TY - GEN
T1 - Evaluation of creep deformation mechanism of heat resistant steel by stress change test
AU - Hayakawa, Hiroyuki
AU - Nakashima, Satoshi
AU - Kusumoto, Junichi
AU - Terada, Daisuke
AU - Yoshida, Fuyuki
AU - Nakashima, Hideharu
PY - 2008
Y1 - 2008
N2 - In order to evaluate creep deformation mechanism of heat resistant steels, stress change tests were conducted during creep tests. In this study, it was confirmed that the dislocation behavior during the creep tests was in viscous manner, because no instantaneous plastic strain was observed at stress increments. Transient behavior was observed after stress changes for all kinds of steel in this work. Mobility of dislocation was evaluated by the observed backward creep behavior after stress reduction. Internal stress was evaluated by the change of creep rate in stress increment, and mobile dislocation density was evaluated with the estimated mobility of dislocation and the change of creep rate in stress increment. It was found that the variation of mobile dislocation density during creep deformation showed the same tendency as the variation of creep rate. Therefore mobile dislocation density is the dominant factor that influences the creep rate variation in creep deformation of heat resistant steels investigated in this work. The mobility of dislocation showed a good correlation with 1/T and it is related with the amount of solute Mo that is a solution strengthening element. Microstructure of crept specimens was observed by TEM to discuss the validation of these results.
AB - In order to evaluate creep deformation mechanism of heat resistant steels, stress change tests were conducted during creep tests. In this study, it was confirmed that the dislocation behavior during the creep tests was in viscous manner, because no instantaneous plastic strain was observed at stress increments. Transient behavior was observed after stress changes for all kinds of steel in this work. Mobility of dislocation was evaluated by the observed backward creep behavior after stress reduction. Internal stress was evaluated by the change of creep rate in stress increment, and mobile dislocation density was evaluated with the estimated mobility of dislocation and the change of creep rate in stress increment. It was found that the variation of mobile dislocation density during creep deformation showed the same tendency as the variation of creep rate. Therefore mobile dislocation density is the dominant factor that influences the creep rate variation in creep deformation of heat resistant steels investigated in this work. The mobility of dislocation showed a good correlation with 1/T and it is related with the amount of solute Mo that is a solution strengthening element. Microstructure of crept specimens was observed by TEM to discuss the validation of these results.
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U2 - 10.1115/CREEP2007-26501
DO - 10.1115/CREEP2007-26501
M3 - Conference contribution
AN - SCOPUS:43449100665
SN - 0791842878
SN - 9780791842874
T3 - 2007 Proceedings of the ASME Pressure Vessels and Piping Conference - 8th International Conference on Creep and Fatigue at Elevated Temperatures - CREEP8
SP - 533
EP - 542
BT - 2007 Proceedings of the ASME Pressure Vessels and Piping Conference - 8th International Conference on Creep and Fatigue at Elevated Temperatures - CREEP8
T2 - 2007 ASME Pressure Vessels and Piping Conference - 8th International Conference on Creep and Fatigue at Elevated Temperatures, PVP-2007/CREEP8
Y2 - 22 July 2007 through 26 July 2007
ER -