Influences of Ribs on the Residual Stress and Deformation of Long Stringer Aluminum Alloy Forgings During Quenching
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JMEPEG https://doi.org/10.1007/s11665-018-3600-7
Influences of Ribs on the Residual Stress and Deformation of Long Stringer Aluminum Alloy Forgings During Quenching Xingang Liu, Danqing Wang
, Ning Liang, Wentao Shen, Peng Zhang, and Baofeng Guo
(Submitted February 27, 2018; in revised form July 20, 2018) To improve the mechanical properties of aluminum alloy forgings, solution treatment and quenching is necessary. However, it becomes difficult to control the residual stress and deformation after solution treatment and quenching which always results in obtaining a part with an undesirable size, especially for a long stringer forging with an existing rib. Therefore, this paper demonstrates a quenching experiment and residual stress measurements for a ribbed aluminum alloy forging; the calculated results are close to the actual convective heat transfer coefficients. In addition, the heat transfer coefficient is introduced into the quenching simulation of a long stringer forging consisting of rib-web forging and plate forging. The influence of ribs on the residual stress and deformation of the forging is compared and analyzed. The results show that the heat transfer coefficient on the web without a rib is highest and the heat transfer coefficient on the web below the rib is lowest. Compared with the plate forging, the deformation direction of the rib-web forging is opposite, and the deformation of the rib-web forging is obviously increased. Keywords
aluminum alloy, deformation, forging quenching, residual stresses
1. Introduction Aluminum alloys are important materials for manufacturing aircrafts. Aluminum alloys also represent the highest proportion of the materials employed in the main commercial aircraft manufacturing industry at present (Ref 1). Aluminum alloys, especially the 7xxx series of aluminum alloys, which have advantages of high strength and good corrosion resistance, are used to manufacture upper wing skins, stringers and other important parts of aircraft structures (Ref 2). The performance advantages of the 7050 aluminum alloy mainly rely on a reasonable distribution of MgZn2 precipitates, which depends on the solutionizing and aging (Ref 3, 4). Poor control of the quenching process for larger 7050 aluminum alloy forgings will not only affect the performance characteristics of the final product in use but also cause the forging process to produce large residual stresses, which lead to difficulties in controlling the shape of forgings during heat treatment and subsequent cold working (Ref 5, 6). Therefore, predictions of the temperature and stress fields and deformation have become a popular topic of research related to the process of quenching aluminum alloy forgings (Ref 7, 8). In particular, given the aluminum construction materials used in large-scale aircraft manufacturing, the problem has become increasingly prominent. Xingang Liu, Danqing Wang, Ning Liang, and Baofeng Guo, Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education, Yanshan University, Qinhuangdao, Ch
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