SU709691A1 - Modifier for cast iron with lamellar graphite - Google Patents

Description

I

The invention relates to metallurgy and can be used in the foundry industry.

A modifier for the treatment of cast iron, containing iron oxide in the form of scale and a carbon-containing component, is known, and silicon carbide spam is introduced as a carbon-containing component in the following ratio of components, wt.%:

Silicon carbide slurry 14-25

Iron OxideErest 1

The disadvantage of this modifier is that for the complete passage of the reaction between iron oxide and silicon carbide, a considerable amount of time and high temperature of the metal during its processing (14OO-145O С) are required. Below these temperatures, the modifier becomes ineffective. When silicon carbide interacts with ferrous oxide, sclac is formed with a high silica content and high viscosity, which reduces the iron reduction tagline and the effectiveness of the modifier.

The aim of the invention is to obtain a simple, benign and effective modifier for cast iron with lamellar graphite, ensuring stable production of pearlite pearl class without bleaching, increasing: tensile strength and bending strength, which reduces the processing time of the melt to achieve the effect of modification and its stabilization.

The goal is achieved in that the modifier for cast iron with lamellar graphite, consisting of silicon carbide or its schm and iron scale, additionally contains calcium carbide and hydrofluorite in the following ratio of components, wt.%:

Iron oxide 45-50

Carbie Calcium 1O-15

Fluorspar5-1O

Silicon Carbide or

his slime the rest.

The effect of the modifier is based on the active course of the process of reducing iron from scale by silicon carbide and calcium carbide and the formation of a center of crystallization in a fine form.

The limits of the ratio of iron, silicon carbide and calcium carbide scale in the modifier are taken so that they fully interact without iron oxide, carbide residues

silicon carbide and calcium carbide, wherein the carbide calcium is introduced into the modifier in such an amount that the calcium oxide formed as a result of its interaction with ferrous oxide completely binds silica, which appears as a result of the reduction of iron oxide with silicon carbide. The decomposition of calcium carbide increases the amount of carbon that converts to liquid 4yryHi and forming calcium oxide reduces the viscosity of the slag, which leads to an increase in the degree of iron recovery from scale.

A decrease or increase in the amount of calcium carbide against the indicated limits causes an increase in the viscosity of the slag and a deterioration in the effects of modification. In order to reduce the viscosity of slags and co. Shortening the time of the process of modifying the pig iron at temperatures not exceeding 1370 ° C, fluorspar is introduced into the composition of the mountain.

Reducing the proportion of fluorspar below these limits does not provide optimal viscosity for slags, which leads to a decrease in the degree of iron recovery from the scale and an increase in time to complete the modification process. Increasing the amount of fluorspar above the indicated limits is impractical due to the increase in its consumption and the higher cost of the modifier.

Modifying the cast iron of the composition: C 2.9-3.0%: SI 1.7-1.8%: MP 0.5-0.6%, is carried out in a ladle at 135 ° -136 ° C. The amount of modifier is 1.0% by weight of the molten metal. The modifier is introduced to the bottom of the heated to 700-8OO C bucket.

When the ladle is filled with iron, calcium carbide and silicon carbide actively react with iron oxides in the temperature range of 1100-15OO ° C. The resulting silicon and carbon in the atomic form are transferred into the melt, serve as centers of graphitization, which help to reduce the degree of supercooling of the melt, grinding graphite inclusions and grains of cast metal, obtaining a homogeneous structure in different sections of the casting, increasing the tensile strength during stretching and bending of the cast metal . The modifier is effective at temperatures not exceeding 135 ° -136 ° C. The method of introducing the modifier into the melt is not difficult.

To compare the results obtained in the experiments using the known. modifier .. The results of the experiments are shown in the table. When the cast iron is processed with the modifier described, the tensile and flexural strengths increase by an average of 10%: the melt processing time to achieve the effect of modifying is reduced three times. Formula Modifier for iron with lamellar graphite containing iron scale, silicon carbide or its sludge, which is different in that it also contains calcium carbide and spar in order to increase the tensile strength of the metal in tension and bending and shorten the modification time. in the following ratio of components, weight%: Scale iron 45-5O Calcium carbide Yu-15 Fluorspar 5-10 Silicon carbide or its sludge Else. Sources of information taken into account in the examination 1. USSR author's certificate in application No. 2390870, cl. C 21 C 1 / OO, 1976.

Claims (1)

Claim A modifier for cast iron with lamellar graphite containing iron oxide, silicon carbide or its sludge, characterized in that, in order to increase the tensile strength of the metal under 15 tensile and bending and reduce the modification time, it additionally contains calcium carbide and fluorspar in the following ratio compo nents, wt.%: Dross of iron 45-50 Calcium carbide 10-15 Fluorspar 5-10 Silicon carbide or his slime Rest.