Al-Zn-Mg-Cu合金厚板沿厚度方向的显微组织和硬度

doi:10.13251/j.issn.0254-6051.2024.10.025

摘要/Abstract

摘要： 利用金相显微镜、场发射扫描电镜、透射电镜和硬度计研究了7050-T7451铝合金厚板沿厚度方向的显微组织、再结晶、第二相、时效析出相和无沉淀析出带,以及显微硬度的演变。结果表明:80 mm厚7050铝合金厚板在热处理过程中发生不同程度的再结晶,从表层到心部再结晶晶粒平均尺寸和面积分数沿厚度方向呈现出先降低后增加的趋势,并且各厚度层的再结晶面积分数均小于5%,而第二相平均尺寸逐渐增大,面积分数在表层较小而心部相对较大;晶内析出相密度在各厚度层基本无差异,但晶界析出相在心部比其他厚度层的更断续,尺寸更大,而表层则间距和尺寸更小。此外,在不同厚度层均存在明显的无沉淀析出带,并且其宽度随晶界析出相大小而变化,心部无沉淀析出带宽度较宽,约为94 nm。各厚度层的显微硬度值从表层到心部呈现出先增大后减小趋势,并与再结晶程度和亚稳态η′相有关。

关键词: 7050-T7451铝合金厚板, 显微组织, 再结晶, 无沉淀析出带, 显微硬度

Abstract: Evolution of the metallographic structure, recrystallization, second phase, aging precipitated phase, precipitation free zone and microhardness of the 7050-T7451 aluminum alloy thick plate with different thickness layers along the thickness direction were studied by means of metallographic microscopy, field emission scanning electron microscopy, transmission electron microscopy and hardness meter. The results show that the 80 mm thick 7050 aluminum alloy plate has different degrees of recrystallization during heat treatment. The average grain size and area fraction of recrystallization from the surface to the center show a trend of first decreasing and then increasing along the thickness direction, and the recrystallization area fraction of each thickness layer is less than 5%, while the average size of second phase increases gradually, the area fraction is smaller in the surface layer and relatively larger in the center. The density of intragranular precipitates is basically consistent in each thickness layer, but the precipitates at grain boundaries are more discontinuous and larger in size in the center compared to other thickness layers, while the spacing and size of the surface layer are smaller. In addition, there are obvious precipitate free zones(PFZ) in different thickness layers, and their widths vary with the size of precipitates at grain boundaries. The width of the precipitate free zone in the center is relatively wide, about 94 nm. The hardness values of each thickness layer show a trend of first increasing and then decreasing from the surface to the center, and are related to the degree of recrystallization and metastable η′ phase.

Key words: 7050-T7451 alloy thick plate, microstructure, recrystallization, precipitate free zone, microhardness

中图分类号:

TG146.2⁺1

王永红, 郭丰佳, 黄同瑊, 王经涛, 孙有政, 于继海. Al-Zn-Mg-Cu合金厚板沿厚度方向的显微组织和硬度[J]. 金属热处理, 2024, 49(10): 148-155.

Wang Yonghong, Guo Fengjia, Huang Tongjian, Wang Jingtao, Sun Youzheng, Yu Jihai. Microstructure and hardness of Al-Zn-Mg-Cu alloy thick plate along thickness direction[J]. Heat Treatment of Metals, 2024, 49(10): 148-155.

