CAJ | 학술논문

通过一系列单轴应力循环实验对T225NG钛合金进行了长次循环棘轮行为研究.研究表明,在一定峰值应力范围内经数万次应力循环后材料具有棘轮安定性;棘轮疲劳损伤与幅值应力和峰值应力相关,当幅值应力为峰值应力的一半时,棘轮变形达到安定后产生疲劳破坏,疲劳寿命与峰值应力或SR应变(饱和棘轮应变)之间满足幂律关系;在幅值应力仅为峰值应力的1%～2.5%时,材料依然可以产生棘轮塑性应变累积并经过数十万次循环后达到安定,且蠕变附加效应不显著;当峰值应力取为屈服强度85％～100％时,初始棘轮塑性应变率为零,但经过数万次循环后仍可以产生1.4％～2.5％塑性应变累积.基于峰值应力与T225NG合金单轴棘轮塑性累积之间所具有的单调特性以及棘轮演化的门槛特性,本文重点发展了SRM抛物律本构模型,该模型可较好预测T225NG合金单轴SR应变,也可用于估算蠕变的安定塑性累积.论文还讨论了关于棘轮演化的分类问题.
통과일계렬단축응력순배실험대T225NG태합금진행료장차순배극륜행위연구.연구표명,재일정봉치응력범위내경수만차응력순배후재료구유극륜안정성;극륜피로손상여폭치응력화봉치응력상관,당폭치응력위봉치응력적일반시,극륜변형체도안정후산생피로파배,피로수명여봉치응력혹SR응변(포화극륜응변)지간만족멱률관계;재폭치응력부위봉치응력적1%～2.5%시,재료의연가이산생극륜소성응변루적병경과수십만차순배후체도안정,차연변부가효응불현저;당봉치응력취위굴복강도85％～100％시,초시극륜소성응변솔위령,단경과수만차순배후잉가이산생1.4％～2.5％소성응변루적.기우봉치응력여T225NG합금단축극륜소성루적지간소구유적단조특성이급극륜연화적문함특성,본문중점발전료SRM포물률본구모형,해모형가교호예측T225NG합금단축SR응변,야가용우고산연변적안정소성루적.논문환토론료관우극륜연화적분류문제.
In order to investigate the ratcheting behavior of T225NG alloy, a series of ratcheting tests under uniaxial long-cyclic stressing were performed. The results show that the ratcheting strain of this alloy can get into shakedown after tens (or hundreds) of thousand cycles. After the ratcheting strain is saturated under the condition that stress amplitude is half of peak stress, it will bring about subsequent fatigue failure, and relationship between fatigue life and one of peak stress and saturated ratcheting (SR) strain meets power law. As the alloy is under stress jiggling with stress amplitude that is 1%-2.5% of peak stress, the ratcheting strain still become remarkable and goes into shakedown after several hundreds of thousand cycles but there exists little accessional strain caused by creep effect. It is notable that, when the peak stress is 85%-100% of yield stress, the long-cyclic stressing will lead SR strain to be from 1.4% to 2.5% even if the initial ratio of ratcheting strain is zero. Based on ratcheting threshold property of peak stress and monotonicity of relationship between the peak stress and SR strain, a saturated ratcheting model (SRM) is developed to predict SR strain and to estimate saturated creep strain also. In addition, the classes of ratcheting evolutions of metals are discussed.