Analysis of Carbides in Multi-component White Cast Iron for Hot Rolling Mill Rolls

• Published in: ISIJ International Vol. 44; no. 2; pp. 372 - 380
• Main Authors: Hashimoto, Mitsuo, Kubo, Osamu, Matsubara, Yasuhiro
• Format: Journal Article
• Language: English
• Published: Tokyo The Iron and Steel Institute of Japan 01.01.2004; Iron and Steel Institute of Japan
• Subjects: alloyed carbide; carbide reaction; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Precipitation; rolling mill roll; Solid-phase precipitation; white cast iron; Crystal growth; Hot rolling mill; Scanning electron microscopy; Alloy cast iron; Electron diffraction; XRD; Experimental study; Dispersive spectrometry; Precipitates; Solidification; Precipitation; Transmission electron microscopy; Rolling mill roll; Microstructure; Carbides; White cast iron; Crystal structure
• ISSN: 0915-1559; 1347-5460
• DOI: 10.2355/isijinternational.44.372

A multi-component white cast iron was developed for rolling mill rolls. The morphology and alloy concentration of carbides precipitated during solidification were investigated using X-ray diffraction, SEM, TEM and EDS analysis in the cast iron with typical chemical composition of Fe-2%C-5%Cr-5%V-5%Mo-5%W-5%Co (mass%). When the iron solidifies, petal-like MC carbides with face-centered cubic lattices and plate-like M2C carbides with hexagonal lattices crystallize. During heat treatment, M2C carbide (hexagonal) reacts to γ-Fe and transforms to M6C (fcc), M7C3 (orthorhombic) and MC (fcc) carbides, but the reaction is not followed by a change of carbide morphology. MC carbides mainly consist of V, and M7C3 carbides are mainly formed by Cr and Fe. M2C carbides contain 20-25 atomic% each of Cr, V, Mo, and Fe, and 12 atomic% of W. M6C carbides are composed of approximately 33 atomic% of (Mo+W), and 50 atomic% of Fe and (Cr+V) in the balance.