Improved Color Metallography for a Low Alloy Hardened White Cast Iron

摘要

In this experimental work, several single and double chemical color etching techniques have been developed to identify in details the as cast optical microstructural observation in a low alloy as cast hardening white iron. The etching techniques are based on the various metallographic reagents involving 2%nital, Marshall's, Glyceregia, 5%ammonium persulfate, Kalling's N0.1 and aqueous ferric chloride chemical solutions. Evidence is presented which indicates that the microstructural components including retained austenite, martensite, pearlite, secondary and M3C eutectic carbides can be distinguishable colorful from each other in the multiphase white cast iron microstructure. The results indicate that the retained austenite has been appeared in a good contrasting resolution by different colors such as brilliant green and brilliant white after using double etching procedures consisting of Marshall's followed by Kalling's N0.1 and Marshall's with the subsequent use of 5%ammonium persulfate respectively, while the martensite is stained by lightly brown color after using these associated double metallographies. The martensite has been also colored by sharply contrasted brilliant brown after using a single etching technique of 5%ammonium persulfate. The secondary carbide has been stained in a good contrasting observation as dark and bright particles with double etching techniques based on the Marshall's followed by Glyceregia and Marshall's with aqueous ferric chloride solutions, respectively. The X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) micrographs are confirmed the as cast optical microstructural evolution developed in the low alloy white iron.