Evaluation of Tensile Residual Stress in Welded Steel Plates Using Acoustically Stimulated Electromagnetic Response

Acoustically induced electric and magnetic polarizations and their sensing applications

“…Figure 15 shows the measurement setup and a typical hysteresis curve of the ASEM signal in steel. 39,40) ASEM measurements were performed using a 4 MHz focusing transducer with a delay medium (a 27 mm long polystyrene pillar) to separate the transducer excitation pulse from the ASEM signal. The signal was detected by a resonant loop antenna tuned to 4.1 MHz.…”

“…(d) Typical ASEM hysteresis curve in steel. 39,40) Here,the in-phase component VX (solid line) and the quadrature component VY (dotted line) were obtained by PSD. 39,42) The black, blue, and red lines represent the initial magnetization curve, the downward-field curve, and the upward-field curve, respectively.…”

“…15(d)]. 39,40,42) The coercivity H c and the remanent magnetization signal µ ¢ = ( ) V d H 0 r are determined from the intercepts of the transverse and longitudinal axes in the ( ) V H X hysteresis loop, respectively. The signal voltage V r is the ASEM intensity arising from the remanent magnetization.…”

“…17 and 18). 40) The specimen was partially welded along the center line on one side of the steel plate. Because the welded face contracts after heating, tensile residual stress is expected to be generated on the opposite face (the upper panel in Fig.…”

“…The discrepancy can be explained as being due to plastic deformation, which is supported by the electron backscatter diffraction method. 40) In plastic deformation, the internal stress is released by the rearrangement of crystal grains. Although the plastically deformed region is usually undetected in the HD method, the history of excessive stress applied beyond T Y is firmly recorded by the magnetic parameters even after the internal stress is released.…”