优化红外热像法快速准确测定工业纯钛疲劳极限  

An Optimized Method for Thermographic Determination of Fatigue Limit in Commercially Pure Titanium

作　　者：曹东东 李璞 吴磊 纪红 史冰绡 马通达 Cao Dongdong;Li Pu;Wu Lei;Ji Hong;Shi Bingxiao;Ma Tongda(GRIMAT Engineering Institute Co.,Ltd.,Beijing,101407,China;National Analysis and Testing Center for Nonferrous Metals and Electronic Materials,China GRINM Group Co.,Ltd..,Bejing 100088,China;Guobiao(Beijing)Testing&Certification Co.,Ltd.,Beijing 101407,China;General Research Institute for Nonferrous Metals,Beijing100088,China)

机构地区：[1]有研工程技术研究院有限公司,北京101407 [2]中国有研科技集团有限公司国家有色金属及电子材料分析测试中心,北京100088 [3]国标(北京)检验认证有限公司,北京101407 [4]北京有色金属研究总院,北京100088

出　　处：《稀有金属》2024年第4期602-608,共7页Chinese Journal of Rare Metals

基　　金：国家重点研发计划项目(2017YFB0702100)资助。

摘　　要：采用红外热像法实时监测疲劳实验过程中工业纯钛TA1试样表面的温度变化,运用固有耗散理论对热像数据进行分析。提出以弹性极限作为热像数据分界限进行Luong法线性拟合的新方法,在唯一测定温升拐点的基础上快速准确预测了疲劳极限。力学拉伸实验测定试样弹性极限为313 MPa,以此为数据分界限进行线性拟合获得的疲劳极限结果为323 MPa,与传统升降法(309 MPa)相对偏差仅为4.5%。通过定位跟踪方法观察了疲劳循环应力加载过程中微观组织演化,发现经300 MPa及以下应力加载后,试样表面呈单一α相组织特征,晶粒形态、尺寸、分布未见明显变化;经350 MPa应力加载后,个别晶粒内可见少量滑移带,滑移带长直且相互平行。试样在循环加载应力达到疲劳极限时微观组织结构从可逆滞弹性形变转变为永久塑性形变,由此导致固有耗散由滞弹性机制转变为塑性机制,在试样表面温度变化上表现为温升拐点的出现。Fatigue limit is one of the most important properties of engineering materials.The long test time and the large number of specimens are required for the determination of the fatigue limit.The infrared thermography methods are developed to determine fatigue limit on basis of intrinsic dissipation.Two curves were utilized to interpolate experimental data by Luong,one for stresses below and the other for stresses above the fatigue limit,and the corresponding intersection was indicated as the fatigue limit.Whereas,it was not clearly specified how to recognize the experimental points below and above the fatigue limit in details,so that possibly failed in determining the reliable fatigue limit.Luong thermographic method was optimized to predict the fatigue limit.In order to illustrate the internal mechanism of the above optimized method,the relationship was investigated between intrinsic dissipation and microstructure evolution in this paper.Commercially pure titanium TA1 was investigated on fatigue limit,and the static tensile tests were performed to obtain stress-stain curve.In order to measure the fatigue limit by stair-case method,stress-controlled fatigue tests with a sinusoidal load were carried out on specimens.Thermography method based on stepwise loading procedure was used to rapidly obtain the fatigue limit.The temperature increment of the specimen surface was detected using an infrared camera during the fatigue test.Obviously,it was necessary to previously identify the border between the experimental data below and above the fatigue limit for Luong method.For conveniently practical applications,the elastic limit was proposed to divide the experimental data into two groups,one group for the elastic stress and the other for inelastic stress.To make clear the relationship between intrinsic dissipation and microstructure evolution from elastic strain to plastic strain,the microstructure of specimen subjected to different stresses loading was observed by the position-tracing method.Based on the above experiments,

关 键 词：钛合金 红外热像法 疲劳极限 快速测定方法 

分 类 号：TG146.23[一般工业技术—材料科学与工程]