Accurately determining retained austenite levels in low-carbon TRIP steel sheet through saturation magnetization measurement

In this paper, saturation magnetization measurement was successfully applied to evaluate the volume fraction of metastable retained austenite ( gamma sub R ) in low-carbon TRIP aided multi-phase steel sheet. The gamma sub R of this steel becomes unstable at the surface due to a lack of lattice constraint. The X-ray method, conventional method, proved to evaluate the volume fraction at the surface. On the other hand, saturation magnetization proved to be comparatively an accurate method due to the inherent bulkiness of the gamma sub R .