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Zhou H.,Harbin Institute of Technology | Kong F.,Harbin Institute of Technology | Wu K.,Beijing Hangxing Machinery Manufacture Ltd Corporation | Wang X.,Harbin Institute of Technology | Chen Y.,Harbin Institute of Technology
Materials and Design | Year: 2017

The relationship of the microstructure and tensile properties between the rolling conditions was investigated by fabricating Ti-44Al-8Nb-(W, B, Y) alloy sheets under different rolling conditions. The original nearly lamellar structure with mean colony sizes of 120 μm was significantly refined to a duplex microstructure with mean grain sizes of 5–6.1 μm. The mechanism of lamellar colonies evolution is discontinuous dynamic recrystallization (DDRX), which occurs at tri-boundaries, phase boundaries, and twin boundaries. The microstructure refinement and uniformity of as-rolled alloys was improved by increasing total reduction. As the total rolling reduction increases from 43% to 72%, the volume fraction of remnant lamellar colonies decreases from 28.5% to 6.8% and newly formed α2/γ lamellar colonies increases from 13.7% to 33.7%. The mean grain sizes of recrystallized grains also can be refined from 5.4 μm to 3.6 μm. The tensile properties exhibit an increasing trend with the increase of total rolling reduction. When the total rolling reduction is 72%, the alloy exhibits a small fluctuation of mechanical properties. The UTS is higher than 1106 MPa with an elongation value of 0.94% at room temperature. At 800 °C, the UTS remains as high as 744 MPa with an elongation value of over 40%. © 2017 Elsevier Ltd


Wu K.,Beijing Hangxing Machinery Manufacture Ltd Corporation | Yao W.,Beijing Hangxing Machinery Manufacture Ltd Corporation | Fan X.-L.,Beijing Hangxing Machinery Manufacture Ltd Corporation | You F.-H.,Beijing Hangxing Machinery Manufacture Ltd Corporation | Wang Z.-M.,Beijing Hangxing Machinery Manufacture Ltd Corporation
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

The effect of heat treatment processes on microstructure and mechanical properties of laser-welded BTi-6431S alloy was investigated by means of optical microscope, tensile tester and microhardness tester. The results show that the as-welded microstructure of laser-welded BTi-6431S alloy is composed of massive primary α phase and lamellar β phase transformation microstructure. The various α phases can be obtained by different heat treatment processes. With the increase of heat treatment temperature, the secondary α-phase increases, meanwhile the tensile and yield strength of the welded joints at room and high temperature increases, while the elongation increases firstly and then decreases. The best microhardness appears when the temperature is 650℃. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.


Wu K.,Beijing Hangxing Machinery Manufacture Ltd Corporation | Yao W.,Beijing Hangxing Machinery Manufacture Ltd Corporation | Fan X.,Beijing Hangxing Machinery Manufacture Ltd Corporation | You F.,Beijing Hangxing Machinery Manufacture Ltd Corporation | Wang Z.,Beijing Hangxing Machinery Manufacture Ltd Corporation
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

Effect of heat treatment on microstructure and mechanical properties of argon arc-welded BTi-6431S alloy was investigated by means of optical microscope, tensile tester and micro-hardness tester. The results show that as-welded microstructure of argon arc-welded BTi-6431S alloy is composed of primary α-phase block and lamellar β-phase. The various α-phase and β-phase can be obtained by different heat treatment processes. With the increase of heat treatment temperature, the primary α-phase decreases, meanwhile the fine needle-like α' martensite and the globular α phase increase and are coarse. The tensile strength, yield strength and the elongation at room and high temperature increase firstly and then decrease. The high micro-hardness appears when heat treating at 650 ℃. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.

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