DENG Rongying
,
YE Zhijun Institute of Mechanics
,
Academia Sinica
,
Beijing
,
China LIU Shuhua
,
ZOU Dingqiang China Academy of Railway Sciences
,
Beijing
,
China Institute of Mechanics
,
Academia Sinica
,
Beijing 100080
,
China
金属学报(英文版)
The effect of ferrite content in ferrite-martensite dual-phase steel on the initiation and prop- agation of fatigue crack and the plastic deformation at crack tip has been studied.In the range of ferrite content from 24.2 to 41.5%,the optimum seems to be 33.8%,of which the crack ini- tiation will be prolonged,the threshold value increased,the propagation rate decreased and the closure stress intensity factor increased.As the propagation force is described by effective stress intensity factor,three steels with various ferrite contents will show the same propagation behaviour on da/dN vs △ K_(eff)curve.It is shown that the closure effect increases with the decrease in △K at the fatigue crack tip.When △K equals to △K_(th),the closure effect reaches a maximum value of0.7 in a dual-phase steel with 33.8%ferrite.
关键词:
dual-phase steel
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null
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