抗磨贝氏体球铁的裂纹形核与扩展

采用压痕法及扫描电镜观察,研究了抗磨贝氏体球铁中裂纹的形核与扩展。实验结果表明,裂纹主要在石墨─基体界面形成,其次在碳化物─基体界面形核。裂纹在石墨─基体界面和碳化物─基体界面的形成机制不同,裂纹优先沿界面扩展。并从热力学的角度对其进行了分析。

Crack nucleation and propagation in wear-resistant bainite ductile cast iron

Crack nucleation and propagation in wear-resistant bainite ductile cast iron were investigated by press trace method and SEM. The results indicated that crack nucleated mainly in the interface of graphite-matrix and in the interface of carbide-matrix, and the former is easier than the later. But the nucleation mechanism was different. The graphite nodular, as a "hole" of the matrix for its low shear modulus, will attract dislocations other than hinder them. Thus it will decrease the elastic energy of the dislocation. The crack nucleated in the other side of the interface of graphite-matrix, which is far away from dislocation, along the direction of dislocation motion. But carbide will hinder the movement of dislocation, and the crack nucleated in the front side of the interface of carbide-matrix.The crack was propagated along the interface path forward and was analyzed in thermodynamic aspect.