Finite Element Simulation and Experimental Verification of Internal Stress of Quenched AISI 4140 Cylinders
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THE AISI 4140 medium carbon steel has been widely used to cylindrical components by quenching and tempering in engineering.[1] The mechanical properties of steel components can be improved markedly by the quenching and subsequently tempering process. However, there are also several problems in the quenching process, such as distortion and cracking caused by internal stress. Internal stress is caused by nonuniform cooling and phase transformation at different locations of a component. It is vital to know the internal stress distribution and transient stress histories during quenching in the design of the quenching process. The measurement of the internal stress distribution in a quenched component along depth is necessary as the base of the design of the quenching process. However, experimental measurement has two main limitations. (1) For a component with large scale and complex shape, the measurement of the internal stress along depth is not only difficult but also time-consuming. (2) In most cases, the cracking of a quenched component is caused by transient stress during quenching, while experiment can only measure the final internal stress (residual stress), rather than transient stress. For these reasons, the computer simulation of quenching was developed to predict the temperature, phase, and stress evolution so YU LIU, SHENGWEI QIN, QINGGUO HAO, XUNWEI ZUO, and YONGHUA RONG are with the School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P.R. China. NAILU CHEN is with the Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, P.R. China. Contact e-mail: [email protected] Manuscript submitted May 23, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS A
as to optimize the quenching process.[2,3] S¸ims¸ir and Gu¨r[4] used a three-dimensional (3D) finite element method-based model to predict temperature history, evolution of microstructure, and internal stresses of eccentrically drilled C60 steel cylinders during quenching, and the comparison with experimental results indicates that the model can effectively predict the trends in the distribution of residual stresses for 3D asymmetric components. Jung et al.[5] proposed a new method for determining variables: the start temperature of bainitic transformation (Bs), and the start temperature of martensitic transformation (Ms), the accuracy of the simulated residual stress was improved. Lee and Lee[6] suggested a new calculation method of Ms and kinetics equations of diffusive and diffusionless transformations. Ariza et al.[7] predicted the residual stresses of carbon and low-alloy steels, and the predicted results correspond well with the X-ray diffraction (XRD) measurement results. Although computer simulation of heat treatment has been developed rapidly in recent years, and many commercial software products, such as HEARTS,[2] SYSWELD,[8] DANTE,[9] COSMAP,[10] and [11] are available in the market, there DEFORM-HT, are still so
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