The Influence of Undercooling ΔT on the Structure and Tensile Strength of Grey Cast Iron

Abstract

Inoculation of cast iron has become a commonly used metallurgical process, which is carried out in a foundry in order to improve the mechanical properties of utility alloys. It consists in changing the physicochemical state of the melted alloy. This change is caused by the introduction of cast iron with a low ability to nucleate graphite, shortly before pouring a small mass of the substance—an inoculant that increases the number of active nuclei. It is also justified that the literature often connects an increase in the tensile strength UTS of the inoculated grey cast iron, with changes in the characteristics of the particles of graphite. However, in strongly hypoeutectic cast iron, in which a large number of primary austenite grains crystallize, the interdendritic distribution of graphite is usually the result. It also follows that the nature of the graphite precipitates is determined by the mutual relations between the interfacial distances in eutectic grains and the interdendritic distances in the grains of primary austenite occurring in the Fe–C alloys. The article presents the influence of the inoculant on the characteristics of the precipitation of primary austenite grains in relation to the sulphur content in grey cast iron with flake graphite. The study also showed that primary grains in grey cast iron have a great influence on mechanical properties, such as the tensile strength UTS. In this case, the key is to know the value of the degree of undercooling ΔT. The type of inoculant used affects the ΔT value. The study related the number of N primary austenite grains with the degree of undercooling ΔT and the tensile strength UTS with the number of primary austenite N grains.

Tensile Strength Prediction of Gray Cast Iron for Cylinder Head Based on Microstructure and Machine Learning

“…[1] In general, feature engineering based on experimental experience and theoretical knowledge is a primary method to guide the selection of features in ML models. Referring to the previous studies, the factors affecting the UTS of GCI include the casting process, [29,30] the chemical composition control, [11,31,32] the heat treatment, [33] and so on. Shirai et al [11] used multielement components as input features to predict mechanical properties.…”

The Effect of High Silicon and Molybdenum Content on the Mechanical Properties and Microstructure of Gray Cast Iron

“…In this paper we focus on the influence of increased content of silicon and molybdenum on the functional properties of gray cast iron to prevent the growth of unfavorable primary graphites [6]. As there is no mention of this type of cast iron in the literature, but only the corrosion resistance of high--silicon gray cast iron, the knowledge about SiMo ductile cast iron will serve as theoretical basis.…”

Archives of Foundry Engineering

“…The material used for this type of castings must meet several important conditions. The microstructure in large size castings, shaped during crystallization and cooling, differs significantly from normal size castings, which is associated with such phenomena as element segregation, graphite flotation, a variable proportion of perlite and ferrite, or shrinkage porosity [1,2]. This also applies to steel castings [3][4][5][6][7][8] and other groups of materials such as alloy cast iron [9,10] or castings from the group of large-size structures used, for example, in the power industry.…”