Abstract:
An investigation
has been made on the relationship between microstructure and
fatigue property of an ultra-high strength low-carbon
martensitic steel. Results of the experiment show that the
experimental steel has an excellent fatigue strength and high
resistance to fatigue crack propagation when tempered at low
temperature. The dominant microstructural feature that
contributes to delay the nucleation of fatigue crack is fine and
dispersed carbides in dislocated martensite, whereas the
orientation difference between adjacent martensite packets,
martensite laths and retained austenite in the form of thin
interlath film are factors that control the rate of fatigue
crack propagation. Factors affecting deterioration of fatigue
behavior in tempered martensite embrittlement have also been
analysed and discussed.
Key words:
Ultra-high strength steel Fatigue
property Martensitic steel
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