Measurement of the residual stress distribution of SUS316L stainless steel using an eddy current method

To improve the fatigue strength and resistance to stress corrosion cracking, peening is the effective technique because of the introduction of compressive residual stress. As penetration depth can varies with frequency and electromagnetic properties are varied with the induced stress, an electromagnetic method is proper to evaluate the peening efficiency nondestructively. The piezoresistive effect and Villari effect cause the variation of electromagnetic properties like as the electrical resistivity with the introduction of stress. It was reported that the electromagnetic properties were varied with processing time of peening and depth where the compressive residual stress was introduced. In this paper, to establish the evaluating method of peening intensity and homogeneity after peening, austenitic stainless steel, Japanese Industrial Standards (JIS) SUS316L treated by cavitation peening which causes little variation of surface roughness and microstructure were evaluated by means of an eddy current method with coil scanning. In results, the peening intensity can be evaluated by the eddy current method.