王航
,
丁向东
,
肖林
金属学报
研究了相位角30o 、 60o 、90o和等效应变幅0.8%、0.6%、0.4%时双轴非比例加载下, 冷变形去应力状态Zr-4合金宏观响应和微观位错亚结构。结果表明: 应力矢量和应变增量矢量之间的滞迟角 在循环变形初期表现为较大的变化幅度，随着塑性变形的进行，变化幅度逐渐减小，并趋于稳定。滞迟角的变化幅度与加载路径曲率的变化有关。90°相位角时，变化幅度最小，30°时变化幅度最大。在椭圆和圆形加载路径下，随着应变路径弧长 的增大，等效应力的平均值升高，而变化幅度减小，并逐渐趋于稳定。随着相位角提高，等效应力响应的平均值升高。Zr-4合金在非比例加载过程中表现出初始硬化，随后持续软化的特征。随着相位角提高，循环软化程度加剧。非比例循环过程中Zr-4合金的等效应力高于相同等效应变幅下的比例加载, 表现出潜在强化特征。TEM观察表明：随着相位角的增加，Zr-4合金双轴疲劳位错亚结构由单个位错线向位错缠结及成熟的位错胞转化。材料内部各向同性强化机理加强是Zr-4合金非比例潜在强化的主要原因。
关键词:
Zr-4合金
,
proportional loading
,
non-proportional loading
,
additional hardening
,
dislocation
PEI Hongxun Institute of Corrosion and Protection of Metals
,
Academia Sinica
,
Shenyang
,
China Institute of Corrosion and Protection of Metals
,
Academia Sinica
,
Shenyang
,
China
金属学报(英文版)
Based on the experimental study of complex biaxial mode Ⅰ fatigue crack growth and the discussion on Von Mises'theory,a new approach is proposed for correlating crack propaga- tion rate under both in-phase and out-of-phase biaxial stress cycling.The results emphasize the contribution of plasticity to fatigue crack growth.
关键词:
biaxial stress
,
null
,
null
,
null
R.Bardenheier
,
G.Rogers
金属学报(英文版)
Two different types of experimental techniques to perform non-isothermal, uniaxial and biaxial fatigue tests were described. A new miniaturised electrothermalmechanical test rig was presented and discussed. It enables testing of small specimens under complex thermomechanical loading conditions. In order to cope with the simulation of well defined biaxial proportional and non-proportional loadings with in-phase and out-of-phase superposition of thermal loads a cruciform biaxial fatigue testing machine has been developed. Special design features of both machines, and the specimens tested, as well as typical test results were discussed.
关键词:
thermomechanical fatigue
,
null
,
null
