挤压变形6061铝合金的疲劳变形及断裂研究
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摘要
综合性能优良的铝合金已广泛应用于不同的工业领域,对其力学性能尤其是疲劳性能的要求则越来越高。一般说来,疲劳失效是工程结构件的主要破坏形式之一,铝合金亦不例外,因此,研究铝合金的疲劳行为不仅具有理论价值,而且也具有一定的工程实用价值。
铝合金的疲劳行为主要受其化学成分、显微组织等因素的影响。尽管人们已经对铝合金的疲劳行为进行了一定程度的研究,但关于不同热处理状态6061铝合金的低周疲劳问题的研究尚没有见到,因此,研究挤压态及热处理态6061铝合金低周疲劳行为,总结其疲劳变形的一般规律,确定相应的疲劳裂纹萌生和扩展模式,以期为提高6061铝合金的疲劳性能提供可靠的理论基础,同时对6061铝合金在工程实际中的可靠使用以及相关结构件的抗疲劳设计提供必要的理论依据具有重要意义。
实验结果表明,不同热处理的挤压态6061铝合金在疲劳变形期间可以表现为循环应变硬化、循环稳定现象;时效处理后提高了挤压态6061铝合金循环变形抗力,而固溶处理则显著降低合金循环变形抗力;在较高的外加总应变幅下,固溶态6061铝合金的疲劳寿命最长,而时效态6061铝合金的疲劳寿命最短;当外加总应变幅较低时,挤压态6061铝合金的疲劳寿命高于经过热处理的合金的疲劳寿命;对于不同热处理的挤压态6061铝合金而言,其弹性应变幅、塑性应变幅与疲劳断裂时的载荷反向周次之间呈直线关系。
疲劳断口形貌分析结果表明,在外加总应变控制的疲劳加载条件下,不同加工处理状态的挤压变形6061铝合金的疲劳裂纹均是以穿晶方式萌生于疲劳试样表面,并以穿晶方式扩展。
Aluminum alloy has been widely applied to different industrial sectors for its excellent comprehensive properties, while its mechanical properties, especially fatigue performance are required increasingly high. Generally speaking, the fatigue failure is one of the major failure formats of engineering structural components, and the aluminum alloy is not an exception, and therefore the study of fatigue behavior of aluminum alloy not only has theoretical value, but also has some practical value in engineering.
The fatigue behavior of aluminum alloy ware mainly influenced by their chemical composition, microstructure and other factors. Although the fatigue behavior of aluminum alloy has been researched in a certain degree, the research of different heat treatment states 6061 aluminum alloy on low-cycle fatigue is still not seen. Therefore, researching the low-cycle fatigue behavior of extruded and heat treatment state 6061aluminum alloy, summing up the general laws of the fatigue deformation, determining the corresponding fatigue crack initiation and expansion patterns, would provide a reliable theoretical basis for 6061 aluminum alloy to enhance the fatigue properties. At the same time, it is of great significance to provide the necessary theoretical basis for the use of 6061 aluminum alloy in engineering practice and the anti-fatigue design of relevant structural parts.
The experimental results show that different heat treatment of extruded 6061 aluminum alloy can be expressed as the cyclic strain hardening, cyclic stabilization during the fatigue deformation; the aging treatment can increase the cyclic deformation resistance of the extruded 6061 alloy, but the solution treatment can significantly decrease the cyclic deformation resistance of the extruded 6061 alloy; under the higher applied total strain amplitude, the fatigue life of soiled solution state 6061 aluminum alloy was the longest while the fatigue life of the aging state 6061 aluminum alloy was the shortest; when applied total strain amplitude was low, the fatigue life of extruded 6061 aluminum alloy was higher than heat-treated alloy’s; to different heat treatment of extruded 6061 aluminum alloy, the relation between plastic and elastic strain amplitudes as well as reversals to failure can be described by Coffin-Manson and Basquin equations respectively.
Fatigue fracture morphology analysis showed that the fatigue crack of different deformated 6061 aluminum alloy which were under the applied total strain-controlled fatigue loading conditions were transgranular mode to initiate in the fatigue specimen surface, and to extended in the transgranular mode.
