30CrMnSiNi2A钢疲劳损伤二维磁记忆检测的试验研究

Experimental Study of 30CrMnSiNi2A with Fatigue Damage Based on Two-dimensional Magnetic Memory Testing

选取不同厚度30CrMnSiNi2A平板缺口试样在0.7σs应力水平下进行低周疲劳试验,并实施磁记忆二维检测,研究不同厚度、不同循环周次下的磁记忆信号变化规律。研究结果表明:随着循环次数的增加,局部应力集中部位的磁记忆信号特征越来越明显,信号幅值也越来越大,并在裂纹失稳断裂前出现明显的法向分量过零而切向分量具有最大值的特征;法向分量和切向分量微分后合成的李萨如图形的封闭区域大小随循环周次呈现Logistic曲线变化,可定量分析构件疲劳损伤程度。该研究结果可为进一步进行磁记忆二维检测研究提供技术支撑。

The experiment selects different thickness of the 30CrMnSiNi2A flat notched specimens, which experiment with low cycle fatigue testing under the stress of 0.7 σ, level, and conducts a two-dimensional magnetic memory testing, researehs the variation of magnetic memory signal under different cycles and different thickness. The experimental results show that： with the increase of the number of cycles, the characteristics of the magnetic memory signal of local stress concentration become more and more obvious, and the signal amplitude is also growing, the most significant characteristic phenomenon appears before the unstable crack fracture, which the normal component exists zero point, while the tangent component has max. The Logistic curve of the equivalent area of the closed field of the Lissajous synthesized by the differential of the normal and tangent component with cycles was fitting, it can be used to quantitative analysis the degree of fatigue damage. These results will provide technical support for further research on 2D testing of magnetic memory.