## 1 Introduction
[PERSON] [27] determined the through-thickness residual stress distribution of turbine discs during the isothermal forging, solution treatment and aging treatment using neutron diffraction and 2D-detector X-ray diffraction. The results demonstrated that residual stress exhibited typical thermal stress distribution while plastic deformation-induced surface stress was relieved after the solution and aging treatment. [PERSON] [28] investigated the effects of aging temperatures and aging times on the amount of residual stress relief for Al-Cu forged blocks after aging treatments by a numerical simulation method and experimental measurements. The peak-aged (T6) and over-aged (T7) condition produced only about a 22.5 to 34.7% reduction in residual stresses. [PERSON] [29] used neutron diffraction to in situ follow the evolution of residual stress of Inconel 718 during the aging process. Almost 90% of stress relaxation was found to occur primarily during heating to the aging temperature as a result of a combination of plasticity and early-stage creep relaxation. A novel multi-stage interrupted artificial aging treatment [30] was designed for reducing residual stresses in quenched Al-Zn-Mg-Cu alloy thick plates. The results showed that residual stress magnitudes were reduced significantly and even eliminated completely by this novel treatment while the conventional artificial aging only contributed to a reduction of 10-35%, because an inverse stress was ingeniously employed during rapid heating to release the internal residual stress. [PERSON] [31] studied the residual stress relaxation and the texture evolution of cold-rolled AZ31 Mg alloys using the vibratory stress relief technique. It can be seen that the uniform surface residual stress distribution and relaxation of the compressive residual stress in the stress concentration zone were observed rather than all of the residual stresses being eliminated. In addition, with an increase in the vibrational aging time, the compressive residual stress, texture density and (0002) preferred orientation increased first and then decreased. However, much previously published research focused on the variation of residual stress during a single stage, such as quenching, cold deformation or aging. Cold deformation and the aging processes both played a vital role in the reduction of residual stress; however, the contribution of these two processes on the stress relief has not been extensively investigated. In addition, the effects of cold deformation and the subsequent aging on the distribution of residual stress need to be further analyzed, especially for the components with unique geometry. In this study, a T-type rib was adopted, and numerical models were established to investigate the evolution and distribution of residual stress during the quenching and cold pressing processes. Then, three comparative T-type ribs were conducted, which were quenched, quenched-cold pressed and quenched-cold pressedaged, and the distribution of residual stress was measured using X-ray diffraction and the contour method.. Finally, the mechanism of the stress reduction during the cold pressing and the aging processes was discussed.