PRECIPITATION BEHAVIOR OF NANOMETER-SIZED CARBIDES IN A Nb-Ti-BEARING LOW-CARBON STEEL
The microstructure,mechanical property and precipitation behavior in a low carbon Nb-Ti micro-alloyed steel were investigated using dilatometer,optical microscopy and transmission electron microscope.The results show that the microstructure of the experimental steel treated by isothermal quenching process mainly consists of ferrite and martensite.The volume fraction of ferrite increases with a decrease in the isothermal temperature.It is found that both of interphase precipitation and supersaturated precipitation would appear in the samples treated by isothermal quenching process.Along with the isothermal temperature decreasing,the precipitation state changes from interphase precipitation to supersaturated precipitation.The interphase precipitation of these carbides with different row spacing and different orientation in ferrite grains,is related to the mobility of interfaces during/transformation based on ledge mechanism.In addition to ”110” plane suggested by the ledge mechanism,the planar sheets of interphase precipitation are also found to be parallel with”035” planes.Moreover,the interphase precipitation carbides were identified to have a NaCl-type crystal structure with a lattice parameter of 0.432 nm and obey the Baker–Nutting(B–N)orientation relationship with respect to ferrite matrix.The contribution of the precipitation hardening to the yield strength of the experiment steel has been estimated to be~337 MPa at 620℃,based on Orowan mechanism.
HSLA steel Interphase precipitation Supersaturated precipitation Orientation relationship
LI Xiaolin WANG Zhaodong DENG Xiangtao YANG Yong SONG Dan WANG Guodong
State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China Research Institute,Northeastern University,Shenyang 110819,China
国内会议
杭州
英文
223-228
2015-11-11（万方平台首次上网日期，不代表论文的发表时间）