郝露菡肖纳敏郑成武李殿中
材料研究学报
对低碳钢在Ae3以上进行了单道次快速大形变量变形, 测定了材料在高温变形前后的室温拉伸曲线并观察其断口形貌。对结果的分析表明, 低碳钢在Ae3以上的温度发生形变诱导铁素体相变, 是形成超细晶粒(3 μm左右)的主要原因。应变速率大于0.1 s-1时, 可诱导形成铁素体晶粒, 且随着应变速率的提高铁素体分数增加而晶粒尺寸减小; 当应变速率大于10 s-1时铁素体分数达到饱和, 晶粒尺寸的变化不大。与先共析铁素体相比, 形变诱导铁素体的强度和硬度大大提高, 低碳钢Q235的屈服强度由250 MPa左右提高到510 MPa, 抗拉强度则达到615 MPa, 而形变诱导铁素体的塑性有所降低, 但仍保持较高的水平。
关键词:
金属材料
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tension mechanical properties
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deformation induced ferrite transformation
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stain rate
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low carbon steel
Z.D. Wang
,
J.B. Qu
,
X.H. Liu and G.D. Wang(State Key Lab of Rolling and Automation
,
Northeastern University
,
Shenyang 110006
,
China)
金属学报(英文版)
The influence of hot deformation conditions on continuous cooling bainitic transformation has been investigated for a low carbon microalloyed steel. The CCT diagrams show that deformation in unrecrpstallized austcnite ation can accelerate transformation process. Bainitic transformation in intermediate transformation temperature region is prominent, and the proeutectoid polygonal ferrite transformation at evelated high temperature is suppressed. According to optical and TEM analyses, low carbon bainitic ferrite is characterized by granular and lathlike ferrite, based on the cooling rate and deformation conditions. For nondeformation, groaps of coarse parallel ferrite lath form from the prior austenite grain boundaries with the same crystallographic orientation. For heavy deformaton, cell structure within the austenite grains due to the high dislocation density formed, which provides more nucleation sites for bainite ferrite. So deformation can discontinue the growth of ferrite laths and decrease the length of ferrite laths.
关键词:
bainite
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null
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