness residual stress profiles and the spatial variation in stress distribution are likely to have been caused by the non-uniform plastic deformation during the stress relief treatment.…”

“…The mechanical stress relief treatment by cold compression (forgings) or stretching (rolled plate) that follows, aims to relieve (or reduce) the severity of the bulk residual stresses existed in the asquenched state in the component. However, cold compression stress relief in die forged components do not always fully relieve the complex 3 D bulk residual stresses, and the unrelieved residual stresses may be of sufficient magnitude to cause distortion in machined components [4][5][6]. Moreover, the three dimensional residual stress distribution in the stress relieved aluminium die forging varied…”