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
Effect of boron on microstructure and toughness of simulated CGHAZ of 790 MPa grade HSLA steel was studied.In the CGHAZ,boron improved the toughness of granular bainite(Bg),but deteriorated that of martensite.The maj...Effect of boron on microstructure and toughness of simulated CGHAZ of 790 MPa grade HSLA steel was studied.In the CGHAZ,boron improved the toughness of granular bainite(Bg),but deteriorated that of martensite.The major reason of boron improving toughness of Bg was to reduce the.quantity of M-A constituents.The reasons of martensitic brittleness in microstructure were discussed in detail.The experimental results proved that the order state of dislocations was an important factor of martensitic brittleness caused by boron, and the higher the order degree of dislocations was, the more brittle the martensite was.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.
文摘Effect of boron on microstructure and toughness of simulated CGHAZ of 790 MPa grade HSLA steel was studied.In the CGHAZ,boron improved the toughness of granular bainite(Bg),but deteriorated that of martensite.The major reason of boron improving toughness of Bg was to reduce the.quantity of M-A constituents.The reasons of martensitic brittleness in microstructure were discussed in detail.The experimental results proved that the order state of dislocations was an important factor of martensitic brittleness caused by boron, and the higher the order degree of dislocations was, the more brittle the martensite was.
