晶粒粗大及晶间网状铁素体强烈降低材料的裂纹扩展阻力，并极易导致裂纹的失稳扩展。
Coarsening grain and intercrystalline network ferrite depress crack growth resistance of the materials strongly and result in unstable propagation of crack very easily.
此外，显微组织中网状、块状铁素体的存在以及螺纹表层脱碳使连接螺栓疲劳强度下降也是造成断裂的重要原因。
The existence of reticulation and mass shape ferrite, decarbonization at the screw thread surface layer which induced decline of fatigue strength of connecting bolt were also…
结果表明，冷却不足使组织中出现网状及小块状铁素体，导致硬度偏低，加之磨削加工痕迹较粗是引起前轮毂早期断裂的原因。
Results showed that ferrite net and lower hardness due to low cooling rate, coarser finish machining resulted in the fracture during earlier stage of rotary bending fatigue test.
应用推荐