The Squid Combination Of Eddy Current Method For Residual Stress Detection Of Beryllium Feasibility Study

Non-ferrous metal Beryllium was widely used in many fields for its special characters,Due to its brittleness, the beryllium components might be damaged by the residual stresscaused during machining and welding. Accordingly, itis important to examine the statusof residual stress in Be components. While industrial CT, XRD(X-Ray Diffraction) andBarkhausen methods failed to accomplish, it was needed to find a new way.Eddy Current was a NDE(Non-Destructive Evaluation) method based on testingthe changes of electromagnetic property. And,SQUID(Superconducting QUantum Inter-ference Device) has been extended to NDE since 1980s. Different from the conventionalelectromagnetical detecting method, the magnetic flux density B was directly examined bySQUID. Besides, SQUID has some other better capabilities: a wider operating frequencybandwidth, from dc to MHz, and higher sensitivity.In this paper, A method based on SMM-601 by Tristan Company was developed tomodel SQUID. The magnetic flux change in the SQUID detection coil was calculated byFinite Element Method. The dependence of residual stress on magnetic flux was com-puted. In addition, the interval effect and temperature alteration effect were discussed.What's more, the ways to restrain the foregoing two side effects were listed and takeninto account.According to the computed results: the dependence of axial residual stress on mag-netic flux of SQUID was 1.194×10^-16Wb/MPa, and the radius of SQUID in our modelwas 1.728mm. While the sensitivity of SQUID was 10^-20Wb/Hz^1/2·mm². Therefore thischange of residual stress was measurable by SQUID. In addition, the magnetic flux changeis nearly in linear with residual stress intension.In a word, a new method based on SQUID and eddy current to examine residualstress in beryllium components was feasible. While there were still much difficulty on theway to be realized. A thorough research is needed.