A Central Atom Model is introduced and the LFG and Hsu models are modified in order to evaluate the driving force for the martensitic transformation in Fe-Mn-C and Fe-Ni-C al- loys.The results show that the relationsh...A Central Atom Model is introduced and the LFG and Hsu models are modified in order to evaluate the driving force for the martensitic transformation in Fe-Mn-C and Fe-Ni-C al- loys.The results show that the relationship between the driving force and the yield strength of austenite at Ms temperature,σ_(0.2)~γ/M_s,fits Hsu's formula;ΔG~=2.1σ_(0.2)~γ/M_s+907 J/mol.The M_s temperatures of Fe-Mn-C and Fe-Ni-C alloys are also calculated.The calculated results are in good agreement with experimental values.展开更多
C-Mn segregation and its effect on phase transformation and plastic deformation in Fe-Mn-C alloys were studied through the calculation of valence electron structure, the microregion composition detection and TEM in-si...C-Mn segregation and its effect on phase transformation and plastic deformation in Fe-Mn-C alloys were studied through the calculation of valence electron structure, the microregion composition detection and TEM in-situ dynamic tensile deformation test The experimental results show that in Fe-8Mn-1.2C alloyed austenite, nA of units with C Mn involved is 3 98 times that of units without C involved and 1.4 times that of units with C involved; aCD of units with C-Mn involved is 2 21 times that of units with C involved. In Fe-Mn-C alloyed austenites, there exists microsegrcgation of C-Mn, forming the randomly distributed Fe-Mn-C atomic cluster segregation zone linked with the -C-Mn-C-Mn- strong bond network, which will effectively slow down the motion of atoms and retard the initiation of the slip system and the movement of dislocation, and thus will severely influence the phase transformation and deformation of the alloy展开更多
以Fe-Mn-C系TWIP钢为例,利用Gleeble-3500热模拟试验机对其塑性变形抗力进行研究。通过试验得到的数据分析了不同变形温度、变形程度、应变速率与变形抗力的关系。结果表明,试验TWIP钢热变形的应力随温度的升高而降低,随应变速率的增大...以Fe-Mn-C系TWIP钢为例,利用Gleeble-3500热模拟试验机对其塑性变形抗力进行研究。通过试验得到的数据分析了不同变形温度、变形程度、应变速率与变形抗力的关系。结果表明,试验TWIP钢热变形的应力随温度的升高而降低,随应变速率的增大而升高。TWIP钢的热变形激活能Q为194.875 k J/mol,并在此基础上得到了TWIP钢的高温流变方程。展开更多
On the basis of experimental results of 76 points of composition and previous relevant conclu- sions,a relatively complete constitutional diagram of solid solution treating Fe-Mn-C sys- tem alloy at 1000℃ has been co...On the basis of experimental results of 76 points of composition and previous relevant conclu- sions,a relatively complete constitutional diagram of solid solution treating Fe-Mn-C sys- tem alloy at 1000℃ has been constructed with austenite zones of different stabilities.The chemical composition range and structure change of steels with various Mn have also been discussed.Thus,the reasonable selection of composition and structure may be available for the manganese steel with commercial purposes.展开更多
The M_s temperature and the yield strength of austenite at M_s temperature have been meas- ured for five Fe-Mn-C alloys.The experimental results show that there is a linear relation- ship between them.The effect of th...The M_s temperature and the yield strength of austenite at M_s temperature have been meas- ured for five Fe-Mn-C alloys.The experimental results show that there is a linear relation- ship between them.The effect of the solution strengthening of austenite on martensite morphology is also studied.It is pointed out that there is a characteristic temperature T_c in austenite strengthening.Martensite morphology is mainly of dislocated laths when M_s>T_c, and is mainly of twinned plates when M_s<T_c.A theoretical analysis is given which is in good agreement with experimental results.展开更多
Fe-Mn-C-Al alloys have been recognized as promising materials for certain low-temperature applications due to their exceptional mechanical properties and cost-effectiveness.However,their limited low-temperature toughn...Fe-Mn-C-Al alloys have been recognized as promising materials for certain low-temperature applications due to their exceptional mechanical properties and cost-effectiveness.However,their limited low-temperature toughness restricts their large-scale applications in specific scenarios.The influence of trace amounts of rare earth cerium(Ce)on the low-temperature toughness of Fe-18Mn-0.6C-1.8Al alloys was investigated.The addition of Ce effectively alters the inclu-sions in the alloy,transforming large-sized irregular inclusions into fine ellipsoidal rare earth inclusions.This leads to a significant reduction in both the proportion and average size of the inclusions,resulting in their effective dispersion throughout the matrix and improved cryogenic performance.The presence of Ce-containing inclusions within the matrix reduces stress concentration,thereby inhibiting microcrack formation and improving impact absorption energy.Specifi-cally,the addition of rare earth Ce alters the fracture behavior of the material at room temperature and low temperature,changing from brittle cleavage fracture to a more ductile failure mode.The impact toughness of the Fe-Mn-C-Al alloy is significantly improved by the addition of 0.0048 wt.%Ce,particularly at-196℃where the impact toughness reaches 103.6 J/cm^(2),representing an impressive improvement of 87.3%.展开更多
文摘A Central Atom Model is introduced and the LFG and Hsu models are modified in order to evaluate the driving force for the martensitic transformation in Fe-Mn-C and Fe-Ni-C al- loys.The results show that the relationship between the driving force and the yield strength of austenite at Ms temperature,σ_(0.2)~γ/M_s,fits Hsu's formula;ΔG~=2.1σ_(0.2)~γ/M_s+907 J/mol.The M_s temperatures of Fe-Mn-C and Fe-Ni-C alloys are also calculated.The calculated results are in good agreement with experimental values.
