45^#钢试件疲劳损伤的磁记忆检测

Magnetic Memory Testing for Fatigue Damage of 45# Steel Specimen

通过对45#钢U型缺陷平板试件反复加载-卸载的疲劳试验数据进行分析,测量了试件表面法向的漏磁场分布,分析了U型缺陷对磁记忆信号的影响,以及固定位置的磁场值随循环次数的变化关系。发现试件在15万次循环周次时(最终循环周次的30%左右)磁记忆信号出现反转现象。将磁信号特征参量Kmax的变化规律与损伤力学模型中材料损伤参量D进行对比后发现,材料损伤参量D可以通过磁信号特征参量Kmax进行表述,为金属磁记忆检测技术用于评估材料的疲劳损伤程度做了一定的铺垫。

Tablet samples of 45^# steel with U-type defects were tested under repeated loading and unloading for fatigue test and were analyzed by measuring the leakage magnetic field of the sample surface normal distribution. The effect of U-shaped defects on the magnetic memory signals was analyzed and the relationship between magnetic field values and the cycle at the fixed position was also analyzed.It was found that an inversion phenomenon of the magnetic signal appeared at 150,000 cycles times （about 30% final week cycle times）for the specimen.Comparison was made for the variation of the magnetic signal characteristic parameters K max and the material damage parameter D in damage mechanics model and it was found that the parameter D could be expressed by the K max ,which might provide a means for using the metal magnetic memory testing technique to evaluate the extent of material damages.