SU1194892A1 - Method of producing high-strength cast iron - Google Patents

Abstract

A method for producing high-strength iron, including laying the bottom of a ladle with a magnesium-containing master alloy, coating it with an iron-containing protective layer and pouring the molten iron into a ladle, characterized in that, in order to increase magnesium absorption, eliminate the pyroeffect, reduce the energy losses, The protective coating is cooled to 243-263 K before entering the ladle and is introduced into the ladle in an amount of 0.02-0.04 by weight of the cast iron.

Description

FIELD OF THE INVENTION The invention relates to foundry, in particular, to the production of high-strength nodular cast iron.

The aim of the invention is to increase the degree of absorption of magnesium, eliminate the pyroelectric effect, reduce energy losses and improve the mechanical properties of castings.

The goal is achieved by the fact that the protective coating applied to the magnesium-containing ligature in the amount of 0.02-0.04 by weight of the metal is cooled to 243-263 K before entering the ladle.

As a result of the formation of a stable coating on the surface of the modifier, consisting of an iron-containing coating and crystallized on its surface and in the pore space of cast iron, cooled on the surface of the iron-containing coating to a crystallization temperature due to additional heat losses on its surface, it eliminates the two-stage treatment of cast iron, reduce energy losses, improve the efficiency of modification, the degree of absorption of magnesium, eliminate the pyroelectric effect due to the reaction bias and a modifier with liquid iron by the time the ladle is filled with melt to the required level. I

The duration of the displacement of the start of the reaction is determined by the following processes: freezing the iron crust on the supercooled coating, overheating the resulting coating crust to evaporating temperatures and dissolving the modifier. During this time, the molten iron manages to fill the ladle to such a level that the metal-static pressure created by it will cause the ligature to interact with the iron in the volume of the molten iron, i.e. under non-oxidizing conditions, which ensures a high degree of magnesium assimilation, interaction without pyroelectric effect and high process stability. If the cooling temperature of the protective coating is greater than 263 K, then the protective layer is heated, the iron interacts with the ligature. It begins earlier than the necessary amount of metal is accumulated in the ladle, resulting in an incomplete use of the spheroidizing effect of the ligature due to its floating on the surface of the iron. and burn it with a significant pyro effect.

If the cooling temperature of the coolant coating is less than 243 -K, then the modification process is lengthened due to the longer heating time of the protective coating layer and the ligature to the interaction temperature.

If the protective coating will be less than 0.02 by weight of the metal, the effect of the effect of the cooled protective coating will be practically absent due to the insufficient heat content of the coating.

If the protective coating on the mass is greater than 0.04 by weight of the metal, there will be a place to increase the duration of the modification process due to a longer warm-up time of the protective layer and the ligature to temperature;

Example. Whether cast iron melted in an ICT-6 induction furnace.

Cast iron melt composition,% by mass: carbon 3.35-3.40; silicon. 1.71, 8; manganese 0.25-0.30; phosphorus 0.07-0.08; sulfur 0.03-0.04, overheated to 1420-1430 ° C.

Spheroidizing modification was carried out in a 1.5-ton bucket, preheated to 700-800 ° C. BKM-2 ligature (TU 14-5-37-74) was used as a spheroidizing modifier. The protective iron-containing material (shot of Dec 05 GOST 11964-66) was cooled in a refrigerating chamber to a temperature of 243-263 K. When modifying according to the proposed method, the modifier in the amount of 1.3 1.7% by weight of metal was placed on the bottom of the ladle and covered its pre-cooled iron coating. Treated cast iron at t370-1390 ° C was poured into molds to produce cast standard specimens (wedge specimen). In the course of modifying by a known method, 1.5-2.0% of the modifier was placed on the bottom of the bucket and two-stage casting of cast iron was carried out in the bucket.

The results of an experimental testing of methods for producing high-strength cast irons are given in the table.

The proposed method of obtaining high-strength cast iron in comparison with the known method allows an increase in the degree of absorption of magnesium by 1113%, to exclude the pyro effect ,. reduce energy losses in the modification of 7-10 kW / h, at the same time increase the strength of iron by 9-13%, ductility by 11-14%. The expected economic effect is 5.27, 6 rubles. on 1 ton of suitable castings from VChGG.

Ligature consumption by mass of molten iron,% 1.5 1.7 2.0 1.3 1.3 1.5 Temperatur-. cooling of iron-containing protective coating,. 263 250 Mass of protective iron-containing coating,% by mass of liquid, 01 0.02 of cast iron Residual in iron of magnesium,% 0.038 0.046 0.050 0.035 0.052 Magnesium uptake rate,% 42 42 36 58 58 Energy loss during the modification of iron,. 58.0, 14.0 TB, 0 TB, 0 TT, 0 TT, 2 Presence of pyroelectric effect and SMOKE- No No Yes Yes No No, 1.7 1.3 1.5 1.7 1.7 1.7 263 243,250 263 263 268 0.02 0.04 0.04 0.04 0.05 -0.04 0.054 0.045 0.052 0.053 0.032 0.021 53 58 58 52 31 21 40.0 40.0 TT, T 11.3 lT, 3 TT, T T5,2 That, 9 No No No No No There Is a Way Method Parameters

Famous

pp 1 I 2 1 3 Physical and mechanical properties of cast iron after modifying strength, 590 575 546 620 640 d,, Sha Plasticity iff 2.5 3.0 4.5 5.4 5.1 Hardness, 229 229 207 217 HB 235

Proposed

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11,19448926 high-strength cast iron production. Continuation of table 54 637 645 668 486 270, 95 5.7 5.6 5.4 3.4 1.2 229 210 217 221 207 235

Claims (1)

METHOD FOR PRODUCING HIGH-STRENGTH IRON, including laying on the bottom of the bucket a magnesium-containing ligature, coating it with an iron-containing protective layer and pouring the molten iron into the ladle, characterized in that, in order to increase the degree of absorption of magnesium, eliminate pyroeffect, reduce energy losses and increase the mechanical properties of castings the protective coating before cooling into the bucket is cooled to 243-263 K and introduced into the bucket in an amount of 0.02-0.04 by weight of cast iron. > 1 · 1194892