日本金属学会誌

J. Japan Inst. Metals, Vol. 54, No. 12 (1990),
pp. 1350-1357

Low Cycle Fatigue-Hardening of TRIP-Aided Dual-Phase Steels

Shin-ichi Yasuki1, Koh-ichi Sugimoto2, Mitsuyuki Kobayashi3 and Shun-ichi Hashimoto4

1Graduate Student, Shinshu University, Ueda
2Department of Functional Machinery and Mechanics, Faculty of Textile Science and Technology, Shinshu University, Ueda
3Department of Mechanical Systems Engineering, Faculty of Engineering, Shinshu University, Nagano
4Iron and Steel Laboratories, Kobe Steel Ltd., Kobe

Abstract:

Low cycle fatigue behavior of 0.1~0.4%C-1.5%Si-1.5%Mn(in mass%) TRIP-aided dual-phase steels containing retained austenite of 6 to 20 vol% has been measured at room temperature and a role of retained austenite on this behavior has been investigated in terms of the measured Bauschinger stress.
Low cycle fatigue of TRIP-aided dual-phase steel was generally characterized by severe initial fatigue-hardening and successive small fatigue-hardening or fatigue-softening. The amount of initial fatigue-hardening increased with increasing initial retained austenite content and total strain amplitude. The fatigue properties were superior to those of the conventional ferrite-martensite dual-phase steel.
The fatigue-hardening was principally ascribed to the increased internal stress arising from a misfit strain between soft and hard phases. Retained austenite enhanced the internal stress due to the increase in fresh martensite content produced by the strain-induced transformation.


(Received 1990/7/2)

Keywords:

retained austenite, dual-phase steel, transformation induced plasticity, low cycle fatigue, fatigue-hardening, Bauschinger effect, Bauschinger stress, internal stress


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