Measurement And Numerical Simulation Of Quenching Residual Stress In 7055 Aluminum Alloy Thick Plate

7055 aluminum alloy is one of Al-Zn-Mg-Cu series wrought aluminum alloy that can be strengthened by heat treatment, 7055 aluminum alloy thick plate is widely used in the field of manufacturing aerospace and other important structures in the international with its ultra high strength and excellent comprehensive performance. The 7055 aluminum alloy thick plate deforms easily and even cracks in the process of aviation users because of large residual stress. Quenching residual stress is the original residual stress in the thick plate. In this paper, the distribution of quenching residual stress in the 7055 aluminum alloy thick plate was researched by experimental measurement and numerical simulation. This work provides the experimental basis for the optimization of the industrial production process and the research work has practical value and theoretical significance.The reliability of surface quenching residual stress measuring method of 7055 aluminum alloy plate was research by comparing the X-ray diffraction method and hole-drilling method. Comparing with the X-ray diffraction method, the hole-drilling method has better stability and is suit for the surface residual stress measurement in the 7055 aluminum alloy plate.Crack compliance method is applied to measure the distribution of quenching residual stress through thickness in the 7055 aluminum alloy plate. The results show that the rolling component and the transverse component of quenching residual stress have similar distribution through thickness. The compressive stress exists on the surface while the tensile stress exists in the center. The maximum rolling component residual stress is-110 MPa and transverse component residual stress is-140 MPa on the surface, while the maximum rolling component residual stress is 130 MPa and transverse component residual stress is 115 MPa in the center.The surface quenching residual stresses in the 7055 aluminum alloy thick plate in different quenching parameters(quenching medium temperature, concentration and species) were measured and evaluated by using hole-drilling method systematically. The cooling capacity order of quenching medium on alloys is 15%PAG<10%PAG<5%PAG< water<10%Na Cl in 20℃. With the increasing of water temperature or PAG solution concentration, the quenching residual stress decreases. When the water temperature increases from 20 oC to 80 oC, the rolling component residual stress decreases from-187.1MPa to-88.0MPa, while the transverse component residual stress decreases from-225.7MPa to-45.3MPa, thus the quenching residual stress decreases by 50%. Comparing with 5% PAG solution, 15% PAG solution leads to a decrease of rolling component residual stress for 52.2% and transverse component residual stress for 47.2%. Comparing with the performance of thick plate with T6 temper, the thick plate of 10%Na Cl solution quenching treatment has the highest strength performance, but it has the highest level of quenching residual stress; after 15%PAG solution quenching treatment, the residual stress level of thick plate decreases significantly, but the strength is lower than the former of 22.9MPa.Through measuring the physical and other properties of 7055 aluminum alloy plate, the finite element model was established and the distribution of quenching residual stress in 7055 aluminum alloy thick plate was researched by numerical simulation. The surface quenching residual stress is compressive while the center quenching residual stress is tensile in the 7055 aluminum alloy thick plate. The measurement results are in agreement with the predicted results. The effect of thickness on quenching residual stress is investigated, and the quenching residual stress increases obviously with the increasing plate thickness. When the plate thickness increases over 80 mm, the growth rate of quenching residual stress gradually decreases.