Influence of pre-stretching on the tensile strength,fatigue properties and the in-plane anisotropy in Al-Cu-Li alloy AA2099  

作　　者：Xianghui Zhu Xusheng Yang Weijiu Huang Weiyi Qiu Xin Wang Fei Guo Li Hu Miao Gong 

机构地区：[1]College of Materials Science and Engineering,Kunming University of Science and Technology,Kunming 650093,China [2]College of Materials Science and Engineering,Chongqing University of Arts and Sciences,Chongqing 402160,China [3]College of Materials Science and Engineering,Chongqing University of Technology,Chongqing 400044,China

出　　处：《Journal of Materials Science & Technology》2023年第14期249-259,共11页材料科学技术（英文版）

基　　金：This work is financially supported by the National Science Foun-dation of China(No.51871038);the Basic Research and Frontier Exploration Project of Chongqing Science and Technology Com-mission(No.cstc2021ycjh-bgzxm0173);the Basic Research and Frontier Exploration Project of Chongqing Science and Technology Commission(No.cstc2021ycjh-bgzxm0175)。

摘　　要：The influence of pre-stretching prior to artificial aging on microstructure,tensile properties,and fatigue behavior of AA2099-T8 sheets was investigated.The results showed that increased pre-strain level from 1%to 6%resulted in a more uniform distribution and increasing density of the T_(1)phase.The localized plastic deformation during pre-stretching led to the formation of dense precipitation bands(DPBs)and precipitation free bands(T_(1)-PFBs)in the sheets with the 1%pre-strain.The non-uniform distribution of the T_(1)phase with T_(1)-PFBs and DPBs resulted in a decrement in elongation and a strong in-plane anisotropy of tensile properties.An appropriate level of pre-strain should be executed aiming to improve elongation and reduce the tensile anisotropy by promoting a uniform distribution of the T_(1)phase.In-plane anisotropy of yield strength due to the presence of DPBs and T_(1)-PFBs was quantitatively analyzed by the modified Hall-Petch formula.The results of the calculation for the modified model showed good agreement with the experiment.In addition,resistances of fatigue crack propagation(FCP)in the same orientation were gradually decreased with the increment of pre-strain due to the increment in yield strength and more uniform distribution of the T_(1)phase.For the in-plane anisotropy of FCP resistance,the main reasons were the development of rough fracture surfaces and the transgranular fracture modes in L-T orientation.

关 键 词：Aluminum-lithium alloys PRECIPITATION Mechanical properties Fatigue crack propagation 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG335.11[金属学及工艺—金属材料]