加载方向对Al-Zn-Mg合金型材应力腐蚀开裂行为的影响

吴建山; 邓运来; 张臻; 张议丹; 孙琳

doi:10.13374/j.issn2095-9389.2019.03.008

加载方向对Al-Zn-Mg合金型材应力腐蚀开裂行为的影响

doi: 10.13374/j.issn2095-9389.2019.03.008

吴建山^1,3,
邓运来^1,2,3,
张臻^2,3, ,,
张议丹^1,3,
孙琳⁴

1) 中南大学材料科学与工程学院, 长沙 410083
2) 中南大学轻合金研究院, 长沙 410083
3) 中南大学有色金属先进结构材料与制造协同创新中心, 长沙 410083
4) 中车青岛四方机车车辆股份有限公司, 青岛 266000

基金项目:

国家自然科学基金资助项目(51375503)

国家重点研发计划资助项目(2016YFB0300901)

国家重点基础研究发展计划资助项目(2012CB619500)

详细信息

中图分类号: TG146.2;TG113
计量
- 文章访问数: 477
- HTML全文浏览量: 114
- PDF下载量: 6
- 被引次数: 0
出版历程
- 收稿日期: 2018-08-19

Effect of sampling direction on the stress corrosion cracking behavior of Al-Zn-Mg alloy

WU Jian-shan^1,3,
DENG Yun-lai^1,2,3,
ZHANG Zhen^{2,3
, ,},
ZHANG Yi-dan^1,3,
SUN Lin⁴

1) School of Materials Science and Engineering, Central South University, Changsha 410083, China
2) Light Alloy Research Institute, Central South University, Changsha 410083, China
3) Cooperative Innovation Center for Advanced Nonferrous Metal Structural Materials and Manufacturing, Central South University, Changsha 410083, China
4) CRRC Qingdao Sifang Co., Ltd., Qingdao 266000, China

摘要

摘要: 采用恒载荷拉伸应力腐蚀试验和电化学试验研究取向对Al-Zn-Mg合金型材的应力腐蚀(SCC)开裂的影响,腐蚀介质采用质量分数3.5%的NaCl溶液,容器温度维持在50±2℃,并通过光学金相显微镜(OM)、扫描电子显微镜(SEM)、电子背散射衍射(EBSD)等研究不同取向试样应力腐蚀前、后的微观形貌.结果表明横向试样在315 h时断裂,而纵向试样在整个加载过程中未发生断裂,纵向试样有更好的抗应力腐蚀开裂性能;纵截面(L-S面)的腐蚀电流密度为0.980 mA·cm^-2,约为横截面(T-S面)的5倍,腐蚀倾向于沿挤压方向发展;相比T-S面,L-S面晶粒间取向差较大,大角度晶界多,容易被腐蚀产生裂纹;在应力腐蚀加载过程中,试样先发生阳极溶解,形成腐蚀坑,聚集的腐蚀产物所产生的楔入力和恒定载荷的共同作用促使裂纹在腐蚀介质中加速扩展,两种取向试样均发生了明显的晶间腐蚀,存在应力腐蚀开裂的倾向.
- Al-Zn-Mg合金 /
- 取样方向 /
- 应力腐蚀开裂 /
- 阳极溶解 /
- 晶间腐蚀
Abstract: Thick-section Al-Zn-Mg aluminum alloy extrusions are key materials for manufacturing rail transit vehicles, and stress corrosion cracking (SCC) is an important engineering application problem during the service life of these materials. The effect of sampling direction on the stress corrosion cracking behavior of Al-Zn-Mg alloys was investigated through constant load tensile stress corrosion and electrochemical tests. The microstructures of specimens were analyzed in different sampling directions both before and after stress corrosion via optical microscopy, scanning electron microscopy, and electron backscatter diffraction. Specimens with their tensile axes parallel or perpendicular to the extrusion direction of the extruded profiles were labeled as longitudinal specimens and transverse specimens, respectively. The specimens were completely immersed in a corrosive solution, a mixture of 35 g NaCl and 1 L deionized water, with a constant unidirectional loading of 225 MPa for 360 h at 50 ±2℃. The experimental results show that the transverse specimen is fractured at 315 h, whereas the longitudinal specimen does not break during the entire loading process. Thus, the transverse specimens have poor resistance to stress corrosion cracking. The corrosion current density of the longitudinal section (L-S) is 0.980 mA·cm^-2, which is approximately 5 times that of the transverse section (T-S). Thus, corrosion tends to propagate along the longitudinal direction. The L-S is more susceptible to corrosion than the T-S owing to the larger misorientation difference and higher energy of the grain boundary. During the stress corrosion loading process, anodic dissolution occurs and forms corrosion pits. Then, the cooperation of the wedge force produced by the accumulation of corrosion products and constant load causes the crack to propagate along the grain boundary. Intergranular corrosion of the two types of samples is obvious under all immersion corrosion conditions. Different specimens exhibit the tendency to undergo stress corrosion cracking.
- Al-Zn-Mg alloy /
- sampling direction /
- stress corrosion cracking /
- anodic dissolution /
- intergranular corrosion

