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Spheroidal Cast Iron for Works at Low Temperature - Requirements, Structure, Properties, Control of the Production Process

Zych Jerzy, Jurga T., Mocek Jan, Myszka Marcin, Snopkiewicz Tomasz

Archives of Metallurgy and Materials

2022

Vol. 67, iss. 3

999--1005

Two standardised grades of spheroidal cast iron determined in standard EN PN 1563-1997 as: EN-GJS-350-22LT (T=-40°C) and EN GJS 400-18LT (T=-20°C) are intended for work at low temperatures: -20 and -40°C. The main mechanical property of these cast iron grades is a high impact strength at a work temperature down to: -40°C. A series of controlled melts was performed to optimise the production technology of spheroidal cast iron, which in as-cast state is characterised by ferritic matrix (the best without any pearlite), fine precipitates of nodular graphite and high purity (without non-metallic inclusions). Variable structures of metal charges and various spheroidisation techniques (the modification methods) (slender ladle with a tight cover - Tundish technology as well as the technology with cored wire) were applied in the research. In order to obtain refinement of graphite precipitates and to achieve the ferritic matrix multistage inoculations of technologies were applied. Cast iron was subjected to refining to limit non-metallic inclusions since they decrease the impact strength. The production process of cast iron was controlled by the thermal derivative analysis at the stage of initial cast iron and after its secondary metallurgy (modification and inoculation). It was pointed out, that the reproducible production of cast iron for work at low temperatures was only possible when all elements of the technological process were strictly adhered to. It was pointed out, in the hereby paper, that: it should be strived to maintain Si content not higher than 2.50÷2.60%, which at producing spheroidal cast iron is sometimes difficult and requires using a lot of pig iron in the metal charge. For a fast assessment of the cast iron quality, concerning its impact strength, the proposed - in the hereby paper - index quality (IQu) can be applied. It is determined on the bases of measuring the cast iron hardness and propagation velocity of ultrasound wave.

The influence of selected elements on mechanical properties of ferritic ductile iron

Soiński M. S., Derda A.

Archives of Foundry Engineering

2008

Vol. 8, iss. 1 spec.

303--308

An attempt of determining the relationship between changes of quantities of elements in the alloy (such as C, Si, Mn, P, S, Cr, Ni, Cu, Mg) and the basic mechanical properties of the material (Rm, Rp,0,2. A5, HB, KCV) has been undertaken on the basis of data concerning production of ferritic ductile iron of the EN-GJS-400-18U-LT grade (according to PN-EN 1563 Standard) from about 300 heats. The examined cast iron has been produced by one of the domestic foundries in the induction furnace of medium frequency, spheroidized by the plunging method and then modified by the in-stream method while transferring the cast iron from the treatment vessel to the pouring ladle. Castings have been heat treated in order to achieve the fully ferritic structure. The analysis of the collected data has shown that even small changes in content of a series of elements (falling within the limits required for production of the ductile iron) can lead to the statistically significant increases or decreases in mechanical properties of ferritic ductile iron.