TY - JOUR
T1 - Effect of retained austenite stability on cyclic deformation behavior of low-alloy transformation-induced plasticity steels
AU - Christodoulou, Peter I.
AU - Kermanidis, Alexis T.
AU - Chaidemenopoulos, Grigorios
AU - Krizan, Daniel
AU - Polychronopoulou, Kyriaki
N1 - Funding Information:
This work was financially supported partially by the project “Smart Pole for Specialization and Development of Thessaly: Research, Innovation, Strategies,” implemented in the framework of the “KRIPIS” Program of the General Secretariat for Research and Technology (GSRT), National Strategic Reference Framework (NSRF), and partially by the IKYDA program “Cyclic deformation of TRIP steels” between RWTH Aachen and University of Thessaly. The authors are grateful to the Steel Institute, Department of Ferrous Metallurgy (IEHK) of RWTH Aachen University, for the heat treatment of materials.
Publisher Copyright:
© 2019 Wiley Publishing Ltd.
PY - 2019/5
Y1 - 2019/5
N2 - The retained austenite (RA) characteristics of Al-containing TRIP700 steels have been manipulated using varying bainitic isothermal transformation (BIT) processing. The microstructural evolution was investigated using optical microscopy and quantitative image analysis, while the amount of transformed RA was evaluated with the saturation magnetization (SM) technique. Cyclic behavior is found to depend on the applied strain amplitude and stability of RA. At strain amplitudes with comparable elastic and plastic strain components, cyclic softening prevails, facilitated by more stable RA microstructures and Low Cycle Fatigue (LCF) performance benefits from a lower RA stability, which controls the amount of cyclic softening rate. With increasing plastic strain component, a transition to cyclic hardening is observed, and the transition strain increases with increasing RA stability. LCF performance deteriorates because of excessive cyclic strain hardening promoting martensitic transformation. The effect is accompanied by a transition from mixed dimple/cleavage to cleavage-type fracture characteristics.
AB - The retained austenite (RA) characteristics of Al-containing TRIP700 steels have been manipulated using varying bainitic isothermal transformation (BIT) processing. The microstructural evolution was investigated using optical microscopy and quantitative image analysis, while the amount of transformed RA was evaluated with the saturation magnetization (SM) technique. Cyclic behavior is found to depend on the applied strain amplitude and stability of RA. At strain amplitudes with comparable elastic and plastic strain components, cyclic softening prevails, facilitated by more stable RA microstructures and Low Cycle Fatigue (LCF) performance benefits from a lower RA stability, which controls the amount of cyclic softening rate. With increasing plastic strain component, a transition to cyclic hardening is observed, and the transition strain increases with increasing RA stability. LCF performance deteriorates because of excessive cyclic strain hardening promoting martensitic transformation. The effect is accompanied by a transition from mixed dimple/cleavage to cleavage-type fracture characteristics.
KW - bainitic isothermal transformation
KW - cyclic behavior
KW - formability
KW - retained austenite stability
KW - retained austenite transformation
KW - transformation-induced plasticity steel
UR - https://www.scopus.com/pages/publications/85059677883
U2 - 10.1111/ffe.12972
DO - 10.1111/ffe.12972
M3 - Article
AN - SCOPUS:85059677883
SN - 8756-758X
VL - 42
SP - 1085
EP - 1099
JO - Fatigue and Fracture of Engineering Materials and Structures
JF - Fatigue and Fracture of Engineering Materials and Structures
IS - 5
ER -