参考文献

[1]Azarniya A, Taheri A K, Taheri K K. Recent advances in ageing of 7××× series aluminum alloys: A physical metallurgy perspective[J]. Journal of Alloys and Compounds, 2019, 781: 945-983.
[2]Wang L, Bhatta L, Xiong H Q, et al. Mechanical properties and microstructure evolution of an Al-Cu-Li alloy subjected to rolling aging[J]. Journal of Central South University, 2021, 28: 1-18.
[3]Xiong H Q, Su L H, Kong C, et al. Development of high performance of Al alloys via cryo-forming: A review[J]. Advanced Engineering Materials, 2021, 23(6): 1-19.
[4]Lin Y C, Jiang Y Q, Zhang X C, et al. Effect of creep-aging processing on corrosion resistance of an Al-Zn-Mg-Cu alloy[J]. Materials and Design, 2014, 61: 228-238.
[5]Zhang Y R, Guo K, Sun J. Investigation on the milling performance of amputating clamping supports for machining with industrial robot[J]. International Journal of Advanced Manufacturing Technology, 2019, 102: 3573-3586.
[6]张荣. 固溶处理对7050铝合金超厚板高向组织与性能的影响[D]. 长沙: 中南大学, 2012.
[7]尹德都, 刘艳, 张德清, 等. 7050铝合金厚板淬火过程的数值模拟研究[J]. 云南大学学报(自然科学版), 2022, 44(6): 1227-1232.
Yin Dedu, Liu Yan, Zhang Deqing, et al. Numerical simulation study on quenching process of 7050 aluminum alloy thick plate[J]. Journal of Yunnan University (Natural Sciences Edition), 2022, 44(6): 1227-1232.
[8]罗家元, 贾二锁. 淬火残余应力对铝合金厚板裂纹应力强度因子及扩展趋势的影响[J]. 金属热处理, 2020, 45(5): 210-214.
Luo Jiayuan, Jia Ersuo. Effect of quenching residual stress on stress intensity factors and propagation trend of crack of aluminum alloy thick plate[J]. Heat Treatment of Metals, 2020, 45(5): 210-214.
[9]昌江郁, 陈送义, 陈康华, 等. 7056铝合金厚板轧制变形不均匀性的实验研究与数值模拟[J]. 中南大学学报(自然科学版), 2018, 49(8): 1914-1921.
Chang Jiangyu, Chen Songyi, Chen Kanghua, et al. Numerical simulation and experimental investigation of rolling deformation inhomogeneity of 7056 aluminum alloy thick plate[J]. Journal of Central South University (Science and Technology), 2018, 49(8): 1914-1921.
[10]王海金, 郑子樵, 范雪松. 2297-T87铝合金厚板力学性能的各向异性与厚向不均匀性[J]. 稀有金属材料与工程, 2016, 45(5): 1196-1202.
Wang Haijin, Zheng Ziqiao, Fan Xuesong. Mechanical anisotropy and inhomogeneity through thickness of 2297-T87 aluminum alloy thick plate[J]. Rare Metal Materials and Engineering, 2016, 45(5): 1196-1202.
[11]李承波, 何克准, 宋丰轩, 等. 7085-T651铝合金特厚板组织性能的不均匀性[J]. 航空材料学报, 2016, 36(6): 15-22.
Li Chengbo, He Kezhun, Song Fengxuan, et al. In homogeneity of microstructure and properties of 7085-T651 aluminum alloy extra-thick plate[J]. Journal of Aeronautical Materials, 2016, 36(6): 15-22.
[12]丛福官. 7B50铝合金厚板组织、性能及各向异性研究[D]. 沈阳: 东北大学, 2018.
Cong Fuguan. Research on microstructure, properties and anisotropy of 7B50 aluminum alloy plate[D]. Shenyang: Northeastern University, 2018.
[13]陈艳霞, 张建国, 王泓, 等. 2124铝合金各向异性的EBSD研究[J]. 金属热处理, 2011, 36(5): 79-82.
Chen Yanxia, Zhang Jianguo, Wang Hong, et al. EBSD investigation on the anisotropy of 2124 aluminum alloy[J]. Heat Treatment of Metals, 2011, 36(5): 79-82.
[14]冯帅, 孙黎明, 陈志国, 等. 7056铝合金厚板的组织和性能[J]. 稀有金属材料与工程, 2018, 47(10): 3088-3095.
Feng Shuai, Sun Liming, Chen Zhiguo, et al. Microstructure and mechanical properties of 7056 aluminum alloy thick plates[J]. Rare Metal Materials and Engineering, 2018, 47(10): 3088-3095.
[15]王东, 马宗义. 轧制工艺对7050铝合金显微组织和力学性能的影响[J]. 金属学报, 2008, 44(1): 49-54.
Wang Dong, Ma Zongyi. Effect of rolling process on microstructure and mechanical property of 7050 aluminum alloy [J]. Acta Metallurgica Sinica, 2008, 44(1): 49-54.
[16]Liu X Y, Pan O L, Fan X, et al. Microstructural evolution of Al-Cu-Mg-Ag alloy during homogenization[J]. Journal of Alloys and Compounds, 2009, 484(1-2): 790-794.
[17]Robson J D. Microstructural evolution in aluminium alloy 7050 during processing[J]. Materials Science and Engineering A, 2004, 382(1/2): 112-121.
