论文部分内容阅读
测定了34CrMoA转子钢循环蠕变断口不同放大倍数下的二次电子线扫描图象的分形维数,分析、比较了分形维数与测量尺度和蠕变速率的关系。实验结果表明,在小尺度范围内,断口表面具有统计自相似分形的特征,而在大尺度范围内则满足非一致分形的特征。因此,用一个分形维数无法完全描述断口的几何形貌,不同尺度范围内得到的分形维数值反映了断裂表面不同微观结构的不规则程度。最小蠕变速率随分形维数的变化规律也与测量尺度有关。
The fractal dimension of secondary electron scanning images at different magnification of 34CrMoA rotor steel was measured, and the relationship between fractal dimension and measurement scale and creep rate was compared. The experimental results show that in the small scale range, the fracture surface has the characteristics of self-similar fractal, while the non-uniform fractal in the large scale. Therefore, the fracture geometry can not be completely described by a fractal dimension. The fractal dimension values obtained in different scales reflect the irregularities of different microstructures on the fracture surface. The variation of minimum creep rate with the fractal dimension is also related to the measurement scale.