超細粒鋼(SUF鋼)における疲労微小き裂の発生と初期伝ぱのAFM観察
超細粒鋼(SUF鋼)における疲労微小き裂の発生と初期伝ぱのAFM観察
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超细晶粒钢（SUF钢）疲劳微裂纹萌生和初始扩展的AFM观察
DOI：
10.2472/jsms.51.801
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
忠志 石川
中科院分区：
文献类型：
--
作者：
英彦 木村;義明 秋庭;啓介 田中;淳 近藤;忠志 石川
采用先进的热机械控制工艺生产的钢板具有两个区域：平均晶粒尺寸小于2μm的超细晶表层和中等晶粒的中间区域。对由超细晶区和中晶区组成的光滑试样进行了室温轴向拉压循环疲劳试验。通过原子力显微镜观察试样表面形貌，研究了微观结构对疲劳小裂纹萌生和早期扩展的影响。在中晶粒试样中，疲劳裂纹从简单滑移线处萌生。在超细晶试样中，在疲劳裂纹萌生之前，观察到试样表面不规则形状的复杂滑移变形。疲劳裂纹在晶界处形核，并伴随着复杂的滑移变形。在裂纹扩展的早期阶段，由于晶界堵塞和裂纹偏转，超细晶试样中的裂纹扩展速率降低。
Steel plates produced by an advanced thermo-mechanical control process have two regions: the ultrafinegrained surface layer with the average grain size of less than 2μm and the intermediate region with medium-sized grains. Smooth specimens made of ultrafine-grained and medium-grained regions were fatigued under cyclic axial tension compression at room temperature. The effect of the microstructure on the initiation and the early propagation of small fatigue cracks were investigated by observing the images of specimen surfaces replicated on plastic sheets by atomic force microscopy. In the medium-grained specimens, the fatigue cracks initiated from the simple slip lines. In the ultrafine-grained specimens, complex slip deformation in the shape of irregularities of the specimen surface was observed prior to the initiation of fatigue cracks. The fatigue cracks were nucleated at the grain boundary between the grains containing the complex slip deformation. The crack propagation rate in the ultrafine-grained specimens decreases because of the grain-boundary blocking and crack deflection in an early stage of the propagation.