Isothermal compression tests were carried out to investigate the hot deformation behavior of a multi-alloyed high-Mn austenitic steel,110Mn12Cr2NY,at temperatures ranging from 800 to 1200℃ and strain rates ranging fr...Isothermal compression tests were carried out to investigate the hot deformation behavior of a multi-alloyed high-Mn austenitic steel,110Mn12Cr2NY,at temperatures ranging from 800 to 1200℃ and strain rates ranging from 0.01 to 1 s^(−1).The results revealed that the critical strain for dynamic recrystallization(DRX)lowered with increasing deformation temperature and decreasing strain rate.The analysis of microstructure pointed to discontinuous dynamic recrystallization(DDRX)as the dominant DRX mechanism,characterized byΣ3 twin boundaries and necklace-like structure during deformation at relatively low temperature and high strain rate.The decrease in strain rate facilitated continuous dynamic recrystallization(CDRX)as an auxiliary nucleation mechanism,leading to a significant decrease in the softening rate in the flow stress curves.When deformed at high temperatures and low strain rates,the preferential growth of<001>oriented grains resulted in the formation of a strong<001>//CD texture,and CDRX associated with<001>grains emerged as the predominant DRX mechanism.Significant DRX occurring at high temperatures and high strain rates yielded fine,defect-free equiaxed grains.Consequently,this region could be employed as the optimal hot working window for 110Mn12Cr2NY steel,with a temperature range of 950–1200℃and a strain rate range of 0.4^(–)1 s^(−1).展开更多
Austenitic high-Mn steels with Mn contents between approximately 15 and 30 wt% gain much interest because of their excellent mechanical properties and the option for adjusting strain hardening behavior due to differen...Austenitic high-Mn steels with Mn contents between approximately 15 and 30 wt% gain much interest because of their excellent mechanical properties and the option for adjusting strain hardening behavior due to different deformation mechanisms. 2D and 3D composition-dependent stacking fault energy （SFE） maps indicate the effect of chemical composition and temperature on SFE and consequently on the deformation mechanisms. Three steels with different chemical compositions and the same or different SFE are characterized in quasi-static tensile tests. The control parameters of strain hardening behavior in the high-Mn austenitic steels are described, and consequences for future developments are discussed.展开更多
The formability of austenitic high-Mn steels is a critical issue in automotive applications under nonuniformly-deformed environments caused by dynamic strain aging.Among austenite stabilizing alloying elements in thos...The formability of austenitic high-Mn steels is a critical issue in automotive applications under nonuniformly-deformed environments caused by dynamic strain aging.Among austenite stabilizing alloying elements in those steels,Cu has been known as an effective element to enhance tensile properties via controlling the stacking fault energy and stability of austenite.The effects of Cu addition on formability,however,have not been sufficiently reported yet.In this study,the Cu addition effects on formability and surface characteristics in the austenitic high-Mn TRIP steels were analyzed in consideration of inhomogeneous microstructures containing the segregation of Mn and Cu.To reveal determining factors,various mechanical parameters such as total elongation,post elongation,strain hardening rate,normal anisotropy,and planar anisotropy were correlated to the hole-expansion and cup-drawing test results.With respect to microstructural parameters,roles of(Mn,Cu)-segregation bands and resultant Cu-rich FCC precipitates on the formability and surface delamination were also discussed.展开更多
Deformation-induced microstructures of high-Mn austenite steel was investigated by metallography,X-ray diffraction and SEM.The ε-martensite and slip-bands are deformation-in- duced on the{111} planes,and appear as th...Deformation-induced microstructures of high-Mn austenite steel was investigated by metallography,X-ray diffraction and SEM.The ε-martensite and slip-bands are deformation-in- duced on the{111} planes,and appear as thin straight laths with 60～80° alignment difference be- tween them.It was found that ε-martensite and slip bands are kinked at fcc twin boundaries with the kinked angle 35～40°.The bands of equilateral triangle in the microstructure of tensile deformation are presented.展开更多
To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were performed.The effects of Mn an...To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were performed.The effects of Mn and Al contents in the steel and the reaction time on the interfacial reaction were investigated.It was observed that the erosion of the MgO refractory is caused by the reaction of Al and Mn in the steel with MgO in the refractory,which would lead to the formation of(Mn,Mg)O·Al_(2)O_(3) spinel and(Mn,Mg)O solid solution.The formation mechanism of the spinel and solid solution is as follows.The Al in the steel firstly reacts with MgO in the refractory to generate MgO·Al_(2)O_(3) spinel,and then,the spinel reacts with Mn in the steel to form(Mn,Mg)O·Al_(2)O_(3) spinel.Finally,the MnO in the spinel reacts with the MgO in the inner refractory to form(Mn,Mg)O solid solution.In addition,only(Mn,Mg)O·Al_(2)O_(3) spinel is present in the interfacial reaction layer of the refractory when the Al content in the steel is sufficient.展开更多
基金the National Natural Science Foundation of China(Nos.52474427,52201143,and 52171049)the Science and Technology Project of Hebei Education Department(No.BJK2023033)the Hebei Province Innovation Ability Promotion Project(No.22567609H).
