Effects of pre-rolling on mechanical properties and fatigue crack growth rate of 2195 Al-Li alloy  

预变形对2195铝锂合金力学性能及疲劳裂纹扩展速率的影响

作　　者：CHEN Meng-xi LI Yi-bo XIA Lin-yan HUANG Ming-hui WU Zhen-yu YANG Yi QU Zi-jing 陈梦喜;李毅波;夏琳燕;黄明辉;吴镇宇;杨义;屈子敬(School of Mechanical and Electrical Engineering,Central South University,Changsha 410083,China;Light Alloy Research Institute,Central South University,Changsha 410083,China;Guangxi Liuzhou Yinhai Aluminum Company Limited,Liuzhou 545006,China)

机构地区：[1]School of Mechanical and Electrical Engineering,Central South University,Changsha 410083,China [2]Light Alloy Research Institute,Central South University,Changsha 410083,China [3]Guangxi Liuzhou Yinhai Aluminum Company Limited,Liuzhou 545006,China

出　　处：《Journal of Central South University》2022年第3期836-847,共12页中南大学学报（英文版）

基　　金：Project(U21A20132) supported by the National Natural Science Foundation of China;Project(Gui Renzi2019(13))supported by the Guangxi Specially-invited Experts Foundation of Guangxi Zhuang Autonomous Region,China。

摘　　要：While pre-deformation is often conducted before aging treatment to increase the strength and microhardness of 2195 Al-Li alloy, it often increases the fatigue crack growth(FCG) rate and thus reduces the fatigue life of the alloy.To determine the effects and causes of pre-deformation and heat treatment on the mechanical properties and FCG rate of2195 Al-Li alloy, and to provide a suitable calculation model for the FCG rate under different pre-deformation conditions, 2195 Al-Li alloy specimens with different degrees of pre-rolling(0, 3%, 6%, and 9%) were investigated. The experimental results indicate that with the increase of pre-rolling, the density of the T1phase and the uniformity of the S′distribution and the microhardness, tensile strength, and yield strength of the alloy increase and at the same time the FCG rate increases, and thus the fatigue life is reduced. It was also found that the normalized stress intensity factor of elastic modulus(E) can be applied to correlate the FCG rate of pre-rolled 2195 Al-Li alloy with constant C and K parameters.时效前的预变形处理可增加2195铝锂合金的强度和硬度,但这会加快合金的疲劳裂纹扩展(FCG)速率,从而缩短合金的疲劳寿命。确定合适的预变形-时效工艺制度,在提高2195铝锂合金的强度和硬度的同时尽量降低其对疲劳裂纹扩展速率的影响,是进一步提高铝锂合金服役性能的关键。为此,研究了预变形程度(0、3%、6%和9%)对2195铝锂合金试样的硬度、强度、裂纹扩展速率以及疲劳断裂形貌与析出相等影响规律,揭示预变形对2195铝锂合金力学性能和FCG速率影响的作用机制。结果表明:随着预变形量的增加,T1相密度增加、S′相分布细化,导致合金显微硬度、抗拉强度和屈服强度增加,同时FCG速率加快、合金疲劳寿命缩短。同时,还提供了不同预变形程度下2195铝锂合金FCG速率的计算模型,将弹性模量(E)作为归一化应力强度因子,实现预变形后2195铝锂合金的FCG速率与常数C和K相关联,较好地预测了不同预变形状态下2195铝锂合金的裂纹扩展速率。

关 键 词：2195 Al-Li alloy pre-rolling OVER-AGING fatigue crack growth mechanical properties 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG156.9[金属学及工艺—金属材料]