SU1224349A1 - Briquette for cast iron inoculation - Google Patents

Description

The invention relates to metallurgy, in particular to the search for modifier compositions for the production of high strength iron.

The aim of the invention is to increase the solubility of the modifier, as well as the strength and ductility of cast iron and the elimination of the section.

Example. Briquette modifiers are prepared by compressing components that have been pre-ground to fractions less than 2-4 mm and evenly mixed; at the same time, metallic magnesium, copper, molybdenum, iron, being plastic components, during deformation, deform, coalesce and form a solid framework, inside of which there are xr resistant components (alloys of rare-earth metals, flux, ferrosilicon) pressing, depending on the percentage of ductile and fragile components of its composition.

The limits of magnesium content in the briquette (3-15%) are chosen to ensure high absorption in the iron. With a content of less than 3% magnesium in the modifier, as established by experiment, spheroidal graphite is not obtained, and at 15% of this element, its absorption in cast iron decreases due to large evaporation losses.

Copper, nickel and molybdenum, included in the briquette in the form of powder or. small fractions (chips, cuttings, granules, etc.), play the role of alloying elements and prevent the formation of carbides in the cast iron structure, and as a result of pressing the mixture, are plastic components, along with magnesium briquette, to form a solid frame in it. The lower limit (20%) of these components is the allowable amount below which the required strength of the briquette is not achieved. In addition, the use of the content in the briquette individually or in the sum of copper, nickel and (or) molybdenum, the strength of cast iron is much lower, especially in the case of massive castings. The upper limit (65%) of copper, nickel, and molybdenum is limited; the presence of certain quantities of other components in the briquette, including ferrosilicon, which contributes to an increase in the graphitizing method

modifier, grinding the structure and increasing the ductility of cast iron.

RZM alloys of the FSZORZM type with a content of 15–35% of REM were introduced into the briquette to neutralize the known antisphorodizing effect of copper, increase the number of graphite inclusions in the iron and increase the mechanical properties of the latter. At the same time, less than 1% of REM alloys do not have a noticeable positive effect, and with more than 6% of REM alloys, there is a danger of the occurrence of carbides in cast iron.

Flux, such as hydrofluoric acid, improves solubility and assimilation of the briquette in the cast iron, with a content of less than 1% of the flux, this effect is not observed, and with more than 8% of its content in the briquette, the dissolution rate of the latter is excessively large, and, in addition, metal is observed non-metallic inclusions due to low viscosity slags.

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Iron (in the form of powder, fine chips or granules), being a refractory component, slows down the dissolution and evaporation of magnesium, and also plays an additional role as a keeper. The content of iron in the briquette, like ferrosilicon, depends on the amount of other components.

To test the effectiveness of the modifier of the briquette of the proposed composition under production conditions, it was tested against the briquettes of known compositions.

Test modifier-briquettes

0 carried out under the same working conditions: cast iron of an electric smelting furnace at 1450-1470 C was treated in a ladle with silicon-containing ferroalloys (CMg type ligature according to TU 14-55 134-81 and FS75 ferrosilicon according to GOST 1415-78) I obtained melt (composition,%: carbon-3.6-3.8, silicon 2.5-2.6, manganese 0.65-0.70, chromium 0.05-0.12, sulfur 0.01-0.02) with temperature

0 UOOilO C after 20-25 minutes after such pre-treatment was poured into molds, in the gating system of which briquette modifiers were previously placed. The mass of each briquette was 1000 + 25 g; the number of briquettes in each form was determined by its metal intensity at the rate of the briquette modifier consumption of 0.354

0.02% by weight of cast iron. The filling time was 5515 s.

The chemical composition of briquettes and the results of determining the depth of chill cast iron treated with the studied briquette modifiers on wedge samples, data on specific solubility (in g / s) and mechanical properties of cast iron after modification are shown in the table.

The table shows that the dissolution rate of the briquette of the proposed composition (Nos. 1-6 and 11-17) is

17-24 g / s, and the prototype modifier (No. 9) 10 g / s. The chill depth of the wedge samples is no more than 2 mm for the proposed modifier and 40 mm for the prototype (No. 9).

The use of the modifier-briquette of the proposed composition allows to exclude the operation of heat treatment of cast iron, increase its (on average by 25%) absorption in the cast iron, to obtain (by 8-14%) greater strength and higher (2-3 times) ductility of cast iron in compared with the famous.

Claims (3)

1. BRIQUET FOR MODIFICATION OF IRON, containing magnesium, flux and iron; characterized in that, in order to increase its solubility, as well as the strength and ductility of cast iron and eliminate bleaching, it additionally contains an alloy containing rare-earth metals (FSZORZM), ferrosilicon (containing 42-78% silicon) and one or more elements from the group consisting of copper, nickel, molybdenum, in the following ratio of components, May.%: Magnesium 3-15 Flux 1-8 Alloy containing rare earth metals (FSZORZM) Ferrosilicon (containing 42-78% silicon) One or more elements from the group consisting of copper, nickel and molybdenum Iron 2. The briquette according to claim 1, with respect to the fact that it contains 1-6 10-35 20-65 The rest and the most rare-earth metal alloy containing 15-35% of the rare-earth metals of the cerium group (75-85% cerium, the rest is lanthanum, praseodymium, neodymium). 3. Briquette pop. 1, about. It is consistent with the fact that it contains fluorspar as a flux.