Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第28卷    第10期    总第235期    2018年10月

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文章编号:1004-0609(2018)-10-1999-10
时效对固溶+冷轧7075铝合金力学性能和显微组织的影响
李 海1, 2,陈 鹏1,王芝秀1, 2,郑子樵3

(1. 常州大学 材料科学与工程学院,常州 213164;
2. 常州大学 江苏省材料表面科学与技术重点实验室,常州 213164;
3. 中南大学 材料科学与工程学院,长沙 410083
)

摘 要: 采用拉伸测试、金相显微镜、XRD及TEM等方法,研究时效处理对经历固溶+冷轧的7075铝合金显微组织和力学性能的影响规律。力学性能测试表明:80、100、120 ℃时效均能显著提高合金强度并保持一定塑性。(475 ℃, 1 h固溶处理)+80%压下量冷轧+(80 ℃, 48 h)时效合金的抗拉强度、屈服强度和伸长率分别为773 MPa、720 MPa和5%。显微组织分析表明:相较于冷轧合金,时效合金强度的提高源于冷轧加工硬化(高的位错密度、高的轧制织构体积分数及细化的晶粒尺寸)和析出强化的共同作用;时效合金伸长率的改善与位错回复程度和析出相特征同时相关。此外,根据时效析出和位错回复特征,分析了时效过程中合金强度和伸长率的变化规律。

 

关键字: 7075铝合金;形变热处理;显微组织;力学性能

Effect of ageing on mechanical properties and microstructures of solution treated and cold-rolled 7075 Al alloy
LI Hai1, 2, CHEN Peng1, WANG Zhi-xiu1, 2, ZHENG Zi-qiao3

1. School of Materials Science and Engineering, Changzhou University, Changzhou 213164, China;
2. Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164, China;
3. School of Materials Science and Engineering, Central South University, Changsha 410083, China

Abstract:The effects of ageing at 80, 100 and 120 ℃ on the mechanical properties and microstructures of 7075 Al alloy solution treated at 475 ℃ for 1 h and cold-rolled at room temperature by thickness reduction of 80% were studied by tensile test, optical microscopy, X-ray diffractometry (XRD) and transmission electron microscopy (TEM). Tensile test results show that the strength of the alloy is significantly improved by the thermomechanical treatment with acceptable ductility. Especially, after being aged at 80 ℃ for 48 h, the ultimate tensile strength, yield strength and elongation to failure of the alloy are 773 MPa, 720 MPa and 5%, respectively. Microstructural observations show that the strength of the alloy is attributed to the combination of cold-rolling work hardening (high dislocation density, increased rolling textures and refined grains) and precipitation strengthening. Meanwhile, the improved elongation of the alloy is mainly due to dislocation recovery and ageing precipitation. Furthermore, the change in strength and ductility of the alloy during ageing was analyzed further based on the dislocation density and precipitation characterization.

 

Key words: 7075 aluminum alloy; thermomechanical treatment; microstructure; mechanical property

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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