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Tang M.-H.,Central South University | Tang M.-H.,Hunan Institute of Engineering | Liu Z.-Y.,Central South University | Deng B.,Hunan Institute of Engineering | And 2 more authors.
Cailiao Gongcheng/Journal of Materials Engineering | Year: 2010

In order to deeply understand the mechanism of ultrafine grain of the low carbon steel obtaining ZrC particles, the effects of ZrC particles on ferrite grain refinement and basic characteristics of ferrite nucleating for this steel after deformation induced ferrite transformation at ZrC/austenitic interface were investigated by uniaxial hot compression simulation experiment. The results show that ZrC particles with definite size and suitable volume fraction dispersing in the matrix phase can hinder the movement of dislocation, form concentrated deformation zone and speed up the process of deformation induced ferrite transformation, thus increasing the nucleation rate of ferrite, resulting in ultrafine grain. The deformation induced ferrite transformation at ZrC/austenitic interface has shaped the unsaturated nature of nuclear position and the new α-phase has the characteristics of ultra-fine grain. In the strain conditions, the ferrite grains in the direction of <111> preferred orientation, a certain amount of small angle grain boundaries exist within ferrite grains, as the occurrence of ferrite dynamic recrystallization, ferrite further refinement, so the micro-mechanism of the testing steel is results of the role of the three, including the deformation induced ferrite transformation, ferrite dynamic recrystallization and dispersion strengthening of ZrC particle at the same time.


Tang M.-H.,Central South University | Tang M.-H.,Hunan Institute of Engineering | Liu Z.-Y.,Central South University | Hu S.-K.,Hunan Hengyang Steel Tube Group Co. | And 2 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2010

The effects of addition of ZrC particles on microstructure and mechanical properties of a low carbon manganese steel treaed by deformation induced ferrite transformation(DIFT) were investigated by unidirectional compression thermal simulating experiment on a Gleeble-1500 machine, and the plain C-Mn steel plate with ultra-fine grained ferrite was fabricated. The results show that adding ZrC particles with diameter less-than 1.0 μm strengthens the steel by multiplication of dislocations in matrix and ferrite grain refinement due to non-uniform deformation at ZrC/austenite interface. The fine microstructure with a grain size of 3.9 μm is obtained for the plate with thickness of 9 mm fabricated using the low carbon mangnese steel containing 0.5 vol%. ZrC particles with diameter of 0.4 μm. Tensile strength of the steel increases by 51% compared with that of commercial steel 20Mn2.


Tang M.-H.,Central South University | Tang M.-H.,Hunan Institute of Technology | Liu Z.-Y.,Central South University | Hu S.-K.,Hunan Hengyang Steel Tube Group Co. | And 2 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2010

The transitional dynamic relations of deformation induced ferrite transformation of low carbon manganese (niobium) steel containing ZrC particles under unidirectional compression thermal simulating condition were investigated. The results show that nucleation rate at austenite grain boundaries of the tested steel increases when ZrC particles are added, which affects deformation-induced ferrite morphology, distribution and its refinement. The increase of amount of the deformation induced ferrite is due to deformation enhancement in phase transformation. The decrease of size of deformation induced ferrite is due to the enhancement of recrystallization. And the deformation of the tested steel at low temperature in TAe3-TAr3 can accelerate ferrite nucleating. Meanwhile, as the deformation and recrystallization nucleus, ZrC particles with definite radius and suitable volume fraction (<0.6%), can hinder the movement of dislocation and can increase dislocation density, thus improve α-Fe nucleating rate, the critical volume fraction of ZrC particles is 0.6% which leads to the further refinement of ferrite grains of the tested steel at 900°C and strain rate of 1 s-1.

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