文摘Isothermal compression tests were carried out to investigate the hot deformation behavior of a multi-alloyed high-Mn austenitic steel,110Mn12Cr2NY,at temperatures ranging from 800 to 1200℃ and strain rates ranging from 0.01 to 1 s^(−1).The results revealed that the critical strain for dynamic recrystallization(DRX)lowered with increasing deformation temperature and decreasing strain rate.The analysis of microstructure pointed to discontinuous dynamic recrystallization(DDRX)as the dominant DRX mechanism,characterized byΣ3 twin boundaries and necklace-like structure during deformation at relatively low temperature and high strain rate.The decrease in strain rate facilitated continuous dynamic recrystallization(CDRX)as an auxiliary nucleation mechanism,leading to a significant decrease in the softening rate in the flow stress curves.When deformed at high temperatures and low strain rates,the preferential growth of<001>oriented grains resulted in the formation of a strong<001>//CD texture,and CDRX associated with<001>grains emerged as the predominant DRX mechanism.Significant DRX occurring at high temperatures and high strain rates yielded fine,defect-free equiaxed grains.Consequently,this region could be employed as the optimal hot working window for 110Mn12Cr2NY steel,with a temperature range of 950–1200℃and a strain rate range of 0.4^(–)1 s^(−1).
基金support of the Deutsche Forschungsgemeinschaft(DFG) within the Collaborative Research Center(SFB) 761 "Steelab initio"
文摘Austenitic high-Mn steels with Mn contents between approximately 15 and 30 wt% gain much interest because of their excellent mechanical properties and the option for adjusting strain hardening behavior due to different deformation mechanisms. 2D and 3D composition-dependent stacking fault energy （SFE） maps indicate the effect of chemical composition and temperature on SFE and consequently on the deformation mechanisms. Three steels with different chemical compositions and the same or different SFE are characterized in quasi-static tensile tests. The control parameters of strain hardening behavior in the high-Mn austenitic steels are described, and consequences for future developments are discussed.
基金supported by the Korea Institute for Advancement of Technology(KIAT)grant funded by the Korea Government(MOTIE)(Grant No.P0002019)the Korea University Grant for the fifth authorthe Brain Korea 21 PLUS Project for Center for Creative Industrial Materials。
文摘The formability of austenitic high-Mn steels is a critical issue in automotive applications under nonuniformly-deformed environments caused by dynamic strain aging.Among austenite stabilizing alloying elements in those steels,Cu has been known as an effective element to enhance tensile properties via controlling the stacking fault energy and stability of austenite.The effects of Cu addition on formability,however,have not been sufficiently reported yet.In this study,the Cu addition effects on formability and surface characteristics in the austenitic high-Mn TRIP steels were analyzed in consideration of inhomogeneous microstructures containing the segregation of Mn and Cu.To reveal determining factors,various mechanical parameters such as total elongation,post elongation,strain hardening rate,normal anisotropy,and planar anisotropy were correlated to the hole-expansion and cup-drawing test results.With respect to microstructural parameters,roles of(Mn,Cu)-segregation bands and resultant Cu-rich FCC precipitates on the formability and surface delamination were also discussed.
文摘Deformation-induced microstructures of high-Mn austenite steel was investigated by metallography,X-ray diffraction and SEM.The ε-martensite and slip-bands are deformation-in- duced on the{111} planes,and appear as thin straight laths with 60～80° alignment difference be- tween them.It was found that ε-martensite and slip bands are kinked at fcc twin boundaries with the kinked angle 35～40°.The bands of equilateral triangle in the microstructure of tensile deformation are presented.
基金the support of the National Natural Science Foundation of China(Grant Nos.52274337 and 52174317)。
文摘To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were performed.The effects of Mn and Al contents in the steel and the reaction time on the interfacial reaction were investigated.It was observed that the erosion of the MgO refractory is caused by the reaction of Al and Mn in the steel with MgO in the refractory,which would lead to the formation of(Mn,Mg)O·Al_(2)O_(3) spinel and(Mn,Mg)O solid solution.The formation mechanism of the spinel and solid solution is as follows.The Al in the steel firstly reacts with MgO in the refractory to generate MgO·Al_(2)O_(3) spinel,and then,the spinel reacts with Mn in the steel to form(Mn,Mg)O·Al_(2)O_(3) spinel.Finally,the MnO in the spinel reacts with the MgO in the inner refractory to form(Mn,Mg)O solid solution.In addition,only(Mn,Mg)O·Al_(2)O_(3) spinel is present in the interfacial reaction layer of the refractory when the Al content in the steel is sufficient.
