Phase transformations in exothermal inserts made from self-hardening liquid mixtures on interaction with a liquid metal

Abstract

The use of inserts made from self-hardening liquid mixtures (SLM), which make it possible to mechanize the process of lining the top part of a mold, reduces the head cutting waste of high-quality electric steel to 11-12% [i]. A further decrease in the head waste can be achieved by using exothermal inserts made from SLM. These exothermal inserts are of particular interest.In order to evaluate their behavior during metal casting, we prepared experimental tiles Of trapezoidal shape of the following dimensions: lower base, 95; upper, 60; height 65, and depth i0 mm. The composition of the tiles was 80% sand, 6% ferrochrome slag, 8% iron ore, and 6% exothermal component.To 100% of the batch, we added 7% bonding material in the form of sodium silicate water glass with a density of 1.4 g/cm 3.For the exothermal component we used aluminum (5%) plus 1% NaCI (composition No. i); FeSi iron silicide (composition No. 2); or SiCa calcium silicide (composition No. 3). The tiles were prepared by casting.To evaluate the resistance of the tiles to abrasive wear, we determined their crumbling tendency, which is characterized by the weight loss from the surface layer of a specimen per unit time when the specimen is rolled around the wall of a meshed drum rotating at a frequency of 60 rpm. The properties of the tiles are given in Table i.Tool (U7A) and bearing (ShKhlS) steels were melted in a 50-kg induction furnace and cast in square molds with the head adapters lined with the experimental tiles. The clear surface of the metal was warmed with a graphite sol. The ingots were removed and cut open on an electrochemical-mechanical machine tool along the axis of the longitudinal section.