TY - JOUR
T1 - Interpretation of cryogenic-temperature Charpy fracture initiation and propagation energies by microstructural evolution occurring during dynamic compressive test of austenitic Fe-(0.4,1.0)C-18Mn steels
AU - Kim, Hyunmin
AU - Park, Jaeyoung
AU - Jung, Joong Eun
AU - Sohn, Seok Su
AU - Lee, Sunghak
N1 - Funding Information:
This work was supported by the Ministry of Knowledge Economy under a Grant no. 10044574-2013-45 .
PY - 2015/7/4
Y1 - 2015/7/4
N2 - In the present study, Charpy impact energy (ET) composed of fracture initiation energy (EI) and propagation energy (EP) of austenitic Fe-(0.4,1.0)C-18Mn steels was evaluated in the temperature range from room to cryogenic temperatures by an instrumented Charpy impact tester, and was interpreted by microstructural evolution of dynamically compressed specimens. In the 1.0C-18Mn steel, the EI and EP decreased slightly with decreasing temperature, but the EP/ET ratio was kept to be about 0.5. In the 0.4C-18Mn steel, the EI remained almost constant or slightly decreased with decreasing temperature, while the EP/ET ratio steadily decreased, thereby leading to the lower (about 30%) cryogenic-temperature ET than that of the 1.0C-18Mn steel. Under the dynamic compressive loading, a considerable number of ε-martensites were formed in the 0.4C-18Mn steel, whereas they were not found in the 1.0C-18Mn steel, and their volume fractions increased steadily with decreasing temperature. This γ→ε-martensite transformation was attributed to the decrease in stacking fault energy, and resulted in the very low EP and resultant ET.
AB - In the present study, Charpy impact energy (ET) composed of fracture initiation energy (EI) and propagation energy (EP) of austenitic Fe-(0.4,1.0)C-18Mn steels was evaluated in the temperature range from room to cryogenic temperatures by an instrumented Charpy impact tester, and was interpreted by microstructural evolution of dynamically compressed specimens. In the 1.0C-18Mn steel, the EI and EP decreased slightly with decreasing temperature, but the EP/ET ratio was kept to be about 0.5. In the 0.4C-18Mn steel, the EI remained almost constant or slightly decreased with decreasing temperature, while the EP/ET ratio steadily decreased, thereby leading to the lower (about 30%) cryogenic-temperature ET than that of the 1.0C-18Mn steel. Under the dynamic compressive loading, a considerable number of ε-martensites were formed in the 0.4C-18Mn steel, whereas they were not found in the 1.0C-18Mn steel, and their volume fractions increased steadily with decreasing temperature. This γ→ε-martensite transformation was attributed to the decrease in stacking fault energy, and resulted in the very low EP and resultant ET.
KW - Cryogenic temperature
KW - Dynamic compressive test
KW - High-Mn steel
KW - Instrumented Charpy impact toughness
KW - Martensitic transformation
KW - Twin
UR - http://www.scopus.com/inward/record.url?scp=84947280399&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84947280399&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2015.05.095
DO - 10.1016/j.msea.2015.05.095
M3 - Article
AN - SCOPUS:84947280399
SN - 0921-5093
VL - 641
SP - 340
EP - 347
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
ER -