Microstructure-property relationships in high chromium white iron alloys

TLDR

High‑chromium white irons are ferrous alloys (11–30 wt % Cr, 1.8–3.6 wt % C, with optional Mo, Mn, Cu, Ni) whose microstructure—hard primary/eutectic carbides in an austenite matrix—provides excellent abrasion resistance for mining and mineral‑processing applications, and whose properties are strongly influenced by alloy composition, solidification, and thermal processing. The review aims to outline how solidification and thermal processing develop the microstructure of high‑chromium white irons. The review discusses conventional processing effects and advances in alloying and cryogenic treatments that influence microstructure. Laboratory abrasion tests show that microstructure governs wear properties, while toughness and impact resistance are reviewed in relation to microstructural constituents.

Abstract

AbstractAbstractHigh chromium white irons are ferrous based alloys containing 11–30 wt-% chromium and 1.8–3.6 wt-% carbon, with molybdenum, manganese, copper, and nickel sometimes added as additional alloying elements. The microstructure of these alloys typically consists of hard primary and/or eutectic carbides in a matrix of austenite or one of its transformation products. The presence of hard alloy carbides results in excellent abrasion resistance and, consequently, these alloys are commonly used for materials handling in the mining and minerals processing industries. Alloy content, solidification parameters, and thermal processing can dramatically alter the microstructure that is produced, and this in turn can influence the properties and hence performance of white iron alloys during service. This review outlines the development of the microstructure in high chromium white irons through solidification and thermal processing. The metallurgical effects of conventional processing techniques are discussed, and advances in aspects such as alloying and cryogenic treatments covered. The results of laboratory abrasion tests are summarised, and the effect of microstructure on the wear properties are discussed. The toughness and impact resistance of white cast irons, which are often thought to represent a limiting factor in their use, is reviewed, with particular regard given to the effects of microstructural constituents.