SU1440947A1 - Modifying additive - Google Patents

Abstract

The invention relates to foundry and can be used in the manufacture of castings from high-strength cast iron with spherical and vermicular graphite by modifying in the form. The purpose of the invention is to improve the mechanical properties of high-strength cast iron obtained by modifying in the mold. The modifying mixture contains magnesium, silicocalcium ,. REM alloy, aluminum and ferrosilicon in the following ratio of components, wt.%: magnesium 10-22, silicon-calcium 1-4, alloy FSZORMSO 4-4, aluminum 35-75, ferrosilicon - the rest. Additional input of aluminum into the composition of this mixture when changing the ratio of other components provides higher (by 25–30%) mechanical properties of cast iron by reducing the amount of slag inclusions, reducing chill, and improving the form of graphite. 2 tab. //

Description

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The invention relates to foundry and can be used in the manufacture of castings from high-strength cast iron with spherical and vermicular graphite by the method of modifying in a mold.

The purpose of the invention is to improve the mechanical properties of high strength over the obtained modification in 10 form o

The modifying mixture containing magnesium, C-shicocalcium, PZS and ferrosilicon alloys, additionally contains aluminum in the following ratio tS of components5 wt,%:

Magnesium 10-22

Silikokaltsy 1-4

Alloy FSZORZMZO, 1-4

Aluminum35-75 20

Ferrosilicon - - Else

Aluminum acts as a refining, alloying and graphitizing element; possesses a large chemical agent for oxygen5, which contributes to the formation of refractory oxides, bonding oxygen dissolved in liquid iron. The presence in the mixture of an alloy of FSSORMA and aluminum in the specified amount creates an anti-carbide-forming effect, contributing to the poluneniye of castings without chill. Aluminum simplifies the process of producing pig iron with vertical graphite, because without this component, the production of such cast iron 35 with the introduction of magnesium into the metal is insufficient for complete spheroidization of graphite S without the technological

The nuky limit of the content of aluminum in a mixture of 40 (35%) is due to the need to produce thin-walled castings without screening, and the top (75%) - to obtain the smallest amount of ferrite to increase the strength of cast iron in castings — preventing pollution castings with nonmetallic inclusions. The smaller the modifier of magnesium and rare-earth metals, the lower it can be the content of alu gt Q mini, and vice versa.

Magnesium in the composition of the modifying additive contributes to obtaining the pre-vermicular and spherical forms of graphite in the cast iron. Its lower content in the mixture (10%) provides the required form of graphite in all portions of the cast iron, and at

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With a magnesium content of more than 22%, the modification reaction proceeds with metal splashes through a hundred k.

Silicocalcium in the mixture contributes to the production of castings without defects such as black spots, with a smaller volume of shrink holes. When the content of silicocalcium in the mixture is less than 1%, black spots are observed in the castings, and if it is contained in the mixture of more than 4%, there is a risk of damage to the castings with non-metallic inclusions.

The alloy of rare-earth metals tmpa FSZORMZOZA was introduced into the modifier to neutralize the harmful effect of deglobulator elements in the original cast iron (titanium, bismuth, etc.) and to stabilize the results of the modification. With a content of less than 1% of the indicated alloy, the desferonizing effect of these elements is not completely eliminated, and the structure and properties of the modified cast iron are unstable. The upper limit of the content in the modifier alloy FSZORZM (4%) is limited by the risk of the occurrence of carbides in the cast iron structure, especially at the same time increased magnesium content.

Experimental data showing the advantages of the proposed modifier are given in Table 1 for the production of high-strength nodular cast iron (VCHSHG) and in Table 2 for the production of high-strength iron with the vermicular graphite (VCGH).

The original cast iron electrofusion melting upon receipt of the high-temperature iron group contained,%: 37 80 carbon; 0.45 manganese; 2.38 silicon; 0.04 chromium; 0.03 phosphorus; 0.025 sulfur.

Powdered (fractions up to 1 iM) components (magnesium, ferrosilicon, Silicocalcium, REM alloys) of the admixed additive were mixed and placed inside the aluminum shell. The size of each of these bags was 4-5 mm in diameter, 6-15 mm in length.

The components of the prototype modifier of grinding-Ali to fractions of 1-5 mm and evenly mixed. Modifying additives were also placed in the reaction chambers of the casting molds (dissolution factor 0.06 ± 0.01 kg / cm s when receiving LPSG and 0.4% when receiving VCG). The temperature of pouring the metal into molds is 1440 ± 15 ° C. Cast flat samples

 1440947

Type I according to GOST 7293-79 for the determination of cementite (test 7). Modification NIN mechanical properties of cast iron. torus prototype provides low and

In tab. and 2 experiments 1 - A correspond to the claimed, 5 - 7 - to the specific compositions of the modifying mixture, and 8 and 9 - to the prototype mixture. From these tables it can be seen that upon receipt of the Ч VCHSH, the claimed modifier provides for obtaining spherical shape 10 of graphite (SSG 90–95%) of high tensile strength (550–570 MPa). and high elongation (4.0-5.5%). When the additive composition deviates from the claimed form, graphite 15 is not completely spherical (experiments 5 and 6) or there are inclusions of cementite (experiment 7), therefore, the indicators of the properties of cast iron are lower. When using the prototype modifier, despite 20 high SSG value of 85 - 90%, the properties of cast iron are low due to the presence of slag inclusions (experiment 8), caused by high content of silicocalcium, or chilled castings (experiment 9). 5 i When obtaining VChVG (Table 2), if the composition of the additive deviates from the claimed form of graphite, experiments 5 and 6 worsen) or in the structure of cast iron

properties of cast iron due to blockages with slag inclusions and chillings of castings (tests 8 and 9),

The preparation of spherical or vermicular forms of graphite in the cast iron structure and its high mechanical properties is achieved by varying the flow rate of the additive.

Claims (1)

Invention Formula A modifying mixture containing magnesium, silicocalcium, an alloy of rare-earth metals and ferrosilicon, characterized in that, in order to improve the mechanical properties of high-strength cast iron obtained by modifying in the form, it additionally contains aluminum in the following ratio, wt.%; . Magnesium 10-22 Silikokaltsy 1-4 Alloy RZM1-4 Aluminum35-75 Ferrosilicon Rest is cementite (test 7). The modified prototype provides low properties of cast iron due to blockages with slag inclusions and chillings of castings (tests 8 and 9), The preparation of spherical or vermicular forms of graphite in the cast iron structure and its high mechanical properties is achieved by varying the flow rate of the additive. Invention Formula A modifying mixture containing magnesium, silicocalcium, an alloy of rare-earth metals and ferrosilicon, characterized in that, in order to increase the mechanical properties of high-strength cast iron, obtained by modifying in the form, it additionally contains aluminum in the following ratio, wt.%; . Magnesium 10-22 Silikokaltsy 1-4 Alloy RZM1-4 Aluminum35-75 Ferrosilicon Rest Table 1 15 10 18 22 8 10 23 4 2 one 0.5 5 1.5 4 3 one one 0.5 53 35. 65 75 35 80 33 IiJjiflKOBbie enable Art. - 95 90 90 95 75 80 90 15,560 4.5 Oh oh Oh oh 20 15 ten 550 5.5 575 4.4 575 4, O 15 455 1.4 15 460 1.8 5,470 0.9 Slag processing Table 2