Instead of conventional quenching and tempering,fast austenitization from an initial microstructure of lamellar pearlite followed by quenching and tempering was carried out,leading to the formation of inhomogeneous mi...Instead of conventional quenching and tempering,fast austenitization from an initial microstructure of lamellar pearlite followed by quenching and tempering was carried out,leading to the formation of inhomogeneous microstructure.It comprised different morphologies of lath martensite and retained austenite(RA).The effect of tempering temperature on microstructure evolution and tensile properties was systematically investigated.With increasing tempering temperature from 150 to 250℃,transition carbides gradually coarsened and their amount increased,the dislocation density in martensitic laths gradually decreased,and RA fraction decreased from 10.9%to 2.2%.The precipitation and dislocation strengthening can ensure a high strength,while RA can ensure a good ductility,leading to a simultaneous increase in the strength and ductility when decreasing tempering temperature.Specifically,the best combination of tensile properties(ultimate tensile strength of 2133±41 MPa and total elongation of 11.1%±1.3%)was achieved after tempering at 150℃.展开更多
Chemical heterogeneity in high-temperature austenite is an effective way to tune the austenite-to-martensite transformation during cooling.The effect of quenching temperature on microstructure evolution is investigate...Chemical heterogeneity in high-temperature austenite is an effective way to tune the austenite-to-martensite transformation during cooling.The effect of quenching temperature on microstructure evolution is investigated when the high-temperature austenite is heterogeneous.After fast austenitization from partitioned pearlite consisting of Mn-enriched cementite and Mn-depleted ferrite in Fe-0.29C-3.76Mn-1.50Si(wt.%)steel,quenching to room temperature and quenching to 130℃ followed by 400℃ partitioning are both applied.With increasing quenching temperature from 25 to 130℃,the amount of heterogeneous microstructure(lamellar ghost pearlite)increases from 10.6%to 33.6% and the thickness of Mn-enriched retained austenite film is increased from 31.9±5.9 to 51.5±4.4 nm,indicating an enhancement of chemical patterning.It is probably ascribed to the reduction in driving force for austenite-to-martensite transformation,which requires a lower Mn content for austenite retention.展开更多
基金support from the National Natural Science Foundation of China(5190102i)the"Beijing Institute of Technology Research Fund Program for Young Scholars".
文摘Instead of conventional quenching and tempering,fast austenitization from an initial microstructure of lamellar pearlite followed by quenching and tempering was carried out,leading to the formation of inhomogeneous microstructure.It comprised different morphologies of lath martensite and retained austenite(RA).The effect of tempering temperature on microstructure evolution and tensile properties was systematically investigated.With increasing tempering temperature from 150 to 250℃,transition carbides gradually coarsened and their amount increased,the dislocation density in martensitic laths gradually decreased,and RA fraction decreased from 10.9%to 2.2%.The precipitation and dislocation strengthening can ensure a high strength,while RA can ensure a good ductility,leading to a simultaneous increase in the strength and ductility when decreasing tempering temperature.Specifically,the best combination of tensile properties(ultimate tensile strength of 2133±41 MPa and total elongation of 11.1%±1.3%)was achieved after tempering at 150℃.
基金Zhi-ping Xiong thanks the financial support from the National Natural Science Foundation of China(52271004 and 51901021)the"Beijing Institute of Technology Research Fund Program for Young Scholars".
文摘Chemical heterogeneity in high-temperature austenite is an effective way to tune the austenite-to-martensite transformation during cooling.The effect of quenching temperature on microstructure evolution is investigated when the high-temperature austenite is heterogeneous.After fast austenitization from partitioned pearlite consisting of Mn-enriched cementite and Mn-depleted ferrite in Fe-0.29C-3.76Mn-1.50Si(wt.%)steel,quenching to room temperature and quenching to 130℃ followed by 400℃ partitioning are both applied.With increasing quenching temperature from 25 to 130℃,the amount of heterogeneous microstructure(lamellar ghost pearlite)increases from 10.6%to 33.6% and the thickness of Mn-enriched retained austenite film is increased from 31.9±5.9 to 51.5±4.4 nm,indicating an enhancement of chemical patterning.It is probably ascribed to the reduction in driving force for austenite-to-martensite transformation,which requires a lower Mn content for austenite retention.
