Research on stress corrosion crack failure of MIG joints on aluminum alloy of high-speed trains

doi:10.16265/j.cnki.issn1003-3033.2022.06.2061

Abstract

Abstract:

In order to improve service safety of high-speed trains and explore stress corrosion cracking fracture mechanism of welded joints, microstructure, mechanical properties, and stress corrosion cracking properties of MIG welding joints of 6005A aluminum alloy were investigated by adopting optical microscopy, transmission electron microscope (TEM), scanning electron microscope (SEM), hardness test, tensile test, constant stress corrosion load test and so on. The results show that under the effect of welding heat, intragranular precipitates is coarsened and redissolved in heat affected zone (HAZ), and precipitation free zone (PFZ) is widened at grain boundary. Hardness distribution of the joints is "W" type, with minimal-hardness point located in HAZ zone, and MIG joints also fracture at HAZ zone in room temperature tensile test and constant load stress corrosion test. Along with the increase of loading stress, stress corrosion cracking sensitivity will increase, and intergranular stress corrosion cracking failure fracture will accelerate. And average fracture time of the joints reaches about 42 h under high load stress (0.9 R_p_0.2).

Key words: high-speed trains, 6005A aluminum alloy, metal-inert gas (MIG) welding, microstructure, mechanical property

LIN Sen, HAN Xiaohui, LI Gangqing, WANG Peng, ZHAO Cunjin, YANG Zhibin. Research on stress corrosion crack failure of MIG joints on aluminum alloy of high-speed trains[J]. China Safety Science Journal, 2022, 32(6): 115-122.

Figures/Tables 9

Tab.1

Fig.1

Fig.2

Fig.3

Tab.2

Room temperature tensile properties of 6005A-T5 aluminum alloy and MIG joints

试样	R_m/MPa	$R p 0.2$ /MPa	A₅₀/%	焊接系数/%
母材	289.1±3.3	247.8±3.8	13.6±0.4	—
接头	199.3±2.9	131.9±3.1	8.9±0.5	68.9

