Two kinds of low-carbon low-silicon TRIP (Transformation Induced Plasticity) steels containing vanadium are designed using ThermoCalc software in the light of both thermodynamics and kinetics.TRIP heat treatment proce...Two kinds of low-carbon low-silicon TRIP (Transformation Induced Plasticity) steels containing vanadium are designed using ThermoCalc software in the light of both thermodynamics and kinetics.TRIP heat treatment process of different steels is determined according to the calculation results respectively.Weld HAZ (Heat-Affected Zone) simulation tests indicate the weldability of TRIP steels is crucially sensitive to CE (carban equivelent) of the steel.However the impact toughness of CGHAZ (Coarse Grain Heat-Affected Zone) does not decrease drastically for TRIP steels microalloyed with Ti+V.The steel containing both of vanadium and titanium shows smaller grain size compared with that containing vanadium solely.This is because the precipitation of Ti/V carbonitride slows down the grain boundary motion speed and then retards the grain size coalescence in CGHAZ.展开更多
Silicon is an essential alloying element in quenching and partitioning(Q&P)steels,because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize austeni...Silicon is an essential alloying element in quenching and partitioning(Q&P)steels,because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize austenite.When 2 wt%Si was added to 10Mn-2Al-0.2C steel,the size and fraction of the carbides formed during partitioning became smaller than in the Si-free counterpart.Moreover,the suppression of carbide formation promoted C partitioning into austenite as expected.However,austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of austenite.As partitioning progressed,the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility level.This was because Si was an effective solid solution strengthener,and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the deformation.The resulting strengthening effect compensated for the softening caused by martensite recovery.Consequently,strain hardening rate decreased continuously throughout deformation,which resulted in high tensile strength and ductility.展开更多
基金financially supported by VANITECNSFC(No.50971137.)
文摘Two kinds of low-carbon low-silicon TRIP (Transformation Induced Plasticity) steels containing vanadium are designed using ThermoCalc software in the light of both thermodynamics and kinetics.TRIP heat treatment process of different steels is determined according to the calculation results respectively.Weld HAZ (Heat-Affected Zone) simulation tests indicate the weldability of TRIP steels is crucially sensitive to CE (carban equivelent) of the steel.However the impact toughness of CGHAZ (Coarse Grain Heat-Affected Zone) does not decrease drastically for TRIP steels microalloyed with Ti+V.The steel containing both of vanadium and titanium shows smaller grain size compared with that containing vanadium solely.This is because the precipitation of Ti/V carbonitride slows down the grain boundary motion speed and then retards the grain size coalescence in CGHAZ.
基金POSCO(Pohang,Republic of Korea)for the financial supportsupported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(2019R1I1A3A0106262212).
文摘Silicon is an essential alloying element in quenching and partitioning(Q&P)steels,because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize austenite.When 2 wt%Si was added to 10Mn-2Al-0.2C steel,the size and fraction of the carbides formed during partitioning became smaller than in the Si-free counterpart.Moreover,the suppression of carbide formation promoted C partitioning into austenite as expected.However,austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of austenite.As partitioning progressed,the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility level.This was because Si was an effective solid solution strengthener,and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the deformation.The resulting strengthening effect compensated for the softening caused by martensite recovery.Consequently,strain hardening rate decreased continuously throughout deformation,which resulted in high tensile strength and ductility.
