Research On Application Of Barkhausen In Detecting 18Cr2Ni4WA Steel Internal Stress

Internal stress detection is key to the component’s safety and reliability. Normal internal stress detection methods will destruct the component, and cannot be carried out rapidly in a mass scale. In this paper, based on the theory of Barkhausen effect, a system composed of integrated excitation source, signal sampling and signal analysis is developed on 18Cr2Ni4 WA drawing steel. Property of Barkhausen noise is extracted and hence get the distribution of internal stress.This system is composed of U-shaped Mn-Zn ferrite Magnetizer, H-shaped Mn-Zn ferrite detection coil, LM3886 steel Magnetizer driver, AD620 preamplifier, OP37 active power filter, PicoTech 3206 B digital oscilloscopes, and Micro-Manager platform as capture card driver. The sampled signal is monitored, analyzed, and evaluated by plug-in program by Icy.Experiment and analysis found that the optimal detection frequency for 18Cr2Ni4 WA steel is 35 Hz, and optimal voltage is 12 V. Triangle wave is found to be the best incentive source by analyzing the degree of dispersion and the relationship between Eigen value and internal stress.Analysis and comparison of the stress-strain finite element analysis result between stretched and non-stretched 18Cr2Ni4 WA steel found out that Barkhausen signal is more obvious in residual stress region than non-residual-stress region. In elastic deformation region, Barkhausen signal attenuate as residual stress decrease. There is residual force in elastic-plastic deformation region and uneven plastic deformation region. Barkhausen signal is obvious in this region and has peak point. Double peak in Barkhausen signal indicates this region is of uneven plastic deformation, or the cross section of elastic deformation and plastic deformation. The Barkhausen signal reaches its peak value in the cross section. There is no residual stress in uniformed plastic deformation region after unloaded. In this region, Barkhausen signal will decrease as residual stress increases.This work laid the foundation for measurement and evaluation of 18Cr2Ni4 WA steel gear residual stress.