High-strength and high-tenacity nodular cast iron and working roll of wide thick plate

Abstract

The invention relates to the improvement of nodular cast iron, which is characterized in that 3.0-3.5 wt% of C, 2.0-2.8 wt% of Si, 0.5-0.8 wt% of Mn, not more than 0.08 wt% of P, not more than 0.02 wt% of S, 0.5-1.2 wt% of Cu, 0.2-0.6 wt% of Mo, 0.05-0.1 wt% of Mg, 0.01-0.03 wt% of Ca, 0.01-0.015 wt% of Re, 0.001-0.003 wt% of Sb, 0.01-0.05 wt% of Ba and the balance of Fe and impurity elements are smelted, then added into yttrium-based heavy rare earth magnesium for nodulizing by using a pour-over process; after nodulizing, a long-acting yttrium-based inoculant and silicon iron are utilized to carry out compound inoculation. The obtained nodular cast iron has both high strength and high tenacity, wherein the tensile strength of as-cast nodular cast iron is not less than 500MPa, and the tenacity is not less than 9J/cm2; by metallographic analysis, the as-cast nodular cast iron has a structure with part of fine pearlites and globular graphite, and the graphite globuring ratio can be improved by more than 2 levels. The invention is especially suitable for the high-strength nodular cast iron used for the core of the working roll of a wide thick plate, thereby greatly prolonging the service life of the working roll.

Description

technical field [0001] The invention relates to the improvement of nodular cast iron, in particular to a nodular cast iron with high tensile strength and excellent toughness, and a hot-rolled wide and thick plate work roll. Background technique [0002] The hot-rolled work rolls for wide and thick plates (such as thickness ≥ 50mm, plate width ≥ 3.5m) are usually composed of a high wear-resistant iron-based material outer layer and a ductile iron core, which are composited by centrifugal casting. The material for the core of the work roll generally adopts the national standard grade SG I, SG II or SGIII chrome-molybdenum nodular graphite infinite chilled cast iron. The original molten iron of the above three materials is spheroidized by adding magnesium under pressure or light rare earth magnesium. Single ferrosilicon (such as FeSi75Al10.5-A) after inoculation, as a material for the core of centrifugal composite wide and thick plate work rolls, such as chemical composition (w...

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Problems solved by technology

However, due to the high content of phosphorus in the core, the phosphorus eutectic is easily precipitated at the grain boundary, which affects the bonding strength of the grain boundary, aff

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