镍铜合金棒材裂纹的弱磁检测

摘要

针对现有无损检测技术难以满足镍铜合金棒材裂纹检测需求的现状,提出一种地磁场环境下的弱磁无损检测方法.首先理论分析镍铜合金棒材的弱磁检测原理和缺陷处磁异常分布特征,其次对含自然缺陷的镍铜棒材进行弱磁检测.采用包络分析法对信号进行处理,并通过金相显微镜、扫描电镜分析,验证弱磁检测镍铜合金棒材的可行性.结果表明:通过对棒材表面磁异常分布特征分析,并结合磁梯度信号的阈值处理和包络分析法处理的结果,实现了镍铜合金棒材内部裂纹缺陷的有效检出,并且裂纹检测精度达到了微米级.%Aiming at the present situation that the existing nondestructive testing technology can not meet the requirement of crack detection of nickel-copper alloy bar,a weak-magnetic nondestructive testing method in the geomagnetic field is proposed.In this paper,the theory of weak magnetic detection of nickel-copper alloy bars and the distribution of magnetic anomalies at defects are firstly analyzed,and then the weak-magnetic testing was carried out on the Ni-Cu alloy bar with natural defects.The envelope analysis method was used to process the signals,and the feasibility of the weak magnetic detection of nickel-copper alloy bars was verified by metallographic microscope and scanning electron microscopy.The results show that the effective detection of cracks in Ni-Cu alloy bar is achieved by analyzing the distribution of magnetic anomalies on the surface of bar and combining with the results of threshold processing and envelope analysis of magnetic gradient signals, and the precision of crack detection can achieve micron-level.