Extraction and 3-Dimension Morphology Characterization of Metastable Secondary Phase in Steel

Abstract

Metastable secondary phase in steel mainly includes sulfide inclusions, rare earth inclusions and nano-scale inclusions or precipitates etc. Many researches indicate that these metastable phases have an important effect on the property of steels. Now, people are going to employ metastable secondary phase to improve the property of steel. Metastable secondary phase in steel usually was studied by metallographic technology in many previous researches because they were destroyed easily by acidic or alkaline reagents during separating from steel. Therefore, the 3-dimension morphology could not be observed through electron microscopes. A method to extract metastable secondary phase in steel using electrolysis technology with organic solution electrolyte is introduced in the paper. Several sorts of metastable phase including MnS, Ce2O3, nano TiN et al are extracted nondestructively by electrolysis with organic solution electrolyte in various steel grades. The 3-dimension morphology, the inside cross-section 2-dimension morphology and composition of these metastable phases are analyzed by scanning electronic microscope (SEM), FE-SEM and transmission electron microscope (TEM). Current research results prove that electrolysis with organic solution electrolyte is an accurate and effective method on preparing sample of metastable secondary phase in steel used to electron microscope analysis.