DENG Rongying ZHOU Aihua JIANG Huaiqing LI Chunxiu Institute of Mechanics
,
Academia Sinica
,
Beijing
,
ChinaZHANG Liqing
,
SUN Yutian Beijing Institute of Engineering
,
Beijing
,
China [Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A219—A225
,
Associate Profes sor
,
Institute of Mechanics
,
Academia Sinica
,
Beijing
,
China
金属学报(英文版)
The effect of pearlite interlamellar spacing(d)from 0.31 to 0.77 μm of T8 steel on fatigue crack propagation near threshold has been investigated at different stress ratios(R).The closure stress intensity factor(K_(cl)),the threshold value(ΔK_(th))and crack tip opening dis- placement range(ΔCOD)were measured.The results show that pearlite interlamellar spac- ing in this range has no effect on K_(cl),but has effect on the threshold value in low stress ratio. The threshold value is higher for materials with larger interlamellar spacing.No matter what the stress ratio is,during the propagation near threshold,the propagation rate will be the same,provieded the crack tip opening displacement range is the same. Metallurgical examinations were also carried out to show that the crack propagation path is sensitive to mierostructure.The crack always propagates along either boundary of pearlite colony or ferrite lamellar in pearlite.
关键词:
pearlitic steel
,
null
,
null
,
null
