High chromium cast iron rolls combine high surface hardness with strong wear resistance. They provide excellent stability in demanding rolling conditions and remain one of the most widely used materials for hot rolling applications.
High Chromium Cast Iron Rolls are composite cast rolls produced by a centrifugal casting process. The outer working layer is made of white cast iron containing 12%–22% chromium, offering excellent wear resistance. The roll neck and core are made of high-strength nodular cast iron or high-toughness gray cast iron, ensuring both durability and toughness. This combination provides superior performance in resisting abrasion and thermal fatigue during rolling operations.
High chromium cast iron rolls feature an outer layer rich in chromium, giving them a hard and wear-resistant structure. After heat treatment, the roll surface develops a refined microstructure mainly composed of tempered sorbite, with small amounts of martensite, retained austenite, and hard carbides.
With a higher Cr/C ratio, the carbides change from M₃C to M₇C₃ and M₂₃C₆ types, among which M₇C₃ offers superior hardness and wear resistance. For composite rolls, a nodular cast iron core is often used, featuring a structure of pearlite, ferrite, minor carbides, and spheroidal graphite, providing excellent toughness and resistance to thermal fatigue.
Based on the above microstructural features, high chromium cast iron rolls exhibit excellent comprehensive performance. The predominant M₇C₃ carbides provide high microhardness and outstanding wear resistance. During operation, a dense and adherent Cr₂O₃ oxide film forms on the roll surface, which not only protects the matrix but also further enhances wear resistance. The core, made of high-strength nodular cast iron, is carefully controlled to consist of pearlite, bull’s-eye ferrite, minor carbides, and spheroidal graphite, ensuring excellent fracture resistance. The outer layer is of a white iron structure with nearly uniform hardness throughout the working zone. However, due to the high carbide content in the matrix, thermal conductivity is relatively low and sensitivity to thermal shock is high, so effective water cooling is essential during service to maintain stable performance and long service life.
High chromium cast iron rolls are generally produced by the centrifugal casting method rather than the full pouring method, as the high chromium content in the outer layer makes it difficult to ensure sound internal properties when fully poured. Horizontal, vertical, and inclined centrifugal casting techniques are all applicable for producing these rolls. The core typically uses nodular cast iron, which provides higher strength and better load-bearing capacity than gray cast iron.
High chromium cast iron rolls perform reliably in a wide range of hot rolling operations, including:
They deliver long service life, stable rolling performance, and outstanding resistance to wear and thermal stress.
Copyrights © 2025 sc-rolls. All rights reserved.
扫一扫加微信
