Bending Fatigue Property of Low-C Medium-Mn Steel with High Strength and Toughness

doi:10.12068/j.issn.1005-3026.2018.12.008

Abstract

Abstract: The three-point-bending fatigue property of low-C medium-Mn steel was studied by GPS-100 fatigue testing machine， where the S-N curve was plotted and the characteristics of fatigue fracture surface were analyzed. The effect of transformation induced plasiticity(TRIP)on fatigue property of the steel was also investigated. The results showed that the fatigue strength of the tested sample was about 1006MPa and the fatigue ratio was 1.20. The fatigue crack was originated from the corners in the lower surface of the sample. There were a large number of secondary cracks in the crack propagation zone， which could reduce the propagation rate effectively and improve fatigue strength of the steel. The fracture type was ductile for the axial dimples and elongated dimples were observed in the transient fracture zone. Furthermore， the excellent fatigue property of this steel was mainly attributed to the TRIP effect of retained austenite in the small plastic deformation zone in front of the fatigue crack， which could absorb a large amount of strain energy， blunt crack and reduce the crack propagation rate.

Key words: medium-Mn steel, three-point-bending fatigue, fatigue strength, fatigue ratio, S-N curve, TRIP effect

CLC Number:

TG115.5

QI Xiang-yu， DONG Ying， HU Jun， DU Lin-xiu. Bending Fatigue Property of Low-C Medium-Mn Steel with High Strength and Toughness[J]. Journal of Northeastern University Natural Science, 2018, 39(12): 1712-1716.

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