Influence of Work-Induced Martensite Transformation by Shot Peening Content on Eddy Current Reaction

Author:  Yoshiyasu Makino, Nobukazu Kondo, Hideaki Kaga
Source:  ICSP-13
Doc ID:  2017050
Year of Publication:  2017
Introduction: Shot peening (referred to as SP), which improves fuel efficiency by making product parts lightweight and high-strength, is used in the aerospace and automobile industries. [1]SP is one type of surface modification method, and many studies have shown that the compressive residual stress distribution induced by SP greatly contributes to fatigue strength improvement. [2]-[4] Therefore, it has become important to measure compressive residual stress. X-ray residual stress analysis is generally used for steel, but X-ray permeation depth is several μm from most surfaces, and the only option is to scrape it in electro-polish to measure the depth distribution of stress. Therefore, it is performed only through a sampling check. A quick and nondestructive method to check the residual stress depth distribution introduced by SP is needed. [5] Electromagnetic methods such as eddy current measurement can evaluate in principle the stress in SP processed steel caused by the reverse magnetostriction effect that changes magnetic properties when elastic strain or plastic strain is introduced to the ferromagnetic material by the skin effect of eddy currents.

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