摘要
通过硬度测试、室温拉伸测试、电子背散射衍射分析(EBSD)、透射电子显微分析(TEM)以及数字图像相关(DIC)等手段,研究不同拉伸预变形量对2195铝锂合金在155℃时效后拉伸力学性能的影响。结果表明:拉伸预变形量为2%、4%、6%、8%的合金经过155℃时效后,其抗拉强度分别为560.4 MPa、570.8 MPa、573.6 MPa、575.9 MPa。随着预变形量的增大,合金强度不断提高,这是由于位错是强化相T1相的有利形核点位,拉伸预变形量的增大使得位错密度增加,从而使得T1相数量密度增加。但随着拉伸预变形量的增大,拉伸预变形对合金的强度提升幅度逐渐减小,这主要是位错堆积缠结,析出相形核点重叠导致的。随着拉伸预变形量从2%增大到8%,合金的伸长率从9.6%下降到6.4%。通过DIC观察,拉伸预变形量的增大会使得拉伸过程中的应变集中现象提前出现,颈缩稳定性有所降低。这是由于较大的拉伸预变形量会使得合金在预变形阶段的应变分布不均匀,合金内出现破碎的变形组织晶粒。这些变形组织晶粒与周围其他晶粒组织的晶粒取向不同,更有利于微裂纹的萌生和扩展。4%的拉伸预变形量可以使2195铝锂合金达到最佳的强塑性匹配,此时抗拉强度为570.8 MPa、屈服强度为543.4 MPa、伸长率为8.7%。
The effects of different stretching pre-strains on the tensile mechanical properties of 2195 aluminum-lithium alloy after aging at 155℃were studied by hardness test,room temperature tensile test,electron backscatter diffraction analysis(EBSD),transmission electron microscopy(TEM)and digital image correlation(DIC).The results show that the ultimate tensile stresses at the stretching pre-strain of 2%,4%,6%and 8%are 560.4 MPa,570.8 MPa,573.6 MPa and 575.9 MPa.With the increase of stretching pre-strain,the strength of the alloy continues to increase,which is because the dislocation is a favorable nucleation point for the strengthened phase T1 phase,and the increase of stretching pre-strain increases the dislocation density and the number density of T1 phase.However,with the increase of stretching pre-strain,the strength increase amplitude of stretching pre-strain on the alloy gradually decreases,which is mainly caused by entanglement and accumulation of dislocation and precipitation of phase nucleation points.As the stretching pre-strain increases from 2%to 8%,the elongation of the alloy decreases from 9.6%to 6.4%.It can be observed that the increase of stretching pre-strain makes the strain concentration phenomenon in the tensile process advance and the necking stability decreases by digital image correlation.This is due to the large stretching pre-strain will cause the strain distribution of the alloy in the stretching pre-strain to be uneven,and broken deformation microstructure grains appear in the alloy.The grain orientation of these deformation microstructure grains are different from other grain around them,which is more conducive to the initiation and propagation of microcracks.Therefore,considering the tensile mechanical properties of 2195 aluminum-lithium alloy under different stretching pre-strain,4%stretching pre-strain can make 2195 aluminum-lithium alloy achieve the best strong plastic matching,with ultimate tensile stress of 570.8 MPa,yield stress of 543.4 MPa and elongation of 8.7%.
作者
张翼飞
叶凌英
董宇
邹国童
李俊
杨献文
ZHANG Yifei;YE Lingying;DONG Yu;ZOU Guotong;LI Jun;YANG Xianwen(School of Material Science and Engineering,Central South University,Changsha 410083,China;Key Laboratory of Nonferrous Metal Materials Science and Engineering,Ministry of Education,Central South University,Changsha 410083,China)
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2024年第3期725-738,共14页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(U21A20130)。
关键词
2195铝锂合金
拉伸预变形
拉伸力学性能
数字图像相关
应变集中现象
2195 Al-Li alloy
stretching pre-strain
tensile mechanical properties
digital image correlation
strain concentration phenomenon
