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本文借助于图象分析技术使用Slit island方法研究了两种高强度钢不同热处理制度和不同试验温度条件下平面应变断裂表面的分形维数.结果表明,断裂表面是一种分形结构,断裂韧性K_(IC)值的对数随分形维数D_F增加成单调下降的直线关系.这种关系反映了不同热处理制度所引起的材料微观结构变化和不同试验温度所引起的断裂机制变化,D_F可以做为金属断裂韧性的一种度量。最后,用临界裂纹扩展力与不规则断裂表面真实面积之间的关系对结果进行了理论分析.
In this paper, fractal dimension of plane strain fracture surface under different heat treatment regimes and different test temperatures of two high strength steels was studied by means of image analysis technique using Slit island method.The results show that fracture surface is a kind of fractal structure, fracture toughness K_ (IC) logarithm increases linearly with the fractal dimension D_F to decrease monotonically.The relationship reflects the change of microstructure of materials and the fracture mechanism caused by different test temperatures caused by different heat treatment systems, and D_F can be used as A measure of metal fracture toughness. Finally, the theoretical analysis is made on the relationship between the critical crack propagation force and the true area of the irregular fracture surface.