SU996455A1 - Method for producing high-tensile spheroidal cast iron - Google Patents

Description

(54) METHOD FOR OBTAINING HIGH-STRENGTH IRON WITH SPARKET GRAPHITE

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The invention relates to foundry, in particular, to methods for producing nodular cast iron and can be used in the mass production of critical machine-building castings.

A known method for producing nodular cast iron, which involves melt processing elements with spheroidizing graphite, in a ladle Cll

In this case, increased consumption of expensive modifiers is required, pyro effect and smoke healing are observed. The field of application of methods for modifying high-strength cast iron in a casting mold is limited by high purity requirements for harmful impurities of the original melt. In particular, the use of cupola cast iron is not permitted.

The closest in technical cyie and achievable effect of an image & glue is a method of producing nodular cast iron, which consists of

In the sequential modification of the lithium-iron lump-of gray iron with a graphitizing additive in the ladle and magnesium-containing ligature in the mold. In order to obtain stable mechanical properties and structure of high-strength cast iron from gray cast iron with sulfur content O, O90, 15%, and also to eliminate chill, before modifying the magnesium-containing alloy in the casting mold, when filling K) l of the casting ladle, it is introduced onto the jet of liquid metal ferrosilx barium in the amount of 0.05-0.25% by weight of the liquid metal. The magnesium-containing ligature, for example, iron-silicon, is introduced in the amount of 2–3% of the metal intensity of the form 12 3.

The disadvantages of this method are the high consumption of expensive spheroidizing ligatures (2-3%), which leads to an increase in the metal intensity of the gating system and the lack of stability of the technological process of producing castings from high-strength cast iron using the in-line modification of the npiH process of melting its chemical composition, the last of all on the plasticity of pig iron. The aim of the invention is to reduce the consumption of ligature introduced into the foundry metal form and the metal intensity of the gating system, and to increase the ductility of cast iron with a sulfur content of 0, O5 - to 0.1%. This goal is achieved by the fact that according to the method of producing high-strength nodular cast iron with an ancillary cross-bonding with an ancillary ferrosilicobarium bucket and the subsequent modification of an iron-silicon-magnesium ligature in the casting mold, with a preliminary bucket annealing of the ferrosilicobarium in the mixture with a ferroceride, an anchored gland is introduced in the mixture with a ferro-silicon gougeur, in the case of a preliminary buccal treatment of ferrosilicobarium in the mixture with ferroceride, and in an anchored nodule, mixed with ferro-silicium, is applied in the anchorage of an iron-silicon alloy. -6) (2-1О) - (О,), respectively, in the amount of 0.2-0.1% by weight of the melt, and the iron-silicon magnetic ligature is introduced into the mold On ve, 51, 8% of the mixture of metal Formby introduced into tundish frakhshonnym composition of 0.1-5.0 mm and zhelezokremniymagnievuyu ligature administered in the form as a fraction of 5-10 mm. The fraction of the mixture for bucket processing, on the one hand, is determined by the need to ensure the most complete utilization of screenings. iron – silicon – magnesium alloy upon receipt of a given fraction of a ligature for intraform spheroidizing melt processing (lower limit 0.1 mm) and, on the other hand, ensuring perfect assimilation of the mixture (upper limit 5 mm). A fraction of 5–10 m of a spheroidizing ligature introduced into the mold provides its most complete absorption in a wide range of melt temperatures (from 13OO to 145 ° C). The weight ratio of ferrosilicobar in the mixture is due to the need to ensure a sufficient graphitization effect, which causes an increase in the ductility of cast iron on the one hand, and a subsequent low increase in the achieved positive effect with a higher content of ferrosilicobar in the mixture d on the other hand. The weight ratio of ferronerium 1- (2-6} is due to the need to ensure uniformity of the structure and properties in the casting elements, to increase the mechanical properties of high-strength cast iron with an era content in the initial melt from 0.05 to 0.1% due to deep deacidification and its asthmatic desulfurization (lower limit 1–2) and mixture rise in price (upper limit 1–6). The weight ratio of iron – silicon magnetic ligature is determined, on the one hand, by the need to provide a sufficient degree of desulfurization of the initial melt (lower limit 1–2) and, with On the other hand, the need to ensure acceptable gas and dust emissions in the melt processing zone (upper limit 1-10). Use in the mixture for preliminary treatment of cryolite melt allows cleaning it from the formed reaction products with ligatures and thereby increasing the ductility of the cast iron. cryolite, on the one hand, is determined by the need to ensure the slag liquefaction (the lower limit is 1-0.5) and, on the other hand, by the need to ensure minimum heat loss during melt processing (the upper limit is 1–5). 2). The amount of addition of the mixture introduced into the ladle depends on the initial content of impurities in the melt, in particular sulfur. the mixture is limited, on the one hand, by the need to ensure a sufficient refining and desulphurisation effect of melt processing and obtaining spherical graphite (lower limit of 0.2%) and, on the other hand, by economic considerations, as well as the subsequent small increase, the achieved positive effect, possibly these occurrences of chill off in thin sections of the casting (upper limit 1%). When zapivka melt in the form of a ligature dissolving and modifying the cast iron. The presence of the residual content of rare-earth metals in combination with magnesium coming from the reaction chamber ensures the formation of spherical graphite with a sulfur content in the initial melt of up to 0.1%. The modification in the mold is carried out by an iron – magnesium – magnesium ligature with a magnesium content of 7–9% in the amount of 6.51, 8 of the metal intensity of the form. A reduction in the consumption of modifier compared to the known method for producing high-strength cast iron is possible due to the efficient use of pre-bucket processing. The flow rate of the master alloy is determined by the residual sulfur content in the melt after preliminary bucket treatment. When the sulfur content is O, O1-O, OZ%, it is 0.5-1.2% by weight of the melt, while sulfur is 0.04-0.1%, correspondingly 1.3-1.8% by weight of the melt. Example. To obtain comparative results, two compositions of cast iron are used, with sulfur content in the initial melt of 0, O5 and O, 1%. Melt treatment is carried out in a known manner involving a sequential modifying of the melt with a graphitizing additive (ferrosilicobarium in an amount of 0.15%) and a magnesium-containing ligature in a mold (2.5% of metal mold bones) and the proposed method, including preliminary ladle treatment with a mixture of ferrosilicobar, ferrocerium, and rn. ligatures and cryolite in the ratio, respectively, and the subsequent internal modification of the iron – silicon – magnesium ligature. Moreover, with low social conditions in a raw melt, melt processing in the ladle and in the form is carried out on the lower pretsep values of additives of the mixtures according to the method proposed (respectively 0.2% by weight of the melt and 1% of the metal intensity of the form), and at sulfur concentration up to 0% .on the upper limits (respectively, but 1 and 1.8%). After the bucket treatment, holding the melt in the ladle, slag loading, the molds are made, in the reaction chambers of which there was a c4) aneroidizing ligature. Mechanical test specimens are cut from wedge specimens with a wall thickness of 30 mm. The test results are reiterated in the table.

