冷变形TB3合金二次时效后低周疲劳行为的研究  

Low Cycle Fatigue Behavior of Secondary Aging Treated TB3 Alloy Cold Preformed

作　　者：宋振亚[1,2] 张临财[3] 郭啸栋[3] 孙巧艳[2] 肖林[2] 孙军[2] 

机构地区：[1]绍兴文理学院,浙江绍兴312000 [2]西安交通大学金属材料强度国家重点实验室,陕西西安710049 [3]淮阴工学院,江苏淮安223003

出　　处：《稀有金属材料与工程》2014年第2期435-439,共5页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(51101068)

摘　　要：对于经过冷变形的固溶态Ti-10Mo-8V-1Fe-3.5Al(TB3)合金,透射电子显微镜(TEM)观察结果表明:其内部冷变形产生的高密度位错在常规时效后依然大量存在,这将导致合金材料力学性能的劣化。针对此问题,本实验研究了一种二次时效工艺,在常规时效基础上增加了短时间高温时效阶段。TEM观察结果表明,二次时效工艺处理后,合金内部位错密度大幅降低,与此同时时效析出的α片出现了变体选择效应。对经过冷变形及二次时效工艺处理后的TB3合金试样(SA试样)和未变形的常规峰值时效状态试样(FA试样)进行低周轴向拉压疲劳测试结果表明:在总应变幅低于0.01时,SA试样疲劳寿命稍高;总应变幅高于0.01时,FA试样疲劳寿命稍高。另外,对低周疲劳测试后的试样TEM观察结果表明:(1)位错滑移是该合金低周疲劳过程中的主要变形方式;(2)低周疲劳产生的位错条带结构在FA试样中较宽且不连续,而在SA试样中细小均匀。For the cold pre-deformed Ti-10Mo-8V-1Fe-3.5Al （TB3） alloy, the high density of dislocation could still be observed after traditional aging treatment, which could lead to detrimental influences on mechanical properties. To resolve this problem, a second aging treatment process was proposed. Transmitting electron microscopy （TEM） investigations show that the dislocation density may be dramatically decreased by the secondary aging treatment in predeformed TB3 samples. Variant selection effect was observed in predeformed and aged TB3 samples. Low cycle fatigue （LCF） tests were carried out to the conventional peak aged TB3 samples （FA） and the predeformed and secondary aging treated TB3 samples（SA）. The LCF results show that fatigue lifetime is slightly higher for SA samples when the total strain amplitude is lower than 1%, but it has an opposite result when the total strain amplitude is higher than 1%. TEM investigations on the TB3 samples after fatigue tests show that dislocation slip is the predominant deformation mode. The dislocation bands resulting form cyclic deformation are wide and discontinuous in FA sample, however they are fine and homogeneous in SA samples.

关 键 词：Β钛合金 预变形 二次时效 低周疲劳行为 变体选择效应 

分 类 号：TG146.23[一般工业技术—材料科学与工程]