铝合金的疲劳行为主要受其化学成分、显微组织等因素的影响。尽管人们已经对铝合金的疲劳行为进行了一定程度的研究,但关于不同热处理状态6061铝合金的低周疲劳问题的研究尚没有见到,因此,研究挤压态及热处理态6061铝合金低周疲劳行为,总结其疲劳变形的一般规律,确定相应的疲劳裂纹萌生和扩展模式,以期为提高6061铝合金的疲劳性能提供可靠的理论基础,同时对6061铝合金在工程实际中的可靠使用以及相关结构件的抗疲劳设计提供必要的理论依据具有重要意义。
实验结果表明,不同热处理的挤压态6061铝合金在疲劳变形期间可以表现为循环应变硬化、循环稳定现象;时效处理后提高了挤压态6061铝合金循环变形抗力,而固溶处理则显著降低合金循环变形抗力;在较高的外加总应变幅下,固溶态6061铝合金的疲劳寿命最长,而时效态6061铝合金的疲劳寿命最短;当外加总应变幅较低时,挤压态6061铝合金的疲劳寿命高于经过热处理的合金的疲劳寿命;对于不同热处理的挤压态6061铝合金而言,其弹性应变幅、塑性应变幅与疲劳断裂时的载荷反向周次之间呈直线关系。
疲劳断口形貌分析结果表明,在外加总应变控制的疲劳加载条件下,不同加工处理状态的挤压变形6061铝合金的疲劳裂纹均是以穿晶方式萌生于疲劳试样表面,并以穿晶方式扩展。
Aluminum alloy has been widely applied to different industrial sectors for its excellent comprehensive properties, while its mechanical properties, especially fatigue performance are required increasingly high. Generally speaking, the fatigue failure is one of the major failure formats of engineering structural components, and the aluminum alloy is not an exception, and therefore the study of fatigue behavior of aluminum alloy not only has theoretical value, but also has some practical value in engineering.
The fatigue behavior of aluminum alloy ware mainly influenced by their chemical composition, microstructure and other factors. Although the fatigue behavior of aluminum alloy has been researched in a certain degree, the research of different heat treatment states 6061 aluminum alloy on low-cycle fatigue is still not seen. Therefore, researching the low-cycle fatigue behavior of extruded and heat treatment state 6061aluminum alloy, summing up the general laws of the fatigue deformation, determining the corresponding fatigue crack initiation and expansion patterns, would provide a reliable theoretical basis for 6061 aluminum alloy to enhance the fatigue properties. At the same time, it is of great significance to provide the necessary theoretical basis for the use of 6061 aluminum alloy in engineering practice and the anti-fatigue design of relevant structural parts.
The experimental results show that different heat treatment of extruded 6061 aluminum alloy can be expressed as the cyclic strain hardening, cyclic stabilization during the fatigue deformation; the aging treatment can increase the cyclic deformation resistance of the extruded 6061 alloy, but the solution treatment can significantly decrease the cyclic deformation resistance of the extruded 6061 alloy; under the higher applied total strain amplitude, the fatigue life of soiled solution state 6061 aluminum alloy was the longest while the fatigue life of the aging state 6061 aluminum alloy was the shortest; when applied total strain amplitude was low, the fatigue life of extruded 6061 aluminum alloy was higher than heat-treated alloy’s; to different heat treatment of extruded 6061 aluminum alloy, the relation between plastic and elastic strain amplitudes as well as reversals to failure can be described by Coffin-Manson and Basquin equations respectively.
Fatigue fracture morphology analysis showed that the fatigue crack of different deformated 6061 aluminum alloy which were under the applied total strain-controlled fatigue loading conditions were transgranular mode to initiate in the fatigue specimen surface, and to extended in the transgranular mode.
引文
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[2]周惦武,刘金水,肖锋,等.铝合金挤压型材工艺及在汽车中的应用.金属成形工艺, 2004, 22(1): 62-64.
[3]邱庆荣,孙宝德,周尧和.铝合金铸件在汽车上的应用.铸造, 1998 (1): 46-49.
[4]田荣章,王祝堂.铝合金及其加工手册.长沙:中南大学出版社, 2000.
[5]周晓霞,张仁元.稀土元素在铝合金中的作用和应用.新技术新工艺, 2003 (4): 43-45.
[6]孙丹丹,李文东.铝合金在汽车中的应用.山东内燃机, 2003 (1): 34-36.
[7]林肇琦.有色金属材料学.沈阳:东北工学院出版社, 1986.
[8]盛若川.提高6061-T6铝合金强度值的探讨.杭州:杭氧科技, 2002 (3-4):31-32.
[9]束德林.工程材料力学性能.北京:机械工业出版社, 2007.
[10] Duquette D J. General fatigue resistance and crack nucleation in metals and alloys. Metal Park: American Society for Metals, 1979.
