RU1822444C - Master alloy for treatment of molten iron - Google Patents

Abstract

Usage: in the production of cast iron with vermicular and spherical graphite. SUMMARY OF THE INVENTION: Cast iron contains a nitrogen-containing substance of 3-30%, a graphite powder of 0.5-6.0, a magnesium alloy, and the rest. As a nitrogen-containing substance, carbamide, dicyandiamide, urotropine are used. 1 e.p. F-ly, 2 tab.

Description

Ioobrenie refers to the foundry, in particular to the foundry of cast iron with vermicular and spherical graphite by treating the initial melt in the furnace, ladle or reaction chamber of the casting system of the casting mold with the contacted reagents, which include a ligature containing magnesium.

A magnesium briquette is known for producing high-strength cast iron, consisting of waste magnesium chips and binder (a mixture of 20-30% magnesium oxide powder and 70-80% sodium silicate solution), the briquettes are cylindrical in shape and contain more than $ 87 magnesium.

The disadvantages of the known magnesium briquette include the fact that when it is dissolved in the molten iron, a large amount of slag is formed, since the binder is completely converted into slag and that it does not provide high strength and crack resistance in castings, since magnesium is not a metal matrix reinforcing cast iron element.

The closest in composition to the proposed one is a compacted reagent for treating cast iron melt, consisting of magnesium ligature, for example, silicon gel-silicon alloy, graphite powder - in total 75-P5 May. and a binder of 15-25%, clay is used as the binder. This compacted reagent has the same disadvantages as its analogues - a large amount of slag formed during the processing of cast iron and the impossibility of obtaining high strength and crack resistance of cast iron in castings. The binder of the reagent is clay, when the briquette is dissolved in the cast iron, it completely passes into the slag, thus polluting the cast iron and increasing the likelihood of castings marriage. Bottom

Ј

00

go

TO)

04

The strength and fracture toughness of cast iron are caused by the fact that the substances that make up the reagent do not provide perliteration of the metal base of cast iron.

The aim of the invention is to reduce the amount of slag formed during the processing of cast iron and to increase the strength and crack resistance of cast iron.

The proposed compact reagent containing magnesium ligature, for example, silicon-magnesium alloy, graphite powder and a binder, use a nitrogen-containing substance with a temperature of destruction below the temperature of the treated cast iron as a binder, in the following ratio, wt.%: Nitrogen-containing substance3 30

Graphite powder 0.5-6.0 Magnesium ligature Else. As a nitrogen-containing substance, carbamide, dicyandiamide, urotropine are used.

The use of a nitrogen-containing substance as a binder with a temperature of degradation below the temperature of the treated cast iron reduces the minimum amount of slag generated during the processing of cast iron, since the products of the destruction of the nitrogen-containing substance are atomic nitrogen and diatomic gases that do not form a slag phase on the surface of the melt. Atomic nitrogen has a high chemical activity, dissolves in iron, shows alloying properties with respect to it, perlitizes the metal base, increasing the mechanical properties of cast iron, namely strength and crack resistance.

i

The advantages of the present invention were checked by performing experiments on the treatment of cast iron melts with compacted reagents of known and proposed compositions, with an assessment of slag formation during processing and subsequent analysis of the structure and properties of cast iron. The experimental melts were carried out in the foundry of the Institute for Problems of Pouring, Academy of Sciences of the Ukrainian SSR, in 150 kg of an induction crucible furnace with acid lining. The experimental conditions were maintained identical when used for cast iron processing

5

0

S

0

5

on the proposed and well-known reagents. By remelting the mixture, a melt was obtained containing wt.%: C 3.4-3.6; Si 0.8-1.0; MP 0.4-0.5; P 0.05-0.08; Cr 0.1; S 0.01-0.20; N 0.004-0.006 .. The melt was overheated to a temperature of 11 50 ± 20 ° C (the temperature was controlled by a thermocouple), the slag was cleaned and treated with a compacted reagent introduced on a L-shaped rod into the bottom of the crucible of the furnace, in the form of cylinders with a diameter of 80 mm and a height of mm . After completion of the dissolution of the compacted reagent in cast iron, slag was removed from the surface of the melt, gas samples were taken, and the metal was poured into sand and clay forms where cast iron was crystallized. The castings had a wall thickness of 30 mm; after freezing, samples were cut from them for mechanical testing to determine the tensile strength and crack resistance. The slag cleaned from the surface of the metal after processing it with a reagent was weighed and thus, slag formation was evaluated.

The compacted reagents of the proposed and known compositions were made by powder metallurgy methods. As a binding known reagent, kaolin clay was used; the proposed reagent was urea, dicyandiamide, urotropine; data on their destruction temperatures are given in table. 2. The base used was crushed to fractions 0.1-3 mm magnesium alloys and graphite powder with a particle size of less than 1 mm. The results of the experiments are given in table 1. The consumption of compacted reagents for treating cast iron in each experiment was chosen so as to ensure that 0.12 wt.% Of magnesium was introduced into the melt.

As a result of using the proposed compacted reagent, in comparison with the test reagent, slag formation decreased from 1.24 kg to 0.77 kg, tensile strength increased from 617 MPa to 692 MPa, and crack resistance increased from 58.1 to 67.0 MPa-m0 5.

0

5

0

5

0

Claims (2)

1. A compacted reagent for treating cast iron melt, consisting of magnesium ligature, graphite powder and a binder, characterized in that, in order to reduce the amount of slag formed during the processing of cast iron and increase the strength and crack resistance of cast iron, nitrogen-containing is used as a binder a substance with a temperature of destruction below the temperature of the treated cast iron in the following ratio of components, May.%: Q22bMb Nitrogen-containing substance 3-30 Graitite Powder 0, Magnesium Ligature Else 2. The reagent according to claim 1, characterized in that carbamide or dicyandiamide is used as the nitrogen-containing substance; or urotropin. . Experience Mr. I flopped with an ilvstny composite reagent, experiments C 2 - 12 - with small iron and chemical reactants; P.OM - perlite, ferrite, cementite, respectively; UQ is the tensile strength at growth; Kjc treadmill YM - absorption of magnesium by cast iron; N „- source eodermiya ayut vyrywv I, - of course, the co-op "Niv Mot" cast iron. We are Nassa Obraummgos after processing cast iron; c ° AeP IJtHH magin and cast iron low tide; Ј .. with AI 4 and correspondingly) 1 ateli. 6 experiments V 2, 10, II, 1 for the purpose of the invention were not achieved, since experiment 2, 10 contained the sauthe auxiliaries, G 11, 18 the content of the defect “it pyodilo aa 1a . In experiments Г 1-) В, 21 and 22 keestee psioa of the compoite reagent ftcrKwibtoeaHa ligature composition, us .: And "7, SI SO, Al 0.3, Fe ost.  in experiments G 19, 20, test alloys of the following composition, us A: and in experiment W 19 M 7, Si 50, Al 0.3, B 4, Fe ost., in experiment G 20 Hfe 7, Si SO, Al 0.3 , REM 0.5, Fe ost. In experiments If 2–20 as св ow св го оль ел оль оль оль оль оль оль и и и е е е е, e 21 - dicyandmachia, and 9 22 - urotro Table I 1822M1 table 2