应变速率对TC17和TC4钛合金锻件力学性能的影响  

Effect of strain rate on mechanical properties of TC17 and TC4 alloy forgings

作　　者：陈钰浩 闵小华[1] 张海洋 戴进财 周轶群 CHEN Yuhao;MIN Xiaohua;ZHANG Haiyang;DAI Jincai;ZHOU Yiqun(School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China;Key Laboratory of Impact Dynamics on Aero Engine,AECC Shenyang Engine Design and Research Institute,Shenyang 110042,China;College of Civil Aviation,Northwestern Polytechnical University,Xi’an 710072,China)

机构地区：[1]大连理工大学材料科学与工程学院,辽宁大连116024 [2]中国航发沈阳发动机研究所辽宁省航空发动机冲击动力学重点实验室,沈阳110042 [3]西北工业大学民航学院,西安710072

出　　处：《航空材料学报》2023年第3期49-59,共11页Journal of Aeronautical Materials

基　　金：辽宁省航空发动机冲击动力学重点实验室开放基金项目(JC36021050017);国家自然科学基金项目(52071051)。

摘　　要：利用拉伸试验机研究不同应变速率对TC17和TC4钛合金锻件力学性能的影响,并利用Vickers硬度计、OM、SEM、EBSD等对两种钛合金的维氏硬度、变形组织以及断口形貌进行研究。结果表明:随着应变速率的增加,两种钛合金的强度升高而伸长率降低,均表现出正流变应力的应变速率敏感性,且应变速率敏感性系数随真应变增加呈现下降趋势;在相同应变速率下,除合金元素的固溶强化外,TC17钛合金网篮组织中板条状α相与残余β相交错排列,导致相界面多,位错容易在相界面塞积且位错运动的平均自由行程较短,合金的强度较高;另外,微孔易在相界面处大量形核,导致断口韧窝尺寸较小且数目较多,合金的塑性较差;TC4钛合金双态组织中等轴初生α相具有较好的协调变形能力,且β转变组织中的次生α相排列较为规则,导致相界面较少,降低了对位错运动的阻碍作用,韧窝尺寸较大且数目较少,合金的强度较低而塑性较好。α+βtitanium alloys have a wide application prospect in aero engine blisk manufacturing,owing to their high specific strength and good high-temperature performance.Whereas there are few studies on mechanical properties and plastic deformation modes of large-size blisk specimens at variable strain rate conditions.In this work,the effects of different strain rates on the mechanical properties of forged TC17 and TC4 alloys were examined by tensile testing machine,and Vickers hardness tester,OM,SEM,and EBSD were used to study the Vickers hardness,deformation microstructures and fracture morphologies.As increasing strain rate,the strengths of both alloys increase and the elongation decrease,showing positive strain rate sensitivities of flow stress,and the strain rate sensitivity coefficients decrease with true strain.Besides the solid solution strengthening of alloying elements,lathα-phases and residualβ-phases in TC17 alloy with basket-weave microstructure are interweaved with each other,resulting in more phase interfaces.Phase interfaces are effective in blocking dislocations motion and lead to pile-up of dislocations,improving the strength of TC17 alloy.In addition,the voids are easier to nucleate at the phase interfaces and form dimples.Therefore,a lot of small dimples are observed on the fracture surface,which make the poorer ductility of TC17 alloy.Fewer phase interfaces exist in TC4 alloy with bimodal microstructure,which is related to the better plastic deformation capacity of equiaxed primaryα-phases and the regular arrangement of secondaryα-phases in transformedβ-phases.The fewer phase interfaces increase the mean free path of dislocations and form fewer large dimples,which lead to a decrease in strength but an increase in ductility of TC4 alloy.

关 键 词：整体叶盘 α+β型钛合金 应变速率 变形组织 断口形貌 

分 类 号：TG146.2[一般工业技术—材料科学与工程]