[11] Kim S W, Han S W, Lee U J, et al. Effects of solidification structure on fatigue crack growth in rheocast and thixocast Al-Si-Mg alloys. Materials Letters, 2003, 58: 257-261.
[12]徐灏.疲劳强度.北京:高等教育出版社, 1988.
[13] Altenberger I, Scholtes B. Improvement of fatigue behaviour of mechanically surface treated materials by annealing. Scripta Materialia, 1999, 41(8): 873-881.
[14]龙国胜,郦正能,何庆芝,等.高强度铝合金小裂纹疲劳扩展特性.北京航空航天大学学报, 1996, 22(5): 603-606
[15]常红,王俭秋,韩恩厚.环境和缺口形状对LY12CZ铝合金疲劳短裂纹扩展的影响.机械强度, 2004, 26(S): 39-41.
[16] Blankenship C P, Kaisand L R. Elevated temperature fatigue crack propagation behavior of an Al-Li-Cu-Mg-Ag-Zr alloy. Scripta Materialia, 1996, 34(9): 1455-1460.
[17]陈玮.桥用铝合金的低周疲劳亚结构.兵器材料科学与工程, 1994, 17(5): 30-34.
[18] Guang Ran, Zhou J, Wang Q G. The effect of hot isostatic pressing on the microstructure and tensile properties of an unmodified A356-T6 cast aluminum alloy. Journal of Alloys and Compounds, 2006, 42(1~2): 80-86.
[19] Atxaga G, Pelayo A, Irisarri A M. Effect of microstructure on fatigue behaviour of cast Al-7Si-Mg alloy. Materials Science and Technology, 2001, 17(4): 446-450.
[20] Lados D A, Apelian D. Fatigue crack growth characteristics in cast Al-Si-Mg alloys Part I. Effect of processing conditions and microstructure. Materials Science and Engineering A, 2004, 385: 200.
[21] Seniw M E, Conley J G. The effect of microscopic inclusion locations and silicon segregation on fatigue lifetimes of aluminum alloy A356 castings. Materials Science and Engineering A, 2000, 285: 438.
[22] Wang Q G, Apelian D, Lados D A. Fatigue behavior of A356-T6 aluminum cast alloys. Part I - Effect of casting defects. Journal of Light Metals, 2001, 1(1): 73-84.
[23] Boileau J M, Allison J E. The effect of solidification time and heat treatment on the fatigue properties of a cast 319 aluminum alloy. Metallurgical and Materials Transactions A, 2003, 34 (9): 1807-1820.
[24] Bray G H, Glazov M, Rioja R J, et al. Effect of artificial aging on the fatigue crack propagation resistance of 2000 series aluminum alloys. International Journal of Fatigue, 2001, 23 (S): 265-276.
[25]杨平生,刘炎,张萌,等.纯铝和铝合金的低周冲击疲劳行为.南昌大学学报(理科版), 1996, 20(2): 156-160.
[26]王莉,蒋大鸣.时效对6063铝合金力学性能及阻尼特性的影响.轻合金加工技术, 2003, 31(12): 35-37.
[27]周敬恩,冉广. A356铸造铝合金的疲劳裂纹萌生及短裂纹扩展研究.金属热处理, 2008, 33(1): 34-42.
[28]朱正宇,何国求,陈成澍. ZL101铝合金低周疲劳行为研究.特种铸造及有色合金, 2007, 27(4): 256-260.
[29]刘延斌,刘志义,李云涛,等.时效对2524铝合金热稳定性的影响.材料研究学报, 2007, 21(6): 585-588.
[30]李海,郑子樵,魏修宇,等.时效析出对2E12铝合金疲劳断裂行为的影响.中国有色金属学报, 2008, 18(4): 589-594.
[31]莫德锋,何国求,朱正宇,等. Al-7Si-0.3Mg合金低周疲劳行为及其机理.特种铸造及有色合金, 2008, 28(7): 493-496.
[32]李晗. 2024铝合金薄板的热处理工艺与性能研究: (硕士学位论文).西安:西北工业大学, 2007.
[33]董显娟.时效制度对7B04铝合金组织与性能的影响: (硕士学位论文).长沙:中南大学, 2004.
[34]沈华龙,吴运新,熊卫民.振动时效应用于铝合金时动应力的选择.材料工程, 2009 (4): 18-22
[35] SHIPILOV S A.腐蚀疲劳裂纹扩展的机理.中国腐蚀与防护学报, 2004, 24(6): 321-333.
