Papers by Author: Jian Wei Zhang

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Authors: Xiao Bo Liang, Shi Qiong Li, Yun Jun Cheng, Jian Wei Zhang
Abstract: The characteristics of deformation of an orthorhombic phase based alloy, Ti-22Al-25Nb (at%), have been studied by hot compression tests in the temperature range of 940-1150°C with the strain rates of 0.01s-1 and 0.1s-1. A flow curves typically controlled by dynamic recovery were observed in the temperature range of 1090-1150 °C for the strain rate of 0.01s-1 , while discontinuous yield phenomena was found for the strain rate of 0.1s-1. The dynamic recovery can be identified by the microstructure characteristics of the deformation specimens. At 1060°C, the temperature of beta transus, the flow curves and microstructure exhibited the same deformation charateristics as that above the beta transus. At the subtransus temperature, a long period of flow softening followed by the steady-state flow can be observed. During the hot deformation, the hard phases α2 and O elongated, subboundary produced followed by cusp formation in the elongated α2 and O phases, the equiaxed morphology phases occurred by B2 phase penetrating along the subboundaries. The softening mechanism was discussed.
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Authors: Shi Qiong Li, Yun Jun Cheng, Xiao Bo Liang, Jian Wei Zhang
Abstract: Ti2AlNb orthorhombic phase based alloys are the promising high temperature structural materials for aeronautical and aerospace industry because of their low density, high yield strength and excellent high temperature performance. In this paper, the recent work which has been carried out in CISRI on alloy and process of Ti2AlNb based alloys is presented. The work covers the development of the alloy design and microstructure control as well as the processing technology applied for producing good quality alloy ingots and fabricating various components. The progress obtained in application research of the alloys is addressed. The important role that the combination of TMP and the post-TMP treatment affects on the microstructure and thus on the properties of the alloys is emphasized.
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Authors: Xiao Bo Liang, Shi Qiong Li, Jian Wei Zhang, Yun Jun Cheng
Abstract: The hot deformation characteristics of an as-cast Ti-22Al-25Nb alloy has been studied in the temperature range of 1323-1523K and the strain rate range of 0.001-10s-1, using hot compression tests. The experimental results indicated that discontinuous yielding occurs during the hot deformation performed at the strain rate of 10s-1, while the flow curves are of a steady-state type at lower strain rate range. Activation energy was obtained by analyzing the steady-state flow stress with a standard constitutive equation. They are 260-282kJ/mol in the temperature range of 1473-1523K, and 145-155kJ/mol in 1323-1423K. The processing map developed using the principles of dynamic material modeling exhibits three domains for the present alloy: 1) a domain of dynamic recrystallization of B2 phase in the temperature range of 1373-1423K at the strain rate range of 0.01-0.001s-1, with the power dissipation efficiency of about 35-50%, 2) a domain of dynamic recovery of B2 phase in the temperature range of 1473-1523K at the strain rate less than 0.01s-1, with the power dissipation efficiency of about 20-30%, 3) a domain of flow instability in the form of adiabatic shear band in the temperature range of 1323-1373K at the strain rate larger than 1s-1.
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Authors: Shi Qiong Li, Yong Mao, Jian Wei Zhang, Yun Jun Cheng
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