SU1574673A1 - Malleable cast iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the production of ductile iron castings. The purpose of the invention is to increase the tensile strength and ductility. New cast iron contains, wt%: C 2.4 - 2.8

SI 1 - 1.4

MN 0.8 - 1.0

AL 0.01 - 0.02

BA 0.015 - 0.025

NA 0.003 - 0.006

FE - the rest. The addition of BA and NA to the composition of cast iron makes it possible to increase σ _{in by} 1.02-1.15 times and δ by 1.7-2.3 times. 2 tab.

Description

t

(21) 4434766 / 31-02

(22) 04/18/88

(46) 06/30/90. Bul 24

(71) Gorky Polytechnic Institute

(72) V.L. Korovin, V.N.Kolganov

and A.V.Bolshakov

(53) 669.13-196 (088.8)

(56) USSR author's certificate

No. 502971, cl. C 22 C 37/10, 1974.

USSR Author's Certificate No. 654691, cl. C 22 C 37/10, 1979.

(54) KOVKY IRON

(57) The invention relates to metallurgy and can be used in the production of ductile iron castings. The purpose of the invention is to increase the tensile strength and ductility. New cast iron contains, wt%: C 2.4-2.8; Si 1-1,4; Mp 0.8-1.0; A1 0.01.-0.02; Ba 0.015-0.025; Na 0.003-0.006; Fe - the rest. The addition of Ba and Na to the cast iron makes it possible to increase the GBS by 1.02-1.15 times and $ 1.7-2.3 times. 2 tab.

This invention relates to metallurgy, in particular to the development of ductile iron compositions.

The purpose of the invention is to increase the tensile strength and ductility.

The choice of the boundary limits for the content of additionally introduced components in the iron of the proposed composition is determined as follows.

The introduction of barium in the range of 0.015–025 wt.% Allows refining the metal more qualitatively, provides an increase in the number of grouting centers, improves the annealing carbon shape and thereby contributes to an increase in the strength and ductility of ductile iron.

The introduction of sodium in the range of 0.003- 0.006 wt.% Leads to acceleration of the process of reducing iron oxides,

manganese (catalytic action), helps to reduce viscosity of the ишsakovs due to the destruction of complex anions in them. The low viscosity of the resulting slags makes it possible to produce higher quality metals by non-metallic inclusions by gases. Sodium has a high chemical activity and has a modifying effect on the metal.

Increasing the content of barium more than 0, T) by 25% and sodium more than 0.006% leads to an increased formation of non-metallic inclusions to such an extent that, besides increasing the centers of graphization, (some non-metallic inclusions fulfill this role) they contaminate metal , deteriorating its quality characteristics and reduce the tensile strength and relative elongation of cast iron.

p j

Ј About J

The presence of barium in the iron below 0.015% and sodium below 0.003% leads to deterioration in the shape and coarsening of carbon annealing and, consequently, to a decrease in the tensile strength and relative elongation of the iron.

Barium and sodium, actively reacting with sulfur, change the value of the ratio of manganese to sulfur, which determines the amount of manganese left to form a pearlite component. In addition, sodium contributes to the recovery of manganese.

The compounds of barium, sodium, and manganese sulphides, formed in iron, act as active nuclei of graphite, grinding and rounding it.

The proposed cast iron is melted in a 120 kg induction electric furnace.

As the charge materials, pig iron and cast iron, steel scrap, ferromanganese and ferrosilicon are used.

Changes in the content of aluminum, boron, barium and sodium in the alloy were achieved by introducing aluminum, boric acid, barium carbonate and technical soda into the casting ladle during its filling.

Samples for mechanical tests are poured into sand-clay forms at a temperature of liquid metal of 1450 ° C.

Cast iron of the known and proposed compositions was annealed to a pearlite structure in an electric elevator industrial furnace with a total cycle of 26 hours.

Cast iron

Chemical composition, wt.%

,

five

0

five

0

0

five

on the famous shop mode. The heat treatment mode is as follows: heating to a temperature of the order of 940 ° C for 13 hours, holding at this temperature for 6 hours, intermediate cooling for 1 hour and smooth cooling from 750 ° C to 730 ° C for 6 hours.

The structure of cast iron samples after annealing is up to 96% granular pearlite (partially plate pearlite in the decomposition stage), annealing carbon and residual ferrite up to 10%.

The chemical composition of the proposed and known iron and their mechanical properties after annealing are given in table. 1 and 2 respectively. According to the table. 2 it follows that the cast iron of the proposed composition due to the additional input of Ba and Na provides an increase in tensile strength (6G6) by 1.02-1.15 times and plasticity (o) by 1.73-2.3 times.

Claims (1)

Claims Malleable cast iron containing carbon, silicon, manganese, aluminum and iron, characterized in that, in order to increase tensile strength and ductility, it additionally contains barium and sodium in the following ratio, wt.%: Carbon2.2-2.8 Silicon 1.0-1.4 Manganese 0.8-1.0 Aluminum 0,01-0,02 Barium0.015-0.025 Sodium0,003-0,006 IronErest Spreadsheets 460 440 380 470-5,505 table 2 180 200 210 190,200 220