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1 Vol.20 No.6 The Chinese Journal of Nonferrous Metals June (2010) ( ) OM SEM X DSC h (475 2 h) + ( h) 650 MPa 600 MPa 13.5% 7150 TG113 TG146.2 A Effect of solution treatment on microstructures and mechanical properties of 7150 aluminum alloy HAN Xiao-lei, XIONG Bai-qing, ZHANG Yong-an, LI Zhi-hui, ZHU Bao-hong, WANG Feng, LIU Hong-wei (State Key Laboratory of Nonferrous Metals and Processes, General Research Institute for Nonferrous Metals, Beijing , China) Abstract: The effects of solution treatment on the microstructures and mechanical properties of 7150 aluminum alloy extrusion plate were studied by OM, SEM, XRD, DSC and room temperature tensile test. The results show that the coarse second phase dissolves more adequately when the alloy is solution treated at higher temperature for longer time. The overheated structure appears in alloys when quenched at 480, and the temperature at which overheated structure appears cannot be enhanced by two-stage solution. The trend of microstructure coarsening and recrystallization appears with prolongating the solution time. The suited solution of the alloy is single-stage solution of 475, 2 h. After solution and peak aging of (475, 2 h)+(120, 24 h), the ultimate tensile strength, yield strength and elongation are 650 MPa, 600 MPa and 13.5%, respectively. Key words: 7150 Al alloy; solution treatment; microstructure; mechanical properties Al-Zn-Mg-Cu [1] Zn Mg Cu Fe Si [2] 1991 Alcoa T T6 [3 5] 7150-T77(25 mm ) 614 MPa 7150-T77 [6] [7] ( ) (2007BAE38B06) zhangyongan@grinm.com

2 [8] [9 10] ~30 µm [11 12] XRD MgZn 2 1 Al-6.33Zn-2.35Mg-2.39Cu-0.12Zr Al Zn Mg Al-Cu Al-Zr ( h)+( h) 100 mm 25 mm h h 1 h SX (Axiocert200MAT) (HITACHI S4800) Keller X CuK α (2θ) 10 ~90 DSC NETZSCH STA 409C/CD 10 K/min MTS 810, 1 mm/min L (a) 1(b) Fig.1 Three-dimensional metallograph of as-extruded 7150 alloy: (a) Lower-magnification; (b) High-magnification a Al 2 CuMg b Al 2 CuMg 1 Cu Al 2 Cu Al 2 CuMg Cu Mg Cu Al 2 CuMg Cu c Fe Al 7 Cu 2 Fe Fe Fe SEM Fe [13] d Zn 3 XRD 3 Al MgZn 2 Al 2 CuMg 4 DSC 4

3 Fig.2 Microstructure of as-extruded 7150 alloy 1 2 Table 1 EDS analyses results of phases in Fig.2 Phase Mole fraction/% Al Zn Mg Cu Fe Mn a b c d X Fig.3 XRD patterns of as-extruded 7150 alloy MPa 305 MPa 10.5% h h DSC Fig.4 DSC curves of as-extruded 7150 alloy 1 µm MgZn 2 Al 2 CuMg h MgZn 2 Al 2 CuMg h DSC DSC [14] Al 2 CuMg MgZn 2 [15] [16 17] h 2 7 e f 2 e Al 2 CuMg f Cu Mg Cu Al 2 CuMg Cu 8 1 h h 8

4 h Fig.5 Metallographs of 7150 alloy after solution treatment for 1 h at different temperatures: (a) 470, transverse section; (b) 470, longitudinal section; (c) 475, transverse section; (d) 475, longitudinal section; (e) 480, transverse section; (f) 480, longitudinal section Fig.6 Metallographs of transverse section of 7150 alloy after solution treatments at 475 for different times: (a) 1 h; (b) 2 h; (c) 4 h

$7 Phase Mole fraction/% Al Zn Mg Cu e 54.85 1.69 23.22 20.24 f 40.27 2.30 8.25 49.19 9 7150 Fig.$ p0.2 A 650 MPa 600 MPa 13.5% 8 7150 Fig.

5 h Fig.7 Microstructure of coarse second phase of alloy after 475, 2 h solution treatment 2 7 Table 2 Chemical composition of phases in Fig.7 Phase Mole fraction/% Al Zn Mg Cu e f Fig.9 Effect of solution time on tensile properties of 7150 alloy aged 120 for 24 h after solution at h (475 2 h)+( h) R m R p0.2 A 650 MPa 600 MPa 13.5% Fig.8 Effect of solution temperature on tensile properties of 7150 alloy (aging at 120, 24 h after solution for 1 h) 475 (475 1 h)+( h) R m R p0.2 A 645 MPa 600 MPa 13.0% h h R m R p MPa 595 MPa R m R p0.2 A 645 MPa 595 MPa 17% (450 1 h)+ 1 h+(475 1 h) + ( h) (460 1 h)+ 1 h+(475 1 h)+ ( h) 3

6 Fig.12 Effect of second stage solution temperature on tensile properties of alloy at first stage solution temperature of Table 3 Comparison of tensile properties of alloy after single-stage solution and two-stage solution Solution treatment R m /MPa R p0.2 /MPa A/% (475, 2 h)+(120, 24 h) Fig.10 Metallographs of alloys with different two-stage solution treatments: (a) (450, 1 h)+(heating up for 1 h)+ (475, 1 h); (b) (450, 1 h)+(heating up for 1 h)+(480, 1 h); (c) (450, 1 h)+(heating up for 1 h)+(485, 1 h) (450, 1 h)+(heating up for h)+(475, 1 h)+(120, 24 h) (460, 1 h)+(heating up for h)+(475, 1 h)+(120, 24 h) h Fig.11 Effect of second stage solution temperature on tensile properties of alloy at first stage solution temperature of 450 1) Al 2 CuMg Cu h MgZn 2 Al 2 CuMg Cu 2)

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untitled 20 1 2010 10 Vol.20 Special 1 The Chinese Journal of Nonferrous Metals Oct. 2010 1004-0609(2010)S1-s0127-05 Ti-6Al-4V 1 2 2 (1. 710016 2., 710049) 500~1 000 20 Ti-6Al-4V(TC4) TC4 800 TC4 800 TC4 TC4 800