The microstructure evolution during strain induced ferrite transformation was followed in thermal-simulation tests of clean 08 and 20Mn steels. The influences of carbon equivalence and initial austenite grain size on ...The microstructure evolution during strain induced ferrite transformation was followed in thermal-simulation tests of clean 08 and 20Mn steels. The influences of carbon equivalence and initial austenite grain size on ferrite grain refinement and the volume frac- tion of ferrite during straining were inspected. The results revealed that the accelerating effect of ferrite transformation by strain was increased as the carbon equivalence decreased. However, finer ferrite grains were obtained at higher carbon content. At strain of -1 .5 ferrite grains less than 3 μm and 2 μm can be obtained in 08 and 20Mn steels respectively. Whereas the ferrite grain refinement in 08 steel was due to both effects of strain induced transformation and ferrite dynamic recrystallization, that in 20Mn was mainly due to st fain induced transformation. Heavy strain can produce fine ferrite grains in coarse austenite grained 08 steel, but it would lead to band microstructure in coarse austenite grained 20Mn.展开更多
The influence of deforming temperature on ferrite refinement was analyzed by comparing the microstructures obtained by de-formation at above Ar3, in two-phase region of(α+γ) and at below A1 in clean 08 and 20Mn stee...The influence of deforming temperature on ferrite refinement was analyzed by comparing the microstructures obtained by de-formation at above Ar3, in two-phase region of(α+γ) and at below A1 in clean 08 and 20Mn steels. The results indicate that ferrite refinement through strain induced transformation by deformation at above Ar3 is more effective than that by deformation simply through ferrite dynamic recrystallization. The main problem of ferrite refinement by deformation at below Ar3 is the inhomogeneity of microstructure which is controlled by the orientations and sizes of ferrite grains and the distribution of second phases. Ferrite dynamic recrystallization after strain induced transformation can further effectively refine ferrite.展开更多
文摘The microstructure evolution during strain induced ferrite transformation was followed in thermal-simulation tests of clean 08 and 20Mn steels. The influences of carbon equivalence and initial austenite grain size on ferrite grain refinement and the volume frac- tion of ferrite during straining were inspected. The results revealed that the accelerating effect of ferrite transformation by strain was increased as the carbon equivalence decreased. However, finer ferrite grains were obtained at higher carbon content. At strain of -1 .5 ferrite grains less than 3 μm and 2 μm can be obtained in 08 and 20Mn steels respectively. Whereas the ferrite grain refinement in 08 steel was due to both effects of strain induced transformation and ferrite dynamic recrystallization, that in 20Mn was mainly due to st fain induced transformation. Heavy strain can produce fine ferrite grains in coarse austenite grained 08 steel, but it would lead to band microstructure in coarse austenite grained 20Mn.
基金the University of Scoence and Technology Beijing on the project 'Supersteel'.]
文摘The influence of deforming temperature on ferrite refinement was analyzed by comparing the microstructures obtained by de-formation at above Ar3, in two-phase region of(α+γ) and at below A1 in clean 08 and 20Mn steels. The results indicate that ferrite refinement through strain induced transformation by deformation at above Ar3 is more effective than that by deformation simply through ferrite dynamic recrystallization. The main problem of ferrite refinement by deformation at below Ar3 is the inhomogeneity of microstructure which is controlled by the orientations and sizes of ferrite grains and the distribution of second phases. Ferrite dynamic recrystallization after strain induced transformation can further effectively refine ferrite.