[36]何建平. NaCl电解液薄层下LC4CS铝合金腐蚀疲劳性能.南京航空航天大学学报, 2004, 36(4): 412-416.
[37]郑晓玲.民机结构耐久性与损伤容限设计手册(下册).北京:航空工业出版社, 2003.
[38]秦剑波,王生楠,刘亚龙,等.腐蚀环境下2024-T3铝合金疲劳裂纹扩展和剩余强度实验研究.材料工程, 2006 (3): 14-17.
[39] Congleton J, Charles E A. Review on effect of cyclic loadinon environmental assisted cracking of alloy 600 in typicanuclear coolant waters. Corrosion Science, 2001, 43: 2265-2279.
[40]刘祖铭,曾凡阳,鲁礼菊,等.环境对LY12CZ铝合金典型螺接件疲劳性能的影响.中国腐蚀与防护学报, 2004, 24(5): 267-271.
[41]鲍蕊,张建宇,费斌军.潮湿空气环境对2024-T3铝合金疲劳性能的影响.材料研究学报, 2007, 21(5): 547-550.
[42]杨胜,易丹青,杨守杰,等.腐蚀环境下2E12航空铝合金疲劳裂纹扩展行为研究.材料工程, 2007 (12): 26-34.
[43]钱建刚,李荻,郭宝兰,等. LC4高强铝合金的腐蚀性能研究.腐蚀与防护, 2002, 23(8): 340-343.
[44]向磊,刘培英,周铁涛.采用自制简易装置评定高强铝合金的应力腐蚀性能.物理测试, 2005, 23(5): 32-35.
[45] Raske D T, Morrow J. Mechanics of materials in low cycle fatigue testing. ASTM STP 465. Philadelphia: American Society for Testing and Materials, 1969.
[46]王磊.材料的力学性能.沈阳:东北大学出版社, 2005.
[2]周惦武,刘金水,肖锋,等.铝合金挤压型材工艺及在汽车中的应用.金属成形工艺, 2004, 22(1): 62-64.
[3]邱庆荣,孙宝德,周尧和.铝合金铸件在汽车上的应用.铸造, 1998 (1): 46-49.
[4]田荣章,王祝堂.铝合金及其加工手册.长沙:中南大学出版社, 2000.
[5]周晓霞,张仁元.稀土元素在铝合金中的作用和应用.新技术新工艺, 2003 (4): 43-45.
[6]孙丹丹,李文东.铝合金在汽车中的应用.山东内燃机, 2003 (1): 34-36.
[7]林肇琦.有色金属材料学.沈阳:东北工学院出版社, 1986.
[8]盛若川.提高6061-T6铝合金强度值的探讨.杭州:杭氧科技, 2002 (3-4):31-32.
[9]束德林.工程材料力学性能.北京:机械工业出版社, 2007.
[10] Duquette D J. General fatigue resistance and crack nucleation in metals and alloys. Metal Park: American Society for Metals, 1979.
[11] Kim S W, Han S W, Lee U J, et al. Effects of solidification structure on fatigue crack growth in rheocast and thixocast Al-Si-Mg alloys. Materials Letters, 2003, 58: 257-261.
[12]徐灏.疲劳强度.北京:高等教育出版社, 1988.
[13] Altenberger I, Scholtes B. Improvement of fatigue behaviour of mechanically surface treated materials by annealing. Scripta Materialia, 1999, 41(8): 873-881.
[14]龙国胜,郦正能,何庆芝,等.高强度铝合金小裂纹疲劳扩展特性.北京航空航天大学学报, 1996, 22(5): 603-606
[15]常红,王俭秋,韩恩厚.环境和缺口形状对LY12CZ铝合金疲劳短裂纹扩展的影响.机械强度, 2004, 26(S): 39-41.
[16] Blankenship C P, Kaisand L R. Elevated temperature fatigue crack propagation behavior of an Al-Li-Cu-Mg-Ag-Zr alloy. Scripta Materialia, 1996, 34(9): 1455-1460.
[17]陈玮.桥用铝合金的低周疲劳亚结构.兵器材料科学与工程, 1994, 17(5): 30-34.
[18] Guang Ran, Zhou J, Wang Q G. The effect of hot isostatic pressing on the microstructure and tensile properties of an unmodified A356-T6 cast aluminum alloy. Journal of Alloys and Compounds, 2006, 42(1~2): 80-86.
[19] Atxaga G, Pelayo A, Irisarri A M. Effect of microstructure on fatigue behaviour of cast Al-7Si-Mg alloy. Materials Science and Technology, 2001, 17(4): 446-450.
