疲劳载荷作用下激光熔覆试件磁记忆试验研究

Experimental Study of Laser Cladding Specimen Under Fatigue Load by Magnetic Memory Methods

对Q235基体材料激光熔覆Ni基合金试件进行四级应力水平疲劳试验和磁记忆信号检测试验,研究激光熔覆试件在载荷作用下造成的疲劳损伤对磁记忆信号的影响规律以及激光熔覆参数、疲劳载荷对疲劳损伤程度的影响规律。结果显示利用磁记忆信号均值梯度曲线的突变位置可以标明疲劳损伤位置,采用熔覆区域均值梯度突变峰值和所有检测点均值梯度平均值的比值对疲劳损伤程度进行定量评估。疲劳损伤程度定量评估结果及疲劳试验结果均表明激光功率增加、扫描速度降低,都会使疲劳损伤程度增加,疲劳损伤程度和载荷大小具有较强的相关性,载荷越大,熔覆区域的疲劳损伤亦越大。

Magnetic memory signals of laser cladding Ni-based alloy on Q235 substrate were detected and fatigue test under four different fatigue load were carried out to estimate the fatigue damage of laser cladding specimen by metal magnetic memory technology. The effects of fatigue damage caused by different laser cladding parameters and different fatigue load on magnetic memory signals and laser cladding parameters and fatigue load on the fatigue damage degree were investigated. Results show that the fatigue damage location can be predicted according to the mutational characters of average gradient curve. Quantitative assessment was made for fatigue damage degree based on the ratio of the average gradient mutational peak of cladding region and the average of all the testing point average gradient. The results of quantitative assessment of the fatigue damage degree and fatigue test show that increasing laser power, reducing scanning speed, will increase the fatigue damage degree of laser cladding. There was an inherent relationship between the fatigue damage degree and fatigue load, the larger the fatigue load was, the larger the fatigne damage was.