Welding residual stress ultrasonic evaluation method based on dynamic magnetostriction coefficient measurement

Abstract

The invention discloses a welding residual stress ultrasonic evaluation method based on dynamic magnetostriction coefficient measurement. The fundamental principle of the welding residual stress ultrasonic evaluation method based on dynamic magnetostriction coefficient measurement is that a magnetostriction coefficient of ferro magnetic material is sensitive to stress; when the stress state of the ferro magnetic material is different, the magnetostriction coefficient curve changes so as to influence the magnetic-acoustic conversion efficiency. By means of measuring different magnetizing field intensity, a transverse wave reflection signal amplitude changing curve received by a magnetic induced shrinkage or elongation transverse wave sensor in a welding area can dynamically reflect the changing rule that the magnetostriction coefficient curve changes following the stress. By means of regulation and control of an electromagnet field current amplitude and a period, multi-time of equiamplitude excitation and reception for a transverse wave signal can be realized and a changing curve, that is a dynamic magnetostriction coefficient curve, that the amplitude of a transverse wave reflection signal changes following the change of a surface tangential magnetic field intensity. A transverse wave amplitude under any surface tangential magnetic field intensity or a gradient parameter of the dynamic magnetostriction coefficient curve can represent the magnitude of the residual stress of a welding area.

Description

Technical field: [0001] The invention belongs to the technical field of stress nondestructive measurement, and relates to an ultrasonic evaluation method of welding residual stress based on dynamic magnetostriction coefficient measurement. This method utilizes the influence of welding residual stress on the magnetostriction coefficient curve of ferromagnetic materials, adopts the magnetostrictive shear wave test method, measures the dynamic magnetostriction coefficient curve of the welding area, and extracts the characteristic parameters for the tensile and compressive residual stress of the welding area. Characterized by size. Background technique: [0002] The welding process is a process in which the weldment is locally heated and then gradually cooled. The uneven temperature field will cause uneven deformation of each part of the weldment, resulting in welding residual stress. The welding residual stress seriously affects the fatigue strength, brittle fracture resistanc...

AI Technical Summary

Problems solved by technology

Since the acoustoelastic effect is relatively weak and the sensitivity of sound velocity to stress is not high, when this method is used for detection, the requirements for signal acquisition hardware are relatively high, and the detection results are susceptible to noise interference

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