[20] Lados D A, Apelian D. Fatigue crack growth characteristics in cast Al-Si-Mg alloys Part I. Effect of processing conditions and microstructure. Materials Science and Engineering A, 2004, 385: 200.
[21] Seniw M E, Conley J G. The effect of microscopic inclusion locations and silicon segregation on fatigue lifetimes of aluminum alloy A356 castings. Materials Science and Engineering A, 2000, 285: 438.
[22] Wang Q G, Apelian D, Lados D A. Fatigue behavior of A356-T6 aluminum cast alloys. Part I - Effect of casting defects. Journal of Light Metals, 2001, 1(1): 73-84.
[23] Boileau J M, Allison J E. The effect of solidification time and heat treatment on the fatigue properties of a cast 319 aluminum alloy. Metallurgical and Materials Transactions A, 2003, 34 (9): 1807-1820.
[24] Bray G H, Glazov M, Rioja R J, et al. Effect of artificial aging on the fatigue crack propagation resistance of 2000 series aluminum alloys. International Journal of Fatigue, 2001, 23 (S): 265-276.
[25]杨平生,刘炎,张萌,等.纯铝和铝合金的低周冲击疲劳行为.南昌大学学报(理科版), 1996, 20(2): 156-160.
[26]王莉,蒋大鸣.时效对6063铝合金力学性能及阻尼特性的影响.轻合金加工技术, 2003, 31(12): 35-37.
[27]周敬恩,冉广. A356铸造铝合金的疲劳裂纹萌生及短裂纹扩展研究.金属热处理, 2008, 33(1): 34-42.
[28]朱正宇,何国求,陈成澍. ZL101铝合金低周疲劳行为研究.特种铸造及有色合金, 2007, 27(4): 256-260.
[29]刘延斌,刘志义,李云涛,等.时效对2524铝合金热稳定性的影响.材料研究学报, 2007, 21(6): 585-588.
[30]李海,郑子樵,魏修宇,等.时效析出对2E12铝合金疲劳断裂行为的影响.中国有色金属学报, 2008, 18(4): 589-594.
[31]莫德锋,何国求,朱正宇,等. Al-7Si-0.3Mg合金低周疲劳行为及其机理.特种铸造及有色合金, 2008, 28(7): 493-496.
[32]李晗. 2024铝合金薄板的热处理工艺与性能研究: (硕士学位论文).西安:西北工业大学, 2007.
[33]董显娟.时效制度对7B04铝合金组织与性能的影响: (硕士学位论文).长沙:中南大学, 2004.
[34]沈华龙,吴运新,熊卫民.振动时效应用于铝合金时动应力的选择.材料工程, 2009 (4): 18-22
[35] SHIPILOV S A.腐蚀疲劳裂纹扩展的机理.中国腐蚀与防护学报, 2004, 24(6): 321-333.
[36]何建平. NaCl电解液薄层下LC4CS铝合金腐蚀疲劳性能.南京航空航天大学学报, 2004, 36(4): 412-416.
[37]郑晓玲.民机结构耐久性与损伤容限设计手册(下册).北京:航空工业出版社, 2003.
[38]秦剑波,王生楠,刘亚龙,等.腐蚀环境下2024-T3铝合金疲劳裂纹扩展和剩余强度实验研究.材料工程, 2006 (3): 14-17.
[39] Congleton J, Charles E A. Review on effect of cyclic loadinon environmental assisted cracking of alloy 600 in typicanuclear coolant waters. Corrosion Science, 2001, 43: 2265-2279.
[40]刘祖铭,曾凡阳,鲁礼菊,等.环境对LY12CZ铝合金典型螺接件疲劳性能的影响.中国腐蚀与防护学报, 2004, 24(5): 267-271.
[41]鲍蕊,张建宇,费斌军.潮湿空气环境对2024-T3铝合金疲劳性能的影响.材料研究学报, 2007, 21(5): 547-550.
[42]杨胜,易丹青,杨守杰,等.腐蚀环境下2E12航空铝合金疲劳裂纹扩展行为研究.材料工程, 2007 (12): 26-34.
[43]钱建刚,李荻,郭宝兰,等. LC4高强铝合金的腐蚀性能研究.腐蚀与防护, 2002, 23(8): 340-343.
[44]向磊,刘培英,周铁涛.采用自制简易装置评定高强铝合金的应力腐蚀性能.物理测试, 2005, 23(5): 32-35.
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