Microstructure and Mechanical Properties of Extruded and Aged EW75-0.7 Al Alloy

Pu Zhijun; Zhang Guodong; Li Xinggang; Ma Minglong; Li Yongjun; Shi Guoliang; Yuan Jiawei; Zhang Kui

doi:10.15980/j.tzzz.2014.10.008

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Microstructure and Mechanical Properties of Extruded and Aged EW75-0.7 Al Alloy
Vol. 34, Issue 10, Pages: 1039-1042(2014)
Published： 2014 ，
DOI： 10.15980/j.tzzz.2014.10.008

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[1]蒲治军,张国栋,李兴刚,马鸣龙,李永军,石国梁,袁家伟,张奎.EW75-0.7Al合金挤压、时效态的组织及力学性能[J].特种铸造及有色合金,2014,34(10):1039-1042.

Pu Zhijun, Zhang Guodong, Li Xinggang, et al. Microstructure and Mechanical Properties of Extruded and Aged EW75-0.7 Al Alloy. [J]. Special Casting & Nonferrous Alloys 34(10):1039-1042(2014)
[1]蒲治军,张国栋,李兴刚,马鸣龙,李永军,石国梁,袁家伟,张奎.EW75-0.7Al合金挤压、时效态的组织及力学性能[J].特种铸造及有色合金,2014,34(10):1039-1042. DOI： 10.15980/j.tzzz.2014.10.008.

Pu Zhijun, Zhang Guodong, Li Xinggang, et al. Microstructure and Mechanical Properties of Extruded and Aged EW75-0.7 Al Alloy. [J]. Special Casting & Nonferrous Alloys 34(10):1039-1042(2014) DOI： 10.15980/j.tzzz.2014.10.008.

摘要

通过OM、SEM、硬度及拉伸等测试手段

研究了EW75-0.7Al合金挤压及时效态的组织和力学性能。结果表明

挤压后合金晶粒明显细化

室温力学性能显著提高

抗拉强度为330MPa

屈服强度为242MPa

伸长率为11%。通过对合金进行T5时效处理

确定EW75-0.7Al合金的最佳T5峰时效制度为225℃×12h

经过T5峰时效处理后

合金的室温强度相比挤压态提高约100MPa。T5峰时效态合金在200℃高温下

力学性能下降不明显

在250℃高温下力学性能显著降低。通过分析合金高温下的断裂方式

发现250℃高温下

EW75-0.7Al合金的晶界强度显著降低

且时效析出相与基体的结合能力下降

最终导致合金在该温度下力学性能明显降低。

Abstract

The microstructure and mechanical properties of extruded and aged state EW75-0.7Al alloy were investigated by OM

SEM

hardness and tensile testing methods.The results reveal that grain in the extruded alloy is refined obviously

and mechanical properties

such as tensile strength

yield strength and elongation

are improved significantly at room temperature to 330 MPa

242MPa and 11%

respectively.By observing T5 aging treatment of EW75-0.7Al alloy

the optimal T5 peak aging parameter is at 225℃for 12 h.The T5peak-aged alloy exhibits the better tensile strength than extruded alloy at room temperature

increased by approximately 100 MPa.At 200℃

the mechanical properties are decreased slightly

however

they are deteriorated significantly at 250℃.By analyzing the fracture mode under 250℃

it is found that grain boundary strength of EW75-0.7Al alloy is weakened greatly

and the bonding strength between precipitation and matrix are also decreased

which are responsible for the decrease of the strength of the alloy at 250℃.