Oh o5

The proposed 0.1%

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Claims (2)

56, O 3.0 53.0 55 The application of the proposed method allows to stably obtain the structure of spherical graphite at sulfur concentrations up to 0.1%. The properties of cast iron correspond to the grade B45Q-2. At the same time, when modifying by a known method, such defects as black spots (when the sulfur content is higher than 0.05%), structurally free cementite appear in the castings, and there are zones with a lamellar graphite structure. This I leads to a sharp decrease in the mechanical properties of cast iron, especially plastic characteristics. The proposed method rbeo; bakes the absence of cementite in the structure of castings with a wall thickness of over .5 mm, reducing the consumption of ligatures introduced into the mold. It was established experimentally that when the sulfur content is up to 0.05%, the minimum consumption of iron-silicon magnet for internal modification by this method is 0.5-1%, according to the known 2% -2.5%. And when the sulfur content is from O, 05 to O, 1, these values are 1, 5% and 2.5-3%, respectively. The application of the proposed method for producing nodular cast iron ensures stable production of high mechanical properties of castings at a sulfur concentration in the ishohan melt of up to 0.1% and reduction of the scraping: of metal to the gating system. The economic effect of shchmeneniya proposed method in comparison with the known is 15 rubles. on 1 t. suitable to pour. Claims 1. A process for producing ductile cast iron with nodular graphite, off conductive provisional ferrosilikobariem ladle treatment and subsequent modification in the mold zhelezokre niymagnievoy ligature, characterized -If it, that in order to reduce the flow ligatures introduced into the mold and runner system of metal to increase the ductility of cast iron with sulfur content from O, O5 to 0.1%; during preliminary bucket treatment, ferrosilicobarium is introduced in a mixture with fer sulfur, iron-silicon magnesium league, tour th and cryolite in a ratio of 1:: {2-6): (2-10): (O, 5-2), respectively, in an amount of 0.2-1.0% by weight of the melt, and iron-silicon magnet alloy in the mold is introduced in the amount of 0.5-1.8% of the metal-form. 2. The method of claim 1, wherein t and h and and so that the mixture is introduced into a bucket with a fractional composition of 0.1-5 mm, and the iron-silicon alloy is introduced into the form in the form of fractions of 5-10 mm. Sources of information taken into account in the examination 1. US patent number 3851700, cl. B 22 D 27 / 2O, 1972. 2. The author's svietelstvo USSR 676623, cl. From 21 to 1/00, 1978.