175℃热暴露对7A99铝合金微观组织与力学性能的影响

高文林; 李成龙; 孙进宝; 刘惠; 虞朝智; 马正斌; 陆政

doi:10.15980/j.tzzz.2020.07.021

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175℃热暴露对7A99铝合金微观组织与力学性能的影响
Effects of 175℃ Heat Exposure Treatment on the Microstructure and Mechanical Properties of 7A99 Aluminum Alloy
2020年40卷第7期页码：784-787
纸质出版日期： 2020 ，
DOI： 10.15980/j.tzzz.2020.07.021

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[1]高文林,李成龙,孙进宝,刘惠,虞朝智,马正斌,陆政.175℃热暴露对7A99铝合金微观组织与力学性能的影响[J].特种铸造及有色合金,2020,40(07):784-787.

Gao Wenlin, Li Chenglong, Sun Jinbao, et al. Effects of 175℃ Heat Exposure Treatment on the Microstructure and Mechanical Properties of 7A99 Aluminum Alloy[J]. Special Casting & Nonferrous Alloys, 2020,40(7):784-787.
[1]高文林,李成龙,孙进宝,刘惠,虞朝智,马正斌,陆政.175℃热暴露对7A99铝合金微观组织与力学性能的影响[J].特种铸造及有色合金,2020,40(07):784-787. DOI： 10.15980/j.tzzz.2020.07.021.

Gao Wenlin, Li Chenglong, Sun Jinbao, et al. Effects of 175℃ Heat Exposure Treatment on the Microstructure and Mechanical Properties of 7A99 Aluminum Alloy[J]. Special Casting & Nonferrous Alloys, 2020,40(7):784-787. DOI： 10.15980/j.tzzz.2020.07.021.

摘要

通过XRD、TEM与室温拉伸等测试分析手段

研究了在175℃下50、100h热暴露处理对T6态7A99铝合金微观组织与力学性能的影响。结果表明

经过175℃下50、100h热暴露处理后

7A99铝合金晶内析出相种类未发生变化

析出相仍然以η′相和η相为主。175℃热暴露处理后

7A99铝合金晶内析出相由η′相向η相发生转变

η相尺寸长大、密度降低、晶界无析出带显著增宽。T6态7A99铝合金的抗拉强度为505MPa、屈服强度为406 MPa、伸长率为12%;经175℃×50h热暴露处理后其抗拉强度为330MPa、屈服强度为250MPa

分别较T6态降低了34.7%和38.4%

而伸长率升至16.8%

较T6态提高40%;经175℃×100h热暴露处理后合金的抗拉强度为305MPa、屈服强度为225MPa

分别较T6态降低了39.6%和44.6%

而伸长率升高到20%

较T6态提高了66.7%。175℃热暴露处理后7A99铝合金强度降低主要是热暴露过程中大量半共格的η′相转变成为非共格的η相

导致铝基体晶格畸变程度显著降低。

Abstract

The effects of heat exposure treatment at 175℃for 50 hand 100 hon the microstructure and mechanical properties of T6-7A99 alloy were investigated by means of X-ray diffraction

transmission electron microscopy and room temperature tensile testing.The results reveal that the precipitate phases in the 7A99 alloy still consist ofη′andηphases after being exposured at 175℃for 50 hand 100 h.Theη′phases in the grains are transformed intoηphases at 175℃for 50 hand 100 hheat exposure treatment

meanwhile the size of precipitate phase is increased with the decrease of density of precipitate phases and the increase of PFZ width.The tensile strength

yield strength and elongation of 7A99 alloy treated by T6 reach 505 MPa

406 MPa and 12%

respectively

while those of ones exposured at 175℃for 50 hare 330 MPa

250 MPa and 16.8%

and those of T6-7A99 alloy exposured at 175℃for 100 hare 305 MPa

225 MPa and 20%

respectively.The mechanism is attributed to theηphases transformed fromη′phases reducing the distoration of the lattice severely.