陈铮
,
李明利
,
何明
金属学报
研究了7075,2090和2090+Ce合金的疲劳裂纹扩展行为。2090合金的名义疲劳裂纹扩展抗力优于7075合金,归因于其高的裂纹闭合效应,但其本征疲劳裂纹扩展抗力低于7075合金。在2090合金中添加微量Ce,可同时提高其本征疲劳裂纹扩展抗力和裂纹闭合效应,故其名义疲劳裂纹扩展抗力大幅度提高。
关键词:
Al-Li合金
,
Ce
,
fatigue crack
,
closure effect
,
intrinsic growth resistance
浩宏奇
,
宋余九
金属学报
本文研究了低碳Cr-Ni钢和低碳Si-Mn钢在3.5％NaCl盐雾介质中的疲劳裂纹扩展行为。试验结果表明:盐雾介质显著降低了疲劳裂纹萌生期,在试验的两种频率下,裂纹扩展dα/dN-ΔK曲线上出现了与ΔK无关的平台,且存在一临界应力强度因子幅ΔK值,高于此值,裂纹起裂且能连续扩展;低于此值,裂纹扩展易发生止裂现象。
关键词:
盐雾
,
initiation period
,
crack growth stoppage
,
closure effect
邓蓉英
,
叶智军
,
刘淑华
,
邹定强
金属学报
本文研究铁素体-马氏体复相钢中铁素体含量对裂纹萌生、扩展和裂纹尖端塑性变形的影响。在24.2—41.5％的铁素体含量范围内,以33.8％含量的复相钢裂纹萌生期N_0较长、门槛值ΔK_(th)高、并有低的扩展速率和较高的闭合应力强度因子K_(Cl)。 三种铁素体含量复相钢的dα/dN-ΔK_(eff)一致的事实,表明裂纹闭合对低速扩展的重要作用,且闭合程度(K_(Cl)/K_(max))随裂纹尖端ΔK的降低而提高,在ΔK_(th)时达到最大。铁素体含量为33.8％的K_(Cl)/K_(max)值最高达0.7。
关键词:
复相钢
,
fatigue crack
,
closure effect
WANG Zhongguang ZHANG Yun HU Zhuangqi State Key Laboratory for Fatigue and Fracture of Materials
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
ChinaHE Shiyu LI Qingjian Harbin Institute of Technology
,
Harbin
,
China
金属学报(英文版)
Fatigue crack growth rates of Al-Li alloy 8090 in air were found to be strongly dependent up- on the aging conditions.The naturally aged and underaged specimens showed the highest re- sistance to the fatigue crack propagation.The fatigue crack growth resistance of the overaged specimen is the lowest and that of the peakaged specimen in between.As compared to air, 3.5% NaCl solution does not change the effect of aging conditions on the fatigue crack growth,but causes a decrease of the resistance to the fatigue crack growth under the same ag- ing condition.Both short cracks from notch and physically short cracks showed much higher rates of fatigue crack propagation in comparison with long cracks under the same aging condi- tion and stress intensity level.The growth behavior of the short crack depends on its type.The growth rate of short crack from notch decreases first to a minimum and then increases with in- creasing △K.However,the physically short crack grows at a progressively increasing rate. The effects of aging conditions are explained in terms of the slip planarity of dislocations and the cyclic slip reversibility.The observed short crack behavior is considered to be dependent on the crack closure and the local plasticity near the crack tip.
关键词:
Al-Li alloy
,
null
,
null
,
null
HAO Hongqi SONG Yujiu Xi'an Jiaotong University
,
Xi'an
,
China Institute of Metallic Materials and Strength
,
Xi'an Jiaotong University
,
Xi'an
,
China
金属学报(英文版)
The corrosion fatigue propagation behaviour of high strength low alloy Cr-Ni and Si-Mn steels has been investigated in 3.5 %NaCl solution spryly at the frequencies of 0.1 and 5.5 Hz. It was shown that the fatigue crack initiation resistances of the two steels are significantly re- duced in salt spray;the fatigue crack growth rates of steels increase with the decrease of fre- quency and are much higher in salt spray than in air within low ΔK range.A critical stress in- tensity factor was observed for each steel and the crack growth stoppage will occur if the ΔK values are lower than it.It was found that the active dissolution makes great contribution to the fatigue crack growth within low ΔK range.
关键词:
salt spray
,
null
,
null
,
null