[18]Li X M, Starink M J. The effect of compositional variations on the characteristics of coarse intermetallic particles in overaged 7000 Al alloys[J]. Materials Science and Technology, 2001, 17(11): 1324-1328.
[19]Deshpande N U, Gokhale A M, Denzer D K, et al. Relationship between fracture toughness, fracture path, and microstructure of 7050 aluminum alloy: Part I. Quantitative characterization[J]. Metallurgical and Materials Transactions A, 1998, 29(4): 1191-1201.
[20]Carvalho A L M, Renaudin L B, Zara A J, et al. Microstructure analysis of 7050 aluminum alloy processed by multistage aging treatments[J]. Journal of Alloys and Compounds, 2022, 907: 164400.
[21]王聪. 大飞机2024铝合金厚板热处理工艺及热轧模拟研究[D]. 长沙: 中南大学, 2012.
[22]Wang J W, Zhang S G, Lu Z F, et al. Microstructure evolution and properties comparation of industrial grade-maintained 7050-T7451 plate recycled from machining chips[J]. Journal of Materials Research and Technology, 2023, 25: 6011-6026.
[23]Ferragut R, Somoza A, Tolley A. Microstrucural evolution of 7012 alloy during the early stages of artificial aging[J]. Acta Materialia, 1999, 47(17): 4355-4364.
[24]陈小明, 宋仁国, 李杰. 7×××系铝合金的研究现状及发展趋势[J]. 材料导报, 2009, 23(2): 67-70.
Chen Xiaoming, Song Renguo, Li Jie. Current research status and development trends of 7××× series aluminum alloys[J]. Materials Reports, 2009, 23(2): 67-70.
[25]Wang Y L, Pan Q L, Wei L L, et al. Effect of retrogression and reaging treatment on the microstructure and fatigue crack growth behavior of 7050 aluminum alloy thick plate[J]. Materials and Design, 2014, 55: 857-863.
[26]魏雨虹. 热处理对7055铝合金组织及其性能的影响[D]. 哈尔滨: 哈尔滨理工大学, 2020.
Wei Yuhong. Effect of Heat Treatment on microstructure and properties of 7055 aluminum alloy [D]. Harbin: Harbin University of Science and Technology, 2020.
[27]谢志强. 大规格喷射成形7055铝合金组织演化及其对力学性能和淬透性影响研究[D]. 重庆: 重庆大学, 2020.
Xie Zhiqiang. Study on microstructure evolution and its effect on mechanical properties and hardenability of large-size spray formed 7055 alloy [D]. Chongqing: Chongqing University, 2020.
[28]冯迪, 张新明, 刘胜胆. 非等温回归再时效对7055铝合金中厚板的厚向组织及性能均匀性的影响[J]. 中国有色金属学报, 2015, 25(11): 3000-3010.
Feng Di, Zhang Xinming, Liu Shengdan. Effect of non-isothermal retrogression and re-ageing on through-thickness homogeneity of microstructure and properties in 7055 aluminum alloy medium thick plate [J]. The Chinese Journal of Nonferrous Metals, 2015, 25(11): 3000-3010.
[29]丛福官, 赵刚, 田妮, 等. 7150-T7751铝合金厚板性能的不均匀性[J]. 材料研究学报, 2013, 27(2): 144-148.
Cong Fuguan, Zhao Gang, Tian Ni, et al. Inhomogeneity of properties of 7150-T7751 aluminum alloy thick plate [J]. Chinese Journal of Materials Research, 2013, 27(2): 144-148.
[30]Shastry C R, Judd G. A study of grain boundary precipitate-free zone formation in an Al-Zn-Mg alloy[J]. Metallurgical and Materials Transactions B, 1971, 2(12): 3283-3287.
[31]陈旭. Al-Zn-Mg-Cu合金热处理工艺及组织性能研究[D]. 长沙: 中南大学, 2012.
Chen Xu. Study on the heat treatment, microstructure and properties of an Al-Zn-Mg-Cu alloy [D]. Changsha: Central South University, 2012.
[32]冯迪, 张新明, 刘胜胆, 等. 7A55铝合金厚板的微观组织和性能不均匀性[J]. 中南大学学报: 自然科学版, 2015, 46(8): 2824-2830.
Feng Di, Zhang Xinming, Liu Shengdan, et al. Inhomogeneity of microstructure and properties of 7A55 aluminum alloy thick plate[J]. Journal of Central South University: Science and Technology, 2015, 46(8): 2824-2830.
[33]Liu Y, Jiang D M, Li B Q, et al. Effect of cooling aging on microstructure and mechanical properties of an Al-Zn-Mg-Cu alloy[J]. Materials and Design, 2014, 57: 79-86.
[34]Sun Z C, Yin J L, Yang H. Microstructure evolution and microhardness of 7075 aluminum alloy during heat treatment by considering hot deformation history[J]. Advanced Materials Research, 2013, 699: 851-858.