HTML全文

参考文献(14)

[6]	Braun R. Environmentally assisted cracking of aluminum alloys. Materialwiss Werkstofftech, 2007, 38(9):674
[9]	Jha A K, Murty S V S N, Diwakar V, et al. Metallurgical analysis of cracking in weldment of propellant tank. Eng Fail Anal, 2003, 10(3):265
[10]	Rao A C U, Vasu V, Govindaraju M, et al. Stress corrosion cracking behaviour of 7xxx aluminum alloys:a literature review. Trans Nonferrous Met Soc China, 2016, 26(6):1447
[11]	Oñoro J. The stress corrosion cracking behaviour of heat-treated Al-Zn-Mg-Cu alloy in modified salt spray fog testing. Mater Corros, 2010, 61(2):125
[12]	Heinz A, Haszler A, Keidel C, et al. Recent development in aluminium alloys for aerospace applications. Mater Sci Eng A, 2000, 280(1):102
[13]	Chen K H, Huang L P. Strengthening toughening of 7xxx series high strength aluminum alloys by heat treatment. Trans Nonferrous Met Soc China, 2003, 13(3):484
[15]	Lee E U, Taylor R, Lei C, et al. Stress corrosion cracking of aluminum alloys. Metall Trans A,1975, 6(4):631
[16]	Xiao Y P, Pan Q L, Li W B, et al. Influence of retrogression and re-aging treatment on corrosion behaviour of an Al-Zn-Mg-Cu alloy. Mater Des, 2011, 32(4):2149
[17]	Wang D, Ma Z Y. Effect of pre-strain on microstructure and stress corrosion cracking of over-aged 7050 aluminum alloy. J Alloys Compd, 2009, 469(1-2):445
[18]	Rometsch P A, Zhang Y, Knight S. Heat treatment of 7xxx series aluminium alloys-Some recent developments. Trans Nonferrous Met Soc China, 2014, 24(7):2003
[19]	Speidel M O. Stress corrosion cracking of aluminum alloys. Metall Trans A, 1975, 6(4):631
[20]	Fang H C, Chao H, Chen K H. Effect of recrystallization on intergranular fracture and corrosion of Al-Zn-Mg-Cu-Zr alloy. J Alloys Compd, 2015, 622:166
[22]	Shi Y J, Pan Q L, Li M J, et al. Effect of Sc and Zr additions on corrosion behaviour of Al-Zn-Mg-Cu alloys. J Alloys Compd, 2014, 612:42
[25]	Viswanadham R K, Sun T S, Green J A S. Grain boundary segregation in Al-Zn-Mg alloys-Implications to stress corrosion cracking. Metall Mater Trans A, 1980, 11(1):85