Effect of the cored wire introduction rate on a degree of magnesium absorption during ladle modifying

Abstract

© 2019, "Ore and Metals" Publishing house. All rights reserved. The features of ladle modification of liquid iron with magnesium flux-cored wire for the purpose of spheroidizing graphite inclusions have been considered, which predetermines the increased mechanical characteristics of cast iron (tensile strength, impact strength, high elongation) and transforms this engineering material into the category of highstrength cast irons. The advantages of ladle modification with cored wire over other alternatives for carrying out this technological operation are the ecological purity of the process and the possibility of its automation, eliminating manual operations and increasing the stability of the modifying effect. An important aspect of the latter circumstance due to a large set of factors that determine it, is the degree of absorption of magnesium by liquid iron. Studies of the effect of the introduction rate of flux-cored wire with magnesium into liquid metal on this parameter when processing liquid iron in ladles of various capacities (1.5 and 3 tons) have been carried out. It has been established that at a temperature of liquid iron of 1400 °C, the introduction into it of cored wire with a diameter of 4.5 mm and a wall thickness of 0.3–0.4 mm, filled with milled magnesium MPF1, leads to high degrees of magnesium absorption (0.8–0. 9), if the wire introduction rate is 1.4–1.5 m/s when using the ladle with a capacity of 1.5 t liquid iron and 1.8–2.0 m/s when using the ladle with a capacity of 3 t. In both experiments the time of the flux-cored wire introduction was determined by the fact that the consumption of magnesium per unit mass of liquid iron was the same (1 g/kg). Adequate mathematical models have been obtained in the form of linear dependences of the magnesium absorption degree on the cored wire introduction rate. Doubling the capacity of the ladle with liquid iron resulted in a 23% reduction in the slope. The sensitivity of ladle magnesium modification of liquid iron in relation to the effect of the cored wire introduction rate on the degree of its assimilation becomes of greater importance when carrying out this technological operation in small-capacity ladles.