表面强化材料的韧性对疲劳性能及断裂性质的影响

Influence of Toughness on Fatigue and Fracture Properties of Matericals

对45钢正火态软氮化处理前后的旋转弯曲疲劳性能及其断口进行了定量和电镜分析。从断裂力学观点分析了疲劳最后断裂性质。结果表明:疲劳最后断裂性质取决于材料的强度和韧性。同时,冲击疲劳试验表明:软氮化处理使冲击疲劳性能劣化,这是因表面硬化层约束了柔软心部,使整体材料的韧性变差的结果。因此,表面硬化处理时,在保证设计要求的条件下,尽量减少层深,以保证材料有适应的韧塑性。

The bending fatigue properties and fractography of normalized tufftrided 45 steel were analyzed. Based on fracture mechanics approach, the fracture properties were studied. It is shown that the fracture properties are determined by materials strength before tufftride process and by materials toughness after tufftride process. The impact fatigue tests show that the tufftride process has a bad influance on impact fatigue properties of materials. It is suggested that the hardened layer should be as thin as the possible to guarantee favarable plasticity and toughness under the condition that the surface properties can meet the demoned of desigus.