The hot deformation and dynamic recrystallization （DRX） behavior of austenite-based Fe-27Mn-ll.5A1- 0.95C steel with a density of 6.55 g cm-3 were investigated by compressive deformation at the temperature range of ...The hot deformation and dynamic recrystallization （DRX） behavior of austenite-based Fe-27Mn-ll.5A1- 0.95C steel with a density of 6.55 g cm-3 were investigated by compressive deformation at the temperature range of 900-1150 ℃ and strain rate of 0.01-10 s-1. Typical DRX behavior was observed under chosen deformation conditions and yield-point-elongation-like effect caused by DRX of 6-ferrite. The flow stress characteristics were determined by DRX of the 6-ferrite at early stage and the austenite at later stage, respectively. On the basis of hyperbolic sine function and linear fitting, the calculated thermal activation energy for the experimental steel was 294.204 kJ mo1-1. The occurrence of DRX for both the austenite and the 6-ferrite was estimated and plotted by related Zener-Hollomon equations. A DRX kinetic model of the steel was established by flow stress and peak strain without considering dynamic recovery and 6-ferrite DRX. The effects of deformation temperature and strain rate on DRX volume fraction were discussed in detail. Increasing deformation temperature or strain rate contributes to DRX of both the austenite and the 6-ferrite, whereas a lower strain rate leads to the austenite grains growth and the 6-ferrite evolution, from banded to island-like structure.展开更多
Fully reversed tensile-compression low-cycle fatigue tests were performed at room temperature under strain amplitude of 0.4%.The monotonic tensile results show that Fe-26Mn-10A1-C steels are fully austenite and(he opt...Fully reversed tensile-compression low-cycle fatigue tests were performed at room temperature under strain amplitude of 0.4%.The monotonic tensile results show that Fe-26Mn-10A1-C steels are fully austenite and(he optimal combination of ultimate tensile strength and total elongation was present at 950°C with 65 GPa%.The fatigue results show that the specimen at 1050°C has the maximum fatigue life of 162,000 cycles,which is much longer than twinning-induced plasticity(TWIP)steels of the same strain amplitude.The hot-forging specimen shows high similarity with TWIP steels with rapid initial cyclic hardening followed by cyclic softening and cyclic saturation.After solution heat treatment,it is noteworthy that,after rapid initial cyclic softening,another rapid cyclic hardening and a following decrease with fluctuation were observed at 1000°C.It is reas on able to believe that it is caused by K-carbides precipitated during cyclic deformation.Anolher interesting phenomenon is cyclic stress subsidence observed at 1050°C during its saturation stage at the last quarter of the fatigue life,and the span is about 12.5%of whole fatigue life.展开更多
文摘The hot deformation and dynamic recrystallization （DRX） behavior of austenite-based Fe-27Mn-ll.5A1- 0.95C steel with a density of 6.55 g cm-3 were investigated by compressive deformation at the temperature range of 900-1150 ℃ and strain rate of 0.01-10 s-1. Typical DRX behavior was observed under chosen deformation conditions and yield-point-elongation-like effect caused by DRX of 6-ferrite. The flow stress characteristics were determined by DRX of the 6-ferrite at early stage and the austenite at later stage, respectively. On the basis of hyperbolic sine function and linear fitting, the calculated thermal activation energy for the experimental steel was 294.204 kJ mo1-1. The occurrence of DRX for both the austenite and the 6-ferrite was estimated and plotted by related Zener-Hollomon equations. A DRX kinetic model of the steel was established by flow stress and peak strain without considering dynamic recovery and 6-ferrite DRX. The effects of deformation temperature and strain rate on DRX volume fraction were discussed in detail. Increasing deformation temperature or strain rate contributes to DRX of both the austenite and the 6-ferrite, whereas a lower strain rate leads to the austenite grains growth and the 6-ferrite evolution, from banded to island-like structure.
文摘Fully reversed tensile-compression low-cycle fatigue tests were performed at room temperature under strain amplitude of 0.4%.The monotonic tensile results show that Fe-26Mn-10A1-C steels are fully austenite and(he optimal combination of ultimate tensile strength and total elongation was present at 950°C with 65 GPa%.The fatigue results show that the specimen at 1050°C has the maximum fatigue life of 162,000 cycles,which is much longer than twinning-induced plasticity(TWIP)steels of the same strain amplitude.The hot-forging specimen shows high similarity with TWIP steels with rapid initial cyclic hardening followed by cyclic softening and cyclic saturation.After solution heat treatment,it is noteworthy that,after rapid initial cyclic softening,another rapid cyclic hardening and a following decrease with fluctuation were observed at 1000°C.It is reas on able to believe that it is caused by K-carbides precipitated during cyclic deformation.Anolher interesting phenomenon is cyclic stress subsidence observed at 1050°C during its saturation stage at the last quarter of the fatigue life,and the span is about 12.5%of whole fatigue life.