Tab.2

Fig.4

Fig.5

Tab.3

Fig.6

References 17

[1]	向雪梅, 赖玉香, 刘春辉, 等. 微合金化元素Sn对Al-Mg-Si合金高温时效强化相析出路径的改变[J]. 金属学报, 2018, 54(9): 1273-1280. doi: 10.11900/0412.1961.2018.00125
	XIANG Xuemei, LAI Yuxiang, LIU Chunhui, et al. Sn-induced modification of the precipitation pathways upon high-temperature ageing in an Al-Mg-Si alloy[J]. Acta Metallurgica Sinica, 2018, 54(9): 1273-1280. doi: 10.11900/0412.1961.2018.00125
[2]	ZHANG Xinxin, ZHOU Xiaorong, NILSSON J. Corrosion behaviour of AA6082 Al-Mg-Si alloy extrusion: the influence of quench cooling rate[J]. Corrosion Science, 2019, 150: 100-109. doi: 10.1016/j.corsci.2019.01.030
[3]	TEICHMANN K, MARIOARA C D, ANDERSEN S J, et al. TEM study of β' precipitate interaction mechanisms with dislocations and β' interfaces with the aluminium matrix in Al-Mg-Si alloys[J]. Materials Characterization, 2013, 75: 1-7. doi: 10.1016/j.matchar.2012.10.003
[4]	张鑫. 高速列车用6系铝合金应力腐蚀性能研究[D]. 南京: 南京理工大学, 2016.
	ZHANG Xin. The stress corrosion behavior investigation of 6 series aluminum alloy for high-speed train[D]. Nanjing: Nanjing University of Science & Technology, 2016.
[5]	吕伟, 秦霜霜, 穆治国, 等. CRH380AL型高铁列车应急疏散及影响因素模拟研究[J]. 中国安全科学学报, 2020, 30(8):164-170. doi: 10.16265/j.cnki.issn1003-3033.2020.08.024
	LYU Wei, QIN Shuangshuang, MU Zhiguo, et al. Simulation study on evacuation of CRH380AL high-speed train and its influencing factors[J]. China Safety Science Journal, 2020, 30(8): 164-170. doi: 10.16265/j.cnki.issn1003-3033.2020.08.024
[6]	赵江平, 徐恒, 党悦悦. 基于改进Faster R-CNN的铁路客车螺栓检测研究[J]. 中国安全科学学报, 2021, 31(7):82-89. doi: 10.16265/j.cnki.issn 1003-3033.2021.07.012
	ZHAO Jiangping, XU Heng, DANG Yueyue. Research on bolt detection of railway passenger cars based on improved Faster R-CNN[J]. China Safety Science Journal, 2021, 31(7): 82-89. doi: 10.16265/j.cnki.issn 1003-3033.2021.07.012
[7]	吉华, 邓运来, 邓建峰, 等. 焊接速度对6005A-T6铝合金双轴肩搅拌摩擦焊接头力学性能的影响[J]. 焊接学报, 2019, 40(5):24-29.
	JI Hua, DENG Yunlai, DENG Jianfeng, et al. Effect of welding speed on mechanical properties of double-shaft shoulder friction stir welding joint of 6005A-T6 aluminum alloy[J]. Transactions of the China Welding Institution, 2019, 40(5):24-29.
[8]	张昱, 李冀东, 丁鑫健, 等. 6N01铝合金高频脉冲电流复合MIG焊接电信号和图像信号的采集与分析[J]. 热加工工艺, 2020, 49(1):152-154.
	ZHANG Yu, LI Jidong, DING Xinjian, et al. Acquisition and analysis of electric signals and image signals of high frequency pulse current hybrid MIG welding of 6N01 aluminum alloy[J]. Hot Working Technology, 2020, 49(1):152-154.
[9]	孟立春, 刘春辉, 赖玉香, 等. 6N01-7N01铝合金T型焊接接头的微观组织与性能的研究[J]. 湖南大学学报:自然科学版, 2017, 44(12):20-26.
	MENG Lichun, LIU Chunhui, LAI Yuxiang, et al. The heterogeneity in microstructure and property of the welded joints between 6N01 and 7N01 aluminum alloy[J]. Journal of Hunan University:Natural Science, 2017, 44(12):20-26.
[10]	GB/T 228.1—2010, 金属材料拉伸试验第1部分:室温试验方法[S].
	GB/T 228.1—2010, Metallic materials-tensile testing part 1: method of test at room temperature[S].
[11]	HB 5254—1983, 变形铝合金拉伸应力腐蚀.试验方法[S].
[12]	LIN Sen, DENG Yunlai, LIN Huaqiang, et al. Microstructure, mechanical properties and stress corrosion behavior of friction stir welded joint of Al-Mg-Si alloy extrusion[J]. Rare Metals, 2018: doi: 10.1007/s12598-018-1126-7. doi: 10.1007/s12598-018-1126-7
[13]	ZHANG Liang, LI Xiaoyan, NIE Zuoren, et al. Microstructure and mechanical properties of a new Al-Zn-Mg-Cu alloy joints welded by laser beam[J]. Materials & Design, 2015, 83: 451-458.
[14]	CHU Qiaoling, BAI Ruixiang, JIAN Haigen, et al. Microstructure, texture and mechanical properties of 6061 aluminum laser beam welded joints[J]. Materials Characterization, 2018, 137: 269-276. doi: 10.1016/j.matchar.2018.01.030
[15]	YANG Wenchao, JI Shouxun, ZHANG Qian, et al. Investigation of mechanical and corrosion properties of an Al-Zn-Mg-Cu alloy under various ageing conditions and interface analysis of η' precipitate[J]. Materials & Design, 2015, 85: 752-761.
[16]	LIN Y C, ZHANG Jinlong, LIU Guan, et al. Effects of pre-treatments on aging precipitates and corrosion resistance of a creep-aged Al-Zn-Mg-Cu alloy[J]. Materials & Design, 2015, 83: 866-875.
[17]	LI Hai, ZHAO Peipei, WANG Zhixiu, et al. The intergranular corrosion susceptibility of a heavily overaged Al-Mg-Si-Cu alloy[J]. Corrosion Science, 2016, 107: 113-122. doi: 10.1016/j.corsci.2016.02.025

加载应力/ MPa	剩余强度/ MPa	剩余强度系数/%	强度损失率/%
90(约0.7 R_p_0.2)	131.6±8.9	68.6±4.6	31.4±4.6
105 (约0.8 R_p_0.2)	85.6±15.5	44.6±8.1	55.4±8.1
120 (约0.9 R_p_0.2)	—	—	—