SU1129023A1 - Modifier for centrifugal casting of iron billets - Google Patents

Description

f I The invention relates to a foundry, the manufacture, in particular, to the technology of centrifugal casting of cast iron billets, for example cylinder liners of internal combustion engines. Known modifier for centrifugal casting of cast iron blanks |) composition, weight. %: Metal oxides25-30 Antimony. 40-55 CryolitEstal The disadvantage of this modifier is the complexity of its preparation for use, since preliminary thermal preparation is required, requiring the use of special containers. In addition, the introduction of metal oxides often leads to an increase in the number of nonmetallic inclusions in the surface layer of the metal. The closest to the present invention is the use as a modifier for the centrifugal casting of pig-iron billet ferrosilicon grade FS 75 2. However, the use of ferrosilicon. in pure powdered form as a modifier for centrifugally casting billets of cast iron is associated with the growth of its 1M waste and interaction with the atmosphere of air on the trough of the casting device and in the cavity of the mold. As a result, chipping of the surface layer of the casting appears, its workability deteriorates, and the yield of defective products increases. The aim of the invention is to reduce scrap casting and improve the quality of the casting. ; The goal is achieved by the fact that the modifier of centrifugal casting of cast iron billets, including ferrosics (picies, additionally contains sodium fluoride or cryolite at the following ratio of components, wt.%: Ferrosilicon 70-80 Sodium fluoride or cryolite 20-30; Sodium fluoride in the composition of the modifier, it performs two roles: first, it covers particles of solid ferrosilicon supplied to the cast iron with a fusible film, which protects it from oxidation and promotes the bulk processing of cast iron. Secondly, the sodium fluoride melt protects the iron surface is oxidized, at the same time it assimilates nonmetallic inclusions well, which ensures uniformity of the metal composition of the casting surface, as a result, the likelihood of chipping of the surface layer of the casting and the formation of cracks or difference in hardness on it is reduced, and consequently, its workability and rejects are improved Content in modifier sodium fluoride or cryolite less than 20% does not provide n-sweat film on the surface of the melt, and its content of more than 30% complicates the introduction of the modifier into the liquid cast iron, since the excess, low-melting flux obstruction is sprues casting device. . The content in the composition of the modifier ferrosilicon less than 70 wt.% Is not enough to affect the degree of graphitization, size and distribution of graphite. The effect of ferrosilicon as a modifier increases. with an increase in its quantity. However, to introduce the era in the liquid me-. tb cbbmie 80 may. The% modifier is not rational, since the irrecoverable loss of ferrosilicon sharply increases. The resulting silicon oxides together with the oxides of calcium and aluminum increase the viscosity of the liquid flux. Example. The modifier is a mechanical mixture of ferrosilicon gt and sodium fluoride. Before dosing the modifier, its components are dried at 300-400 ° C, milled in ball mills to a fraction of more than 1.0 mm and thoroughly mixed in the required proportions. Ferrosilicon use brand FS 75 (GOST 1415-78), and sodium fluoride grade 1 (GOST 21871-75) .. Cast by centrifugal method and investigated 6 batches of billets of cast iron brand SC-21-40. In the process of pouring the cast iron into the mold, the modifier is metered to the liquid metal batch. Its consumption is determined experimentally and is 0.3-0.4% by weight of the metal.

1 1129023

. The billets are cast with an internal hardness measurement. It is produced with a diameter of 112 mm and a wall thickness through every 4 mm, beginning

.16 mm. The thickness of the lining layer on the outer surface. Definition2,5 mm, the temperature of the cast iron in the distribution of the effect of the composition of the modifier on

exact bucket 1330 S. On the jet metal-j micro and macrostructure of the metal,

la serves the modifier in the amount of results; results of studies are given0.5% by weight of the metal. us in the table.

7 11290238

It follows from it that the greatest quality is, however, on the inner surface of the billet without chilling, the castings are found to be part of a uniform hardness across the section with slag impurities and sulfoil produced with use of inclusions.

4 and 5. Flux compositions. Metallography-5 Rejection of casting blanks

A weighty analysis confirms the chill-out and crack structure compared to

metal homogeneity over the cross section by the use of known modification modifits .jTopa is reduced by 4-8%, reducing

The modifier consisting only of allowances for the mechanical treatment of ferrosilicon (composition 1) and its removal by 10-15%, which ensures 65% FS-75 and 35% NaF (composition 6) to ensure the economic effect on

bake casting blanks without. from-making each liner 0.1 rub.

Claims (1)

(54 MODIFIER FOR CENTRIFUGAL CASTING OF PIG-IRON Billets, including ferrosilicon, t and h a rant and the fact that, in order to reduce casting defects and improve the quality of casting, it additionally contains; contains sodium fluoride or cryolite in the following ratio of contents components, wt.%: Ferrosilicon h 70-80 Sodium fluoride or cryolite 20-30