ASSESSMENT OF CHEMICAL COMPOSITION AND PROPERTIES OF CAST IRON WITH NODULAR GRAPHITE FOR CASTINGS (PROBABILISTIC APPROACH)

Procesi littâ, 2024, Vol 3 (157), 36-45

Abstract

High-strength cast iron with nodular graphite is a material whose application is constantly increasing in mechanical engineering and other industries. The chemical composition and mechanical properties of castings made of high-strength nodular cast iron of different grades, which are produced in accordance with the requirements of DSTU 3925-99, are analysed. The methodology for calculating the carbon equivalent and the degree of eutecticity of cast iron using the probabilistic approach and the Monte Carlo method has been refined. It is shown that the nature of the distribution of chemical element content values in their ranges does not affect the average values of carbon equivalent and eutecticity of high-strength cast iron with nodular graphite. Based on the data on the recommended chemical composition of high-strength cast iron with nodular graphite of various grades, presented in DSTU 3925-99, the values of carbon equivalent and degree of eutecticity were calculated using the Monte Carlo method, assuming that the distributions of the values of the content of chemical elements in accordance with their ranges defined by the standard in the composition of cast iron are subject to a normal Gaussian law or uniform distribution. It has been established that the values of carbon equivalent and degree of eutecticity of the chemical composition of high- strength cast iron with nodular graphite recommended in DSTU 3925-99 vary little in cast irons of different grades. The carbon equivalent ranges from a minimum value of 3.2986% to a maximum of 4.5756%. The degree of eutecticity ranges from 0.7480 to 1.1040. The distribution law of the chemical element content in cast iron (normal or uniform) has almost no effect on the average values of these indicators. The mean square deviations are approximately three times smaller in the case of using a uniform distribution of chemical element content values in their ranges in the cast iron composition. The dependence of strength and hardness of high-strength cast iron with nodular graphite on the carbon equivalent and the degree of eutecticity, calculated according to the chemical composition of such cast iron recommended by DSTU 3925-99, does not appear.