SU1359305A1 - Method of graphitizing treatment of cast iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the manufacture of gray iron castings. The purpose of the invention is to reduce chill. A new method involves treating the melt Fed at its flow rate of 0.005-0.02% by weight of the melt at a temperature of 20-50 ° C above the crucible reaction temperature and the subsequent processing of the melt with ferrosilicate in an amount of 0.05-0.0 2%. Additional melt treatment of FeCI cast iron ensured a reduction in chillings by 1.5-3 times. 1 tab. i (L

Description

The invention relates to metallurgy, in particular to the development of methods for the processing of cast iron.

The purpose of the invention is to reduce attrition.

The essence of the proposed method consists in overheating the melt by 20-50 ° C above the equilibrium temperature of the crucible reaction and additional processing of the melt with ferrocerium in an amount of 0.005-0.02% by weight of the melt.

When a rare-earth metal is introduced into the melt, it is maximally cloudy with microparticles, which are further activated by ferrosilicone barium and are activated by graphitizing their surface with excess carbon-containing phases from the silicon-containing zones formed by dissolving the silicon-containing additive.

These costs of rare-earth metals (0.005-0.02%) ensure a sufficient degree of melt modification. The lower limit is set, based on the need to achieve a certain degree of melt turbidity with non-metallic inclusions. Exceeding the upper limit (above 0.02%) is not very effective, and the graphitizing affect during the subsequent introduction of ferrosylobacarium remains almost at the same level.

The consumption of ferrosilicobarium (barium content 5–20%) is determined depending on the hardness of the original iron, t, e. depending on the carbon equivalent and the amount of carbide-forming and carbide-stabilizing elements. For alloys whose composition is close to the eutectic flow rate is set at the lower limit. Hypoeutectic cast irons doped with vanadium and chromium require increased consumption of ferrosilicobar. The lower limit of the raykhod (0.05%) makes it possible to sufficiently graphitize soft cast iron (the sum of

chromium, vanadium, manganese less than 0.5%, 50 height 50 mm, the upper part

carbon1 equivalent of 4.3%). Exceeding the upper consumption limit, even when machining cast irons, does not significantly increase the magnitude of the graphitizing effect.

Overheating of the melt by 20–50 ° C above the equilibrium temperature of the crucible reaction before entering the REM removes 10 mm and the lower part 1 mm.

The costs of the tested modifying additives and the results of the comparative tests are tabulated. 55 As follows from the table, additional processing of the molten iron when it is overheated by 20-50 ° C is higher than the crucible reaction temperature at the consumption of ferroceris.

a significant hereditary effect of the quality of charge materials on the properties of castings. When the melt is overheated above the equilibrium temperature of the crucible reaction, silicon is reduced from the oxides, and the oxygen activity in the melt increases. Overheating of the melt is lower than 20 ° С

causes an insufficient rate of the reactions described. Exceeding the upper limit of overheating leads to excessive carbon loss, excessive energy consumption.

5 and does not increase the result of the subsequent graphitizing treatment. Introducing ferrosilicobarium into the melt at a temperature below the equilibrium temperature of the crucible reaction extends the life of the graphitizing effect.

Example. To carry out comparative tests of graphing processing methods, cast iron was used with a hard composition (C 3.25 3.3%; Si 1.9-2.1%; Mp 0.6-0.9%;

Cr 0.4-0.7; V 0,015-0,20%). The equilibrium temperature of the crucible reaction for this alloy is 1420 ± 10 ° C (design temperature) and is close to the experimental one observed. by the moment of the disappearance of the oxide film On the surface of the melt melted in an argon atmosphere. Ferrocerira were pretreated after overheating of the melt at 1440–1500 ° C, followed by the introduction of ferrosilicobar at a temperature below the crucible equilibrium — 1360 ° C into the filling ladle. The method of graphitization of the prototype included the introduction into the melt of 0.2% ferrosilicobar at 1360 C. The costs of modifying additives for the proposed method were selected on

5 upper, middle and lower limits. The efficiency of the graphitizing treatment was evaluated by the amount of the selected standard sample. The sample has a triangular cross-section with dimensions:

10 mm and bottom 1 mm.

The costs of the tested modifying additives and the results of the comparative tests are tabulated. 55 As follows from the table, additional processing of the molten iron when it is overheated by 20-50 ° C is higher than the crucible reaction temperature at the consumption of ferroceris.

0.005-0.02% by weight of the melt; chillings decrease by 1.5-2 times.

Claims (1)

Formula of b re shadow " The method of graphitizing treatment of cast iron, which includes the introduction of ferrosilicobarium into the melt at a temperature below the crucible reaction temperature. H3BectHbi i Medium 0.1 Editor M.Kelemes Compiled by N. Kostornaya Tehred L. Serdyukova Order .6116 / 26 Circulation 550 VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 characterized in that, in order to reduce chill, before melt processing with ferrosilicobarium, the melt is preheated by 20-50 ° C above the crucible reaction temperature and treated with ferrocerium at its consumption of 0.005-0.02% by weight of the melt. 1360 1430. 28 Proofreader L. Pylypekko Subscription