| Relaxation of Deformed Austenite and Refinement of Bainite in a Nb-Containing Microalloyed Steel |
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| 作者单位： | Shanwu Yang，Xuemin Wang，Chengjia Shang，Xinlai He，Yi Yuan Material Science and Engineering School，University of Science and Technology Beijing，Beijing 100083，China |
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| 摘 要： |
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Relaxation of Deformed Austenite and Refinement of Bainite in a Nb-Containing Microalloyed Steel |
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| Authors: | Shanwu Yang Xuemin Wang Chengjia Shang Xinlai He Yi Yuan |
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| Abstract: | By means of stress relaxation and strain-induced precipitation in deformed austenite, bainite with micron sheaves size was ob-tained in Nb-containing steel. Microstructures of deformed samples isothermally relaxed for various time followed by cooling in water were examined. Stress relaxation test and transmission electron microscopy (TEM) were employed to detect precipitation of microalloy elements, such as Nb, Ti, during isothermal holding after deformation. All the samples were constituted by lath-like bainite along with acicular ferrite, but the size of bainitic sheaves and the amount of acicular ferrite were changed with relaxation time. To achieve optimum refinement, relaxation should be confined in the stage when the precipitates have sufficiently grown and started to coarsen. The sample having not undergone relaxation does not exhibit obvious refinement despite of its higher dislocation density. These results indicate that relaxation promotes bainite to refine, which is because deformed austenitic grains are divided by dislocation walls formed during rela-xation and acicular ferrite formed before bainitic transformation. |
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| Keywords: | stress relaxation strain induced precipitation refinement |
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