基金Project supported by the Natural Science Foundation of Shandong Province, China
文摘C-Mn segregation and its effect on phase transformation and plastic deformation in Fe-Mn-C alloys were studied through the calculation of valence electron structure, the microregion composition detection and TEM in-situ dynamic tensile deformation test The experimental results show that in Fe-8Mn-1.2C alloyed austenite, nA of units with C Mn involved is 3 98 times that of units without C involved and 1.4 times that of units with C involved; aCD of units with C-Mn involved is 2 21 times that of units with C involved. In Fe-Mn-C alloyed austenites, there exists microsegrcgation of C-Mn, forming the randomly distributed Fe-Mn-C atomic cluster segregation zone linked with the -C-Mn-C-Mn- strong bond network, which will effectively slow down the motion of atoms and retard the initiation of the slip system and the movement of dislocation, and thus will severely influence the phase transformation and deformation of the alloy
文摘以Fe-Mn-C系TWIP钢为例,利用Gleeble-3500热模拟试验机对其塑性变形抗力进行研究。通过试验得到的数据分析了不同变形温度、变形程度、应变速率与变形抗力的关系。结果表明,试验TWIP钢热变形的应力随温度的升高而降低,随应变速率的增大而升高。TWIP钢的热变形激活能Q为194.875 k J/mol,并在此基础上得到了TWIP钢的高温流变方程。
文摘On the basis of experimental results of 76 points of composition and previous relevant conclu- sions,a relatively complete constitutional diagram of solid solution treating Fe-Mn-C sys- tem alloy at 1000℃ has been constructed with austenite zones of different stabilities.The chemical composition range and structure change of steels with various Mn have also been discussed.Thus,the reasonable selection of composition and structure may be available for the manganese steel with commercial purposes.
文摘The M_s temperature and the yield strength of austenite at M_s temperature have been meas- ured for five Fe-Mn-C alloys.The experimental results show that there is a linear relation- ship between them.The effect of the solution strengthening of austenite on martensite morphology is also studied.It is pointed out that there is a characteristic temperature T_c in austenite strengthening.Martensite morphology is mainly of dislocated laths when M_s>T_c, and is mainly of twinned plates when M_s<T_c.A theoretical analysis is given which is in good agreement with experimental results.
基金This work was supported by the National Natural Science Foundation of China(No.52164032)the Hong Kong Scholars Program(2021-077).
文摘Fe-Mn-C-Al alloys have been recognized as promising materials for certain low-temperature applications due to their exceptional mechanical properties and cost-effectiveness.However,their limited low-temperature toughness restricts their large-scale applications in specific scenarios.The influence of trace amounts of rare earth cerium(Ce)on the low-temperature toughness of Fe-18Mn-0.6C-1.8Al alloys was investigated.The addition of Ce effectively alters the inclu-sions in the alloy,transforming large-sized irregular inclusions into fine ellipsoidal rare earth inclusions.This leads to a significant reduction in both the proportion and average size of the inclusions,resulting in their effective dispersion throughout the matrix and improved cryogenic performance.The presence of Ce-containing inclusions within the matrix reduces stress concentration,thereby inhibiting microcrack formation and improving impact absorption energy.Specifi-cally,the addition of rare earth Ce alters the fracture behavior of the material at room temperature and low temperature,changing from brittle cleavage fracture to a more ductile failure mode.The impact toughness of the Fe-Mn-C-Al alloy is significantly improved by the addition of 0.0048 wt.%Ce,particularly at-196℃where the impact toughness reaches 103.6 J/cm^(2),representing an impressive improvement of 87.3%.
