SU1359306A1 - Method of inoculating cast iron - Google Patents

Abstract

This invention relates to metallurgy and foundry, in particular, to the technology of modifying pig iron to produce iron with vermicular graphite. The purpose of the invention is to obtain iron with vermicular graphite, reduce the propensity of iron with a sulfur content of up to 0.06% to metastable crystallization, reduce labor intensity and increase productivity. Processing of cast iron provides for the simultaneous introduction of ligatures of rare-earth metals and magnesium-containing ones. The amount of magnesium injected is determined depending on the initial sulfur content in the iron, and the amount of the alloy introduced in the iron is calculated from the ratios as a percentage of the mass of liquid iron: Kp ,, 04 lOO / N ,, .Kn (3 + 0.02). lOO / N, where Кр, is the amount of the introduced ligature, including REM; the amount of injected magnesium ligature; S is the% sulfur content in the original cast iron, 0.04% the content of REM introduced into the cast iron, (3 + 0.02) -% - the Mg content introduced into the cast iron, N, -% the content of REM in the ligature, N is the% Mg content of the ligature. Using. This method reduces the amount of expensive input ligature of rare-earth metals and reduces the propensity of cfg to carbide formation, which eliminates the need for re-modifying and improves the performance of the process. Table I (O CO co. Eats co o P5

Description

The invention relates to metallurgy and foundry, in particular, to a process for the modification of pig iron for producing iron with vermicular graphite (CGF).

The purpose of the invention is to obtain iron with vermicular graphite, reduce the propensity of iron with a sulfur content of up to 0.06% to metastable crystallization, reduce labor intensity and increase productivity.

The proposed method carried out the modification of cast iron with a sulfur content of up to 0.06% at a treatment temperature of 1400-1500 ° C with ligatures of rare-earth metals with a content of rare-earth metals of 20-30% of the grades СЦЕМИШ-1, СЦЕМИШ-2, СЦЕМИШ-3 and magnesium containing Magnesium 5.5-12.5% MajloK ZhKMK-1-ZhMK-b.

Examples of processing of cast iron by the proposed method in comparison with the method of processing of cast iron with a ligature of rare-earth metals with and without secondary modification and the characteristic of the tendency of pig iron to carbidization, estimated by chipping value from the technological sample, are presented in the table

The ratios, determined by the number of ligatures, are derived empirically for the modification of cast iron - with ligatures of rare-earth metals with a content of rare-earth metals of 20-30% and magnesium-containing: with ligatures with a magnesium content of 5.5-12.5% with a sulfur content in the original cast iron up to 0.06%.

When ligatures are added, according to the calculated ratios, when the initial sulfur content in the iron changes, only the amount of magnesium-containing ligature that is introduced changes, while the addition of rare-earth metals remains unchanged, due to which it is possible to control the iron's tendency to metastable crystallization and eliminate secondary (graphitizing) modification and heat treatment .

As can be seen from the table, due to the cumulative effect of rare-earth metals and Mg, the amount of rare-earth metals that must be introduced to obtain cfg is reduced by 5-10 times, and, thus, the inclination of the pig iron to carbide formation, which is characterized by the observed

chill on the wedge-shaped sample (and the need for the introduction of de-globularizing agents with the introduction of the magnesium ligature is excluded). In addition, when processing the cast iron by the proposed method, the structure of the CVG is stably provided with the following mechanical properties: the tensile strength is not lower

350 MPa; relative lengthening is not lower than 3.0%; hardness 140-180 HB.

Thus, the advantages of the invention are to reduce the amount of expensive injected ligature of rare-earth metals and reduce the propensity of cfg to carbide formation, which eliminates the need to re-modify and provides improved process performance.

Claims (1)

Invention Formula Method of modifying pig iron, including simultaneous processing pig iron ligature REM and magnesium ligature, characterized in that, in order to obtain iron with vermicular graphite and reduce the tendency of iron with sulfur content to 0.06% to metastable crystallization, reduce labor intensity and increase productivity, the amount entered in the cast iron ligatures are established from the correlation of the NII,% by weight of liquid iron TO  0, rs and, - (S + 0.02) -100 KMJNo where Kr - the number of input ligatures, including rare-earth metals; TO,,. - the amount of injected magnesium ligature; 5 percent sulfur content to 0.06 in the original cast iron; content of rare-earth metals injected into cast iron,%; Mg content introduced into cast iron,%; REM content in ligature,%; Mg content in ligatru,%. 0  S 0.04 - S + 0.02 N, and. 32 REM 25 REM 32 REM СЦЕМИШ-2 0.5 Bleed across the height of the wedge СЦеМШ-2 0.5 and secondary modification by ferrosilicon FS-75  (STSISH-1) 0.16 K „(ZhKMK-3) 0.4 m СЦЕМИШ-1 0.9 Bleed across the height of the wedge STsMISH-i 0.9 and secondary modification by ferrosilicon FS-75 3-8 СЦЕМИШ-2 1.4 Bleed across the height of the wedge СЦЕМИШ-2 1,4 and secondary modification by ferrosilicon FS-75 3-8 3.70 2.32 0.50 0.06 0.05 25 REM 12 Mg Cr, (STsISH-1) 0.16 Kd, (ZhKMK-3) 0.6 25 REM СЦЕМИШ-I СЦЕМИШ-1 1,4 and secondary modification by ferrosilicon FS-75 Compiled by A. Minaev Editor M. Kelemesh Tehred L. Serdyukova Proofreaders ut. ha Subscription Order 6116/26 Circulation 550 VNIIPI State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5  printing company, Uzhgorod, st. Project, 4 Production 0-3 1.4 Bleed across the height of the wedge 3-8 Subscription