REBELLO, J. M. A. ; CAMERINI, C. G. ; AREIZA, M. C. ; CARNEVAL, R. ; SANTOS, R. W. .
Resumo: Duplex stainless steels (DSS) are two-phase materials whose microstructure consists of grains of ferrite (δ) and austenite (γ). DSS exhibit attractive properties only when δ and γ phases are in equal proportions. For this reason, it is worthwhile, for industrial applications, to have a NDE technique that could reliably determine the δ/γ ratio. The goal of the present work is to develop an eddy current (EC) method to accomplish this task. Four samples were prepared with different ratios of δ/γ Previous works have shown that the conventional EC technique was unable to distinguish different amounts of these phases. In order to inspect the samples, a detailed study of the magnetic behavior using magnetic hysteresis loop measurements of materials with different δ/γ ratios was accomplished, and, it was verified that the different δ/γ ratios become detectable around the magnetic flux density saturation level. The current work cares about DSS inspection using EC methods in the saturation level. Simulations using commercial software were performed to check the capability to saturate the samples using permanent magnets, and a gaussmeter to find the best configurations for the magnets. Experimentally the samples were brought to saturation as previously designed in the simulations and the EC inspection was able to successfully separate samples with different δ/γ ratio.
