The microstructural evolution and precipitation behaviour of Nb–V–Mo and single V containing transformation induced plasticity assisted steels were investigated during thermomechanical processing. A plane strain com...The microstructural evolution and precipitation behaviour of Nb–V–Mo and single V containing transformation induced plasticity assisted steels were investigated during thermomechanical processing. A plane strain compression testing machine was used to simulate the thermomechanical processing. Microstructures were characterised by optical microscopy, scanning-transmission electron microscopy and microanalysis, and X-ray diffraction analysis, and Vickers hardness was obtained from the deformed specimens. The resulting microstructure of both Nb–V–Mo and V steels at room temperature primarily consisted of an acicular/bainitic ferrite, retained austenite and martensite surrounded by allotriomorphic ferrite.The TEM analysis showed that a significant number of Nb（V,Mo）（C,N） precipitates were formed in the microstructure down to the finishing stage in Nb–V–Mo steel（i.e. 830℃）. It was also found that the V（C,N）precipitation primarily occurred in both ferrite and deformed austenite below the finishing stage. The results suggested that Nb–Mo additions considerably increased the temperature stability of microalloy precipitates and controlled the microstructural evolution of austenite. However, the microalloy precipitation did not cause a significant precipitation strengthening in both Nb–V–Mo and V steels at room temperature.展开更多
The variant selection of martensites（ε-M and α＇-M） and ε-M reversion in dynamic tensile high-manganese TRIP steel were investigated. α＇-M variant pairs with a zigzag morphology frequently formed, and the pairs...The variant selection of martensites（ε-M and α＇-M） and ε-M reversion in dynamic tensile high-manganese TRIP steel were investigated. α＇-M variant pairs with a zigzag morphology frequently formed, and the pairs of neighboring α＇-M variants were examined in terms of mechanical work and strain energy reduction. The occurrence of a primary α＇-M variant is determined by mechanical work, but high products of mechanical work and strain energy reduction are essential for secondary variant selection. In contrast to α＇-M variant pair selection, ε-M variant selection can be attributed to the highest mechanical work. During ε-M→α＇-M transformation, the mechanical work of ε-M reversion is higher than that of α＇-M variant, thereby implying that ε-M reversion in h110 icgrain is possible. e-M plate distribution also affects the feasibility of ε-M reversion.展开更多
文摘The microstructural evolution and precipitation behaviour of Nb–V–Mo and single V containing transformation induced plasticity assisted steels were investigated during thermomechanical processing. A plane strain compression testing machine was used to simulate the thermomechanical processing. Microstructures were characterised by optical microscopy, scanning-transmission electron microscopy and microanalysis, and X-ray diffraction analysis, and Vickers hardness was obtained from the deformed specimens. The resulting microstructure of both Nb–V–Mo and V steels at room temperature primarily consisted of an acicular/bainitic ferrite, retained austenite and martensite surrounded by allotriomorphic ferrite.The TEM analysis showed that a significant number of Nb（V,Mo）（C,N） precipitates were formed in the microstructure down to the finishing stage in Nb–V–Mo steel（i.e. 830℃）. It was also found that the V（C,N）precipitation primarily occurred in both ferrite and deformed austenite below the finishing stage. The results suggested that Nb–Mo additions considerably increased the temperature stability of microalloy precipitates and controlled the microstructural evolution of austenite. However, the microalloy precipitation did not cause a significant precipitation strengthening in both Nb–V–Mo and V steels at room temperature.
基金financially supported by the National Natural Science Foundation of China (No. 51271028)
文摘The variant selection of martensites（ε-M and α＇-M） and ε-M reversion in dynamic tensile high-manganese TRIP steel were investigated. α＇-M variant pairs with a zigzag morphology frequently formed, and the pairs of neighboring α＇-M variants were examined in terms of mechanical work and strain energy reduction. The occurrence of a primary α＇-M variant is determined by mechanical work, but high products of mechanical work and strain energy reduction are essential for secondary variant selection. In contrast to α＇-M variant pair selection, ε-M variant selection can be attributed to the highest mechanical work. During ε-M→α＇-M transformation, the mechanical work of ε-M reversion is higher than that of α＇-M variant, thereby implying that ε-M reversion in h110 icgrain is possible. e-M plate distribution also affects the feasibility of ε-M reversion.
