时效热处理对建筑铝合金型材组织与性能的影响
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摘要
采用显微硬度计、拉伸试验机、电导率测试仪、透射电镜、晶间腐蚀和电化学腐蚀等手段,研究了单级时效、双级时效和回归再时效对Al-6. 6Zn-2. 2Mg-2. 0Cu-0. 1Zr合金组织、力学性能和耐腐蚀性能的影响。结果表明,T6态合金的硬度、抗拉强度和规定塑性延伸强度高于双级时效态合金;随着回归时间的延长,合金的硬度先增加而后减小、电导率逐渐增加,抗拉强度和规定塑性延伸强度都呈现单调递减趋势,RRA工艺下试验合金的强度要低于T6态,但是明显高于双级时效态。T6态合金的晶间腐蚀最严重,RRA 175℃×3 h和RRA 195℃×1 h合金的晶间腐蚀较轻且与双级时效态相当,除T6态合金的腐蚀等级为4级外,RRA态和双级时效态合金的腐蚀等级都为3级。RRA 175℃×3 h、RRA 195℃×1 h合金和双级时效态合金的极化曲线相似、腐蚀电位较为接近,且腐蚀电位都较T6态合金发生正向移动,而腐蚀电流密度都明显低于T6态合金; RRA 175℃×3 h、RRA 195℃×1 h合金和双级时效态合金的耐腐蚀性能相当,且都明显高于T6态合金。
The effects of single-stage aging,double-stage aging and regression re-aging on the microstructure,mechanical properties and corrosion resistance of Al-6. 6 Zn-2. 2 Mg-2. 0 Cu-0. 1 Zr alloy were studied by means of microhardness tester,tensile testing machine,conductivity tester,transmission electron microscope,and intergranular corrosion as well as electrochemical corrosion tests. The results show that the hardness,tensile strength and yield strength of the alloy in double-stage aging state are higher than that in the T6 state. With the prolongation of regression time,the hardness of the alloy increases first and then decreases,the electrical conductivity increases gradually,and the tensile strength and yield strength of the alloy show a monotonic decreasing trend. The strength of the alloy in RRA states is lower than that in the T6 state,but significantly higher than that in the double-stage aging state. The intergranular corrosion in the T6 state is the most serious,that in both the RRA 175 ℃ × 3 h and the RRA 195 ℃ × 1 h states is lighter and comparable to that in the two-stage aging state.Except that in T6 state is grade 4,the corrosion grade of the alloy in all the other states is grade 3. For the RRA 175 ℃ × 3 h and RRA 195 ℃ ×1 h and two-stage ageing states,the polarization curves and corrosion potentials are similar,while the corrosion potentials are close to that in the T6 state,and the corrosion current density is lower than that in the T6 state. The corrosion resistance of the alloy in the RRA 175 ℃ ×3 h and RRA 195 ℃ × 1 h states as well as the two-stage aging states are similar,and all are significantly higher than in the T6 state.
The effects of single-stage aging,double-stage aging and regression re-aging on the microstructure,mechanical properties and corrosion resistance of Al-6. 6 Zn-2. 2 Mg-2. 0 Cu-0. 1 Zr alloy were studied by means of microhardness tester,tensile testing machine,conductivity tester,transmission electron microscope,and intergranular corrosion as well as electrochemical corrosion tests. The results show that the hardness,tensile strength and yield strength of the alloy in double-stage aging state are higher than that in the T6 state. With the prolongation of regression time,the hardness of the alloy increases first and then decreases,the electrical conductivity increases gradually,and the tensile strength and yield strength of the alloy show a monotonic decreasing trend. The strength of the alloy in RRA states is lower than that in the T6 state,but significantly higher than that in the double-stage aging state. The intergranular corrosion in the T6 state is the most serious,that in both the RRA 175 ℃ × 3 h and the RRA 195 ℃ × 1 h states is lighter and comparable to that in the two-stage aging state.Except that in T6 state is grade 4,the corrosion grade of the alloy in all the other states is grade 3. For the RRA 175 ℃ × 3 h and RRA 195 ℃ ×1 h and two-stage ageing states,the polarization curves and corrosion potentials are similar,while the corrosion potentials are close to that in the T6 state,and the corrosion current density is lower than that in the T6 state. The corrosion resistance of the alloy in the RRA 175 ℃ ×3 h and RRA 195 ℃ × 1 h states as well as the two-stage aging states are similar,and all are significantly higher than in the T6 state.
引文
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[12]黄彦天,严伟林.多向锻造及时效对高强铝合金力学和晶间腐蚀性能的影响[J].热加工工艺,2017,46(6):198-201.Huang Yantian,Yan Weilin. Effect of multi-direction forging and aging on mechanical and intergranular corrosion properties of high strength aluminium alloys[J]. Hot Working Technology,2017,46(6):198-201.
[13]刘平礼,王明坤,孙文超,等.显微组织结构对Al-Zn-Mg合金应力腐蚀抗性的影响[J].铝加工,2017(4):16-21.Liu Pingli, Wang Mingkun, Sun Wenchao, et al. Effect of microstructure on stress corrosion resistance of Al-Zn-Mg alloys[J].Aluminum fabrication,2017(4):16-21.
