Ultrastrong steels are widely used to manufacture load-bearing components in the automotive and aerospace industries,for light-weighting,enhanced fuel efficiency,and reduced costs.A martensitic steel with fine grains,...Ultrastrong steels are widely used to manufacture load-bearing components in the automotive and aerospace industries,for light-weighting,enhanced fuel efficiency,and reduced costs.A martensitic steel with fine grains,containing 0.34 wt%carbon and 2.85 wt%alloying elements,was produced through the combined technique of thermomechanical controlled processing,austenitizing,water quenching,and tempering(TMCP-Q&T).A lath martensitic matrix with high-density dislocations,accompanied by the twinned martensite and retained austenite,was obtained using this technique.The dispersed nano sc aleε-carbide and(Ti,Mo)C phases were distributed at both boundaries and interiors of martensite laths.The mean size of prior-austenite grains was refined to 7.7μm,and the average width of martensite laths was 190 nm.Notably,the novel steel exhibited an excellent combination of ultimate tensile strength(2.2 GPa)and ductility(9.4%),which were superior to those of 300 M steel(2 GPa,8%).Moreover,a significant 40%reduction in the alloying element content was achieved relative to 300 M steel,and the raw material cost was decreased by 17%correspondingly.The enhanced tensile strength of this martensitic steel is mainly attributed to dislocation strengthening and precipitation strengthening,which contribute 53%and 21%to the yield strength,respectively.This discovery provides a new strategy for fabricating a 2.2-GPa grade ultrastrong steel with good ductility at a low cost,making it highly desirable for industrial applications.展开更多
基金financially supported by the National Natural Science Foundation of China(No.92163215)the Natural Science Foundation for Post-doctoral Scientists of China(No.2023M741700)+2 种基金the Natural Science Foundation for Post-doctoral Scientists of Zhejiang Province(No.ZJ2023036)the Applied Basic Research Program of Changzhou City(No.CJ20235066)the Innovation Leading Talent Project of Changzhou City(No.CQ20230114)
文摘Ultrastrong steels are widely used to manufacture load-bearing components in the automotive and aerospace industries,for light-weighting,enhanced fuel efficiency,and reduced costs.A martensitic steel with fine grains,containing 0.34 wt%carbon and 2.85 wt%alloying elements,was produced through the combined technique of thermomechanical controlled processing,austenitizing,water quenching,and tempering(TMCP-Q&T).A lath martensitic matrix with high-density dislocations,accompanied by the twinned martensite and retained austenite,was obtained using this technique.The dispersed nano sc aleε-carbide and(Ti,Mo)C phases were distributed at both boundaries and interiors of martensite laths.The mean size of prior-austenite grains was refined to 7.7μm,and the average width of martensite laths was 190 nm.Notably,the novel steel exhibited an excellent combination of ultimate tensile strength(2.2 GPa)and ductility(9.4%),which were superior to those of 300 M steel(2 GPa,8%).Moreover,a significant 40%reduction in the alloying element content was achieved relative to 300 M steel,and the raw material cost was decreased by 17%correspondingly.The enhanced tensile strength of this martensitic steel is mainly attributed to dislocation strengthening and precipitation strengthening,which contribute 53%and 21%to the yield strength,respectively.This discovery provides a new strategy for fabricating a 2.2-GPa grade ultrastrong steel with good ductility at a low cost,making it highly desirable for industrial applications.
