Improved creep aging response in Al-Cu alloy by applying pre-aging before pre-straining  

作　　者：Fangpu LYU Chunhui LIU Peipei MA Jianshi YANG Longhui CHEN Lihua ZHAN Minghui HUANG 

机构地区：[1]State Key Laboratory of Precision Manufacturing for Extreme Service Performance,School of Mechanical and Electrical Engineering,Central South University,Changsha 410083,China [2]Light Alloy Research Institute,Central South University,Changsha 410083,China [3]Advanced Research Center,Central South University,Changsha 410083,China

出　　处：《Chinese Journal of Aeronautics》2023年第7期518-530,共13页中国航空学报（英文版）

基　　金：support from the National Natural Science Foundation of China(Nos.52274404,U2032117,U22A20190);Natural Science Foundation of Hunan Province,China(No.2022JJ20065);the Science and Technology Innovation Program of Hunan Province,China(No.2022RC1001);the National Key Research and Development Program of China(No.2021YFB3400903).

摘　　要：The improvement of post-form properties without compromising creep formability has been a critical issue in creep age forming of aluminum alloy component. A pretreatment process incorporating artificial pre-aging at 165 °C for 6 h/12 h/24 h followed by pre-strain(3%–9%)has been developed. This method not only evidently improves the strength but also accelerates the creep deformation during creep aging of an Al-Cu alloy. A strength increase of 50 MPa with a slight decrease of ductility relative to the 9% pre-strained alloy is acquired in the alloy artificially pre-aged for 24 h regardless of the pre-strain level(3%–9%). Artificial aging for 24 h prior to 3%pre-strain enables an increase of creep strain by 30%. The creep strain in the alloy artificially preaged for 24 h and pre-strained by 6% is comparable to that in the alloy pre-strained by 9%. The strength and ductility in the alloy artificially pre-aged for 6 h/12 h and pre-strained by 3% are even slightly higher than those in the alloy purely pre-strained by 9%. The characterizations by transmission electron microscopy reveal that pre-aging at 165 °C could promote the accumulation of dislocations during pre-straining due to the pinning effect of pre-existing Guinier-Preston zones(GP zones)/θ’’phases and thus expedite the creep deformation in respect to the pure pre-straining treatment. The enhanced precipitation of θ’phases at these pinned dislocations contributes to the improved strength after creep aging. The results demonstrate applying artificial pre-aging before pre-straining is an efficient strategy to elevate the creep aging response in Al alloys.

关 键 词：Al-Cu alloy Creep aging PRE-AGING PRECIPITATION PRE-STRAIN 

分 类 号：TG156.92[金属学及工艺—热处理] TG146.21[金属学及工艺—金属学] V252.2[一般工业技术—材料科学与工程]