[14]许晓静,朱金鑫,郭云飞,等.固溶-冷变形-时效工艺下超高强Al-Zn-Mg-Cu系铝合金的组织及性能[J].稀有金属材料与工程,2017,46(10):2981-2986.Xu Xiaojing,Zhu Jinxin,Guo Yunfei,et al. Microstructure and properties of ultra-high strength Al-Zn-Mg-Cu alloy under solution-cold deformation-aging process[J]. Rare Metal Materials and Engineering,2017,46(10):2981-2986.
[2]杨丽辉,刘志勇,王明星,等. Sc及回归再时效处理对7075铝合金抗应力腐蚀性能的影响[J].金属热处理,2018,43(2):35-39.Yang Lihui,Liu Zhiyong,Wang Xingxing,et al. Effects of Sc and regression aging treatment on stress corrosion resistance of 7075aluminum alloy[J]. Heat Treatment of Metals,2018,43(2):35-39.
[3]Ozer G,Karaaslan A. Properties of AA7075 aluminum alloy in aging and retrogression and reaging process[J]. Transactions of Nonferrous Metals Society of China,2017,27(11):2357-2362.
[4]Oliveira A F,Barros M C D,Cardoso K R,et al. The effect of RRA on the strength and SCC resistance on AA7050 and AA7150 aluminium alloys[J].Materials Science and Engineering A(Structural Materials:Properties,Microstructure and Processing),2004,379(1/2):321-326.
[5]刘静安,谢水生.铝合金材料应用与开发[M].北京:冶金工业出版社,2011.Liu Jingan,Xie Shuisheng. Application and Development of Aluminum Alloy Materials[M]. Beijing:Metallurgical Industry Press,2011.
[6]李秋梅,孙建波,任晓雪,等.高温RRA对7075铝合金微观组织与性能的影响[J].热加工工艺,2018,47(8):129-132.Li Qiumei,Sun Jianbo,Ren Xiaoxue,et al. Effect of RRA on the microstructure and properties of 7075 aluminum alloy[J]. Hot Working Technology,2018,47(8):129-132.
[7]Lin J C,Liaoh L,Jehng W D,et al. Effect of heat treatments on the tensile strength and SCC-resistance of AA7050 in an alkaline saline solution[J]. Corrosion Science,2006,48(10):0-3156.
[8]滕天娇,谭子昊,杨林,等.回归再时效处理对Al-6Zn-2Mg-2Cu合金力学性能及耐蚀性的影响[J].材料热处理学报,2018,39(1):14-19.Teng Tianjiao,Tan Zihao,Yang Lin,et al. Effect of regression aging treatment on mechanical properties and corrosion resistance of Al-6Zn-2Mg-2Cu alloy[J]. Transactions of Materials and Heat Treatment,2018,39(1):14-19.
[9]Su R,Su J,Qu Y,et al. Retrogression on corrosion behavior of spray formed Al-7075[J]. Journal of Materials Research,2017,32(13):2621-2627.
[10]齐跃,郗建豪,林忠亮,等.不同时效制度对7075铝合金组织及抗应力腐蚀性能的影响[J].材料热处理学报,2018,39(11):38-45.Qi Yue,Li Jianhao,Lin Zhongliang,et al. Effects of different aging regimes on the structure and stress corrosion resistance of 7075aluminium alloy[J]. Transactions of Materials and Heat Treatment,2018,39(11):38-45.
[11]Su R M,Qu Y D,Li R D. Effect of aging treatments on the mechanical and corrosive behaviors of spray-formed 7075 alloy[J]. Journal of Materials Engineering and Performance,2014,23(11):3842-3848.
[12]黄彦天,严伟林.多向锻造及时效对高强铝合金力学和晶间腐蚀性能的影响[J].热加工工艺,2017,46(6):198-201.Huang Yantian,Yan Weilin. Effect of multi-direction forging and aging on mechanical and intergranular corrosion properties of high strength aluminium alloys[J]. Hot Working Technology,2017,46(6):198-201.
[13]刘平礼,王明坤,孙文超,等.显微组织结构对Al-Zn-Mg合金应力腐蚀抗性的影响[J].铝加工,2017(4):16-21.Liu Pingli, Wang Mingkun, Sun Wenchao, et al. Effect of microstructure on stress corrosion resistance of Al-Zn-Mg alloys[J].Aluminum fabrication,2017(4):16-21.
[14]许晓静,朱金鑫,郭云飞,等.固溶-冷变形-时效工艺下超高强Al-Zn-Mg-Cu系铝合金的组织及性能[J].稀有金属材料与工程,2017,46(10):2981-2986.Xu Xiaojing,Zhu Jinxin,Guo Yunfei,et al. Microstructure and properties of ultra-high strength Al-Zn-Mg-Cu alloy under solution-cold deformation-aging process[J]. Rare Metal Materials and Engineering,2017,46(10):2981-2986.