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Abstract
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Article Information:
Fatigue Crack Initiation Analysis in 1060 Steel
L. Gyansah and A.K. Ansah
Corresponding Author: L. Gyansah
Submitted: 2010 March, 12
Accepted: 2010 May, 08
Published: 2010 July, 10 |
Abstract:
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This study investigates initiation of small cracks on dumble-shaped plate type specimens of 1060
steel at the load ratio of R = 0 under varied cyclic stress amplitudes between 0.6 and 1.0 of yield stress using
the Instron machine (model: 8501). Sinusoidal wave of a frequency of 10 Hz was used in the experiment. The
experiment was conducted at a room temperature of 23ºC. Each test for different applied stress ranges was
carried out for 2×104 cycles. Microstructure and fractography of the fractured specimen were also analyzed.
Nucleations of cracks were observed at Ferrite-Ferrite G rain Boundary (FFGB) as well as inside Ferrite Grain
Body (FGB), but the FFGB location was preferred. Results show that the average length of FFGB cracks is
found larger than that of the average length of cracks initiated inside FGB at the same cyclic loading conditions.
The formation of slip band inside grain body, slip band impingement at grain boundary and elastic-plastic
incompatibility synergistically have significant influence on fatigue crack initiation in 1060 steel. Additionally,
the formation of irregular voids inside slip bands, initiation and growth of small voids at grain boundary and
the subsequent joining of these with other voids were seen as specific characteristics of 1060 steel. It was also
established that cracks nucleate both at grain boundary and inside grain body in 1060 steel in the investigated
domain of 0.6 to 1.0Fy.It was further established that the orientation of the grain body cracks at low stress level
is greater than 45º and the average angle of orientation of these cracks increases like that of grain boundary
cracks with increased magnitude of stress range.
Key words: Crack initiation, cyclic loading, fatigue, ferrite grain body, ferrite grain boundary, fractography, growth, small crack, 1060 steel
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Abstract
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Cite this Reference:
L. Gyansah and A.K. Ansah, . Fatigue Crack Initiation Analysis in 1060 Steel. Research Journal of Applied Sciences, Engineering and Technology, (4): Page No: 319-325.
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ISSN (Online): 2040-7467
ISSN (Print): 2040-7459 |
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