SU1680790A1 - Method of treating hot metal - Google Patents

Abstract

The invention relates to metallurgy, specifically to foundry, in particular to the processing of pig iron. The purpose of the invention is to improve the mechanical properties of cast iron. The proposed method includes the release of iron into a transfer bucket with a ligature containing REM preliminarily placed on its bottom, the introduction of graphite, blowing with neutral gas, overflowing into a pouring bucket and treating the iron in a stream of neutral gas with a mixture of activated ligature FSZORZM20 and graphite with a specific surface of 20-25 m2 / g, and the amount of rare-earth metals and graphite is chosen from the ratio of rare-earth metals: graphite 1: 1 - 20. With the development of the specific surface to the specified value (20-25 m2 / g), the reactivity of ligature modifiers and g Afit that enhances the absorption of the input with a ligature and REM improve graphite modifying effect. 1 tab. l With

Description

The invention relates to metallurgy, more specifically to the foundry industry, in particular to a method for processing iron.

The purpose of the invention is to increase the mechanical properties of cast iron.

According to the proposed method of processing iron, including the production of molten iron in a transfer ladle with a ligature containing rare earth elements (REM) previously placed on its bottom, the introduction of graphite and blowing with neutral gas, pouring over the casting ladle, the iron is further treated in a pouring ladle in a jet of neutral gas a mixture of activated ligature FSZORZM20 and graphite with a specific surface

20-25 m / g, the amount of rare-earth metals and graphite is chosen in the ratio of rare-earth metals: graphite 1: 1 -20.

The essence of the invention is

sequential processing of cast iron with mechanically activated additives, in the result of which 0.03-0.05% of rare-earth metals and 0.05-0.9% of graphite are added to the melt.

Mechanical activation of the FSZORZM20 ligature and black graphite is carried out in differential-centrifugal, planetary, centrifugal mills, disintegrators, etc. when the material is subjected to a load of 100–150 g (g is the gravitational constant) until the specific surface reaches 20–25 m / g. With

00

about

x |

specific surface area above or below 20-25 m2 / g, the reactivity of the modifiers decreases.

With the development of a specific surface, the reactivity of modifiers increases, contributing to a more complete assimilation (dissolution) of REM introduced with a ligature and an increase in the modifying effect of black graphite. An increase in the number of graphite nuclei has a significant effect on the properties of cast iron and the rate of graphitization, with graphite itself being a possible nucleus of graphite.

Processing of cast iron in the casting ladle in the amount of 0.2–0.75% with simultaneous bubbling in a jet of neutral gas ensures uniform distribution of graphite throughout the metal, has a graphitizing effect, preventing the crushing of graphite caused by the processing of rare-earth metals, increases the number of embryos graphite with fewer injected graphite. With the introduction of more than 0.75% of graphite is observed, with a decrease in the strength properties of cast iron.

In order to stabilize the modifying effect of graphite in the melt and to improve the structure of cast iron, the mechanically activated ligature of PFSOR20 MW is additionally introduced into the casting ladle in a stream of neutral gas by the proposed method. The introduction of ligatures in the amount of less 0,015%, ineffective.

To test the proposed method of treatment, iron smelted in a cupola, superheated to 1400 ° C, containing,%: C 3.42; Si 2.3; Mp 0.62; S 0.15; P 0.09 is discharged into a transfer bucket, at the bottom of which there is a mixture of the master alloy FSZORZM20 of the following composition,%: REM 20-30; SI30-35; AI 2 - 5; Fe rest.

After holding for 0.5 - 1 min, graphite is introduced into the stream of neutral gas through the immersed form, followed by

bubbling gas. Argon is used as a neutral gas. After that, the cast iron is poured into the casting bucket with a capacity of 150 kg and a mechanically-activated mixture of FSGSM20 and graphite ligature is introduced into the stream of neutral gas through a submerged tuyere. After soaking in a ladle for 1-2 minutes, they are cleared of slag and, at 1350 ° C, poured into clay-clay forms.

The table shows the data obtained from the processing of iron according to the proposed method and the study of the microstructure.

In all cases, a structure was obtained with evenly distributed rather large inclusions of graphite of shortened rectangular shape, which reduces the number of cuts and increases the strength of cast iron. Metallic base - perlite. The best results on the mechanical properties of cast iron were obtained at a ratio of rare-earth metals: graphite 1:10 with a specific surface of 20-25 m2 / g.

Thus, the processing of cast iron in accordance with the proposed method provides a uniform structure over the section of castings and high strength of cast iron.

Claims (1)

Invention Formula A method of treating pig iron, comprising releasing molten iron into a transfer bucket with a ligature containing rare-earth elements previously placed on its bottom, introducing graphite and purging with neutral gas, pouring it into the casting bucket and processing with a ligature, characterized in that, in order to improve the mechanical properties of the cast iron, in the pouring ladle, the treatment is carried out in a stream of neutral gas with a mixture of an activated ligature FSZORZM20 and graphite with a specific surface of 20-25 m2 / g, and the amount of REM and graphite is chosen in a 1: 1 ratio -20. oh oh oh oh oh Cast iron treated with non-activated additives 1 - 1:20 0.04 0.8 GF 1 81:30 0.05 1.5 GF 1 Cast iron, processed by a known method SCH-101: 20 0.03 0.05 GF 1 1:40 0.02 0.15 GF12 1:15 0.01 0.8 GF 1 1:20 0.05 1.0 GF 1 Table continuation 228 213 110 95 BUT 89