【摘要】 本文指出,用断裂力学参数代替冲击韧性更能正确反映球铁承受静、动载荷抗断能力。介绍了稀土镁球铁K_Ic,da/dN,△K_th等参数的测定方法和特点,研究了金相组织如球化率、石墨形态、球径、基体组织等对球铁断裂韧性的影响,对强韧球铁应具有的冶金结构进行了探讨。同时,对疲劳断裂过程各个阶段的裂纹扩展特性进行了观察。作者认为,改善球铁的金相组织有可能在强度和韧性方面出现较大突破。更多还原

【Abstract】 The endurance of rare earth-magnesium nodular cast iron to fracture under static and dynamic loads is shown to be more accurately represented by the parameters of fracture mechanics rather than by impact toughness. Parameters such as K_Ic, da/dN and AK_th are represented. With a view to clarifying the effect of various metallographic structures upon the fracture toughness of the material, the rate of spheroidization, the morphology of graphite, the size of spherulites, the matrix structure, etc. were separately examined. At the same time, crack propagation characteristics for different stages of fatigue fracture were also investigated. It is recommended that nodular cast iron could be in greater strength and better toughness provided that its microstructure is improved.更多还原