Effect of rare earth metals (REM) on tempering process and decomposition kinetics of martensite and retained austenite of high carbon steel were investigated by DSC technique,based on the non-isothermal kinetic theory...Effect of rare earth metals (REM) on tempering process and decomposition kinetics of martensite and retained austenite of high carbon steel were investigated by DSC technique,based on the non-isothermal kinetic theory.The result shows that the addition of REM in high carbon steel increases the decomposition temperatures of martensite and retained austenite,decreases the thennal effect values,elevates the activity energies and changes the transformation mechanism.展开更多
The microstructures and mechanical properties of deformation induced ferrite （DIF） in the low carbon steel Q235 under different deformation temperatures have been investigated systematically. Through deformation ind...The microstructures and mechanical properties of deformation induced ferrite （DIF） in the low carbon steel Q235 under different deformation temperatures have been investigated systematically. Through deformation induced ferrite transformation （DIFT）, ferrite grain can be refined to 3 μm and accounts for above 85% of the overall fraction. Yield strength of DIF （〉500 MPa） is increased by up to 100% compared with the conventional low carbon steel. Comparison of microstructure and mechanical properties in the Q235 steel with DIF and tempered DIF microstructure illustrates that the strengthening mechanism of DIF microstructure is the combination of grain boundary strengthening and carbon supersaturated strengthening. Electron back-scattered diffraction （EBSD） analysis and high magnification scanning electron microscopy （SEM） observation denote that high-angle grain boundary among ultrafine ferrite grain and the transformation product of retain austenite membrane along ferrite boundaries are responsible for the stability of ferrite grain size during tempering process. Transmission electron microscopy （TEM） analysis demonstrates that the transformation product of retained austenite membrane between ferrite grain boundaries is cementite.展开更多
文摘Effect of rare earth metals (REM) on tempering process and decomposition kinetics of martensite and retained austenite of high carbon steel were investigated by DSC technique,based on the non-isothermal kinetic theory.The result shows that the addition of REM in high carbon steel increases the decomposition temperatures of martensite and retained austenite,decreases the thennal effect values,elevates the activity energies and changes the transformation mechanism.
基金supported by the National Natural Science Foundation of China (NSFC) under Grant No. 50871109
文摘The microstructures and mechanical properties of deformation induced ferrite （DIF） in the low carbon steel Q235 under different deformation temperatures have been investigated systematically. Through deformation induced ferrite transformation （DIFT）, ferrite grain can be refined to 3 μm and accounts for above 85% of the overall fraction. Yield strength of DIF （〉500 MPa） is increased by up to 100% compared with the conventional low carbon steel. Comparison of microstructure and mechanical properties in the Q235 steel with DIF and tempered DIF microstructure illustrates that the strengthening mechanism of DIF microstructure is the combination of grain boundary strengthening and carbon supersaturated strengthening. Electron back-scattered diffraction （EBSD） analysis and high magnification scanning electron microscopy （SEM） observation denote that high-angle grain boundary among ultrafine ferrite grain and the transformation product of retain austenite membrane along ferrite boundaries are responsible for the stability of ferrite grain size during tempering process. Transmission electron microscopy （TEM） analysis demonstrates that the transformation product of retained austenite membrane between ferrite grain boundaries is cementite.
