铸造TiAl合金疲劳寿命统计分布  

Statistical Distribution of Fatigue Life for Cast TiAl Alloy

作　　者：万文娟[1] 韩波[2] 韩伟[2] 张继[1] 

机构地区：[1]钢铁研究总院高温合金新材料北京市重点实验室,北京100081 [2]钢铁研究总院,北京100081

出　　处：《航空材料学报》2016年第4期71-77,共7页Journal of Aeronautical Materials

摘　　要：对铸造Ti-47.5Al-2.5V-1.0Cr-0.2Zr（原子分数/%）合金层片组织进行了疲劳测试,获得了单一应力下的疲劳寿命数据,通过断口观察和数据统计处理,分析了疲劳寿命的分布特点及其控制因素。结果表明：实验合金的疲劳寿命具有显著波动,波动范围为10^3~10^6周;并集中分布在长、短两个寿命区间内。这一现象和导致疲劳试样失效的疲劳裂纹源的类型有关;其中,短寿命试样的疲劳裂纹起源于疏松孔洞,长寿命试样的疲劳裂纹源为弥合界面和软取向层片界面。建立了三种裂纹源对疲劳寿命的影响的两参数威布尔分布模型,可进行对应于某一失效概率的疲劳寿命预测。三种疲劳裂纹源中,疏松孔洞对疲劳寿命不利影响的程度最为严重。Statistic distribution of fatigue life data and its controls of cast Ti-47. 5Al-2. 5V-1. 0Cr-0. 2Zr（ atom fraction / %） alloy were investigated. Fatigue tests were operated by means of load-controlled rotating bending fatigue tests（ R =- 1） performed at a frequency of 100 Hz at 750 ℃ in air. The fracture mechanism was analyzed by observing the fracture surface morphologies through scanning electron microscope,and the achieved fatigue life data were analyzed by Weibull statistics. The results show that the fatigue life data present a remarkable scatter ranging from 10^3 to 10^6 cycles,and distribute mainly in short and long life regime. The reason for this phenomenon is that the fatigue crack initiators are different with different specimens. The crack initiators for short-life specimens are caused by shrinkage porosity,and for long-life ones are caused by bridged porosity interface and soft-oriented lamellar interface. Based on the observation results of fracture surface,two-parameter Weibull distribution model for fatigue life data can be used for the prediction of fatigue life at a certain failure probability. It has also shown that the shrinkage porosity causes the most detrimental effect to fatigue life.

关 键 词：TIAL合金 疲劳寿命 铸造缺陷 威布尔分布 

分 类 号：TG146.2[一般工业技术—材料科学与工程]