SU1062295A1 - Cast iron - Google Patents

Abstract

CAST IRON containing carbon, silicon, manganese, chromium, nickel, vanadium, nitrogen, titanium, rare earth metals and iron, characterized in that, in order to improve wear resistance in aggressive media containing sulfur dioxide and carbon dioxide, it additionally contains antimony at the following ratio of ingredients, wt.%: 2.9-3.5 Carbon 1.7-2.7 Silicon O, 3-0.8 Manganese 0.1-0.8 Chromium 0.05-0.8 Nickel 0, 15-0.5 Vanadium with S 0.005-0.02 Nitrogen 0.02-0.15 Titanium (L Rare Earth 0.005-0.02 Metals 0.005-0.3 Antimony Remaining Iron

Description

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The invention relates to metallurgy, in particular, to compositions of high carbon iron alloys, and can be used for the manufacture of especially responsible castings, working under conditions of friction, sliding in an aggressive environment of sulfur dioxide (COL) and carbon dioxide (COj). .

High-carbon iron alloys containing silicon, manganese, chromium, vanadium, titanium and nitrogen are known in the foundry industry. These alloys, due to complex doping with carbide-forming elements, have high mechanical properties 1–2.

However, the alloys have inadequate wear resistance and corrosion resistance in friction pairs, which work under especially heavy conditions — elevated temperatures, high specific loads, and an aggressive atmosphere of sulfur dioxide and carbon dioxide.

The closest to the proposed technical essence and achievable positive effect is cast iron of the following chemical composition, wt.%:

Carbon2.9-3.5

Silicon1.7-2.7

Manganese 0.3-0.8 Chrome 0.1-0.5

Nickel0.05-0.3

Vanadium 0.15-0.5 Titan 0.02-0.15

Nitrogen 0,005-0,03

Cerium0,005-0,02

Aluminum 0,001-0,1 Iron Others

Cast iron and a complex of elements (manganese, chromium, iron oxide, nickel, nitrogen) stabilizing and alloying the carbide phase of the iron, which ensures high mechanical properties of the material, h.

However, the use of known cast iron for the manufacture of cylinder liners of forced internal combustion engines is not advisable due to the lack of operational reliability of the friction pair. During the operation of forced carburettor engines, gases are generated as a result of the combustion of fuel, among which carbon dioxide and sulfur dioxide constitute a significant percentage. By combining with the condensate of water vapor, which is also contained in the combustion products, acids are formed and that interact with the metal surface and reduce the performance of the friction pair.

The aim of the invention is to increase the wear resistance in aggressive environments containing sulfur dioxide and carbon dioxide.

This goal is achieved by the fact that iron containing carbon, silicon, Mg, chromium, nickel, vanadium, nitrogen, titanium, rare earth metals, and iron, is additionally introduced to antimony n as follows; the ratio of ingredients May.%:

2.9-3.5

Carbon 1.7-2.7 Silicon 0.3-0.8 Manganese 0.1-0.3 Chromium 0.05-0.8 Nickel 0.15-0.5 Vanadium 0.005-0.02 Nitrogen 0.02 -0.15 Titanium Rare Earth Metals

(REM) 0.005-0.02

Antimony 0,005-0,3 Iron.

The presence of antimony cast iron in the composition leads to an increase in the dispersion and stability at high temperatures of the pearlitic structural component. The structure of cast iron consists of complex-alloyed chromium, nickel, vanadium, titanium, antimony perlite, small inclusions of graphite. The addition of antimony favorably affects the grinding of the primary structure, which is associated with an increase in the strength of the cast iron. In addition to introducing antimony into the melt before casting, it significantly reduces the influence of temperature and time conditions on the cast iron structure and makes it possible to obtain a pearlite metal base material and extend the temperature ranges for pouring and holding the metal in the ladle, provided by technical conditions of the melting process.

Doping of the metal base, increasing the dispersion of perlite and the uniform distribution of graphite will increase the wear resistance of cast iron in corrosive environments. The iron's tendency to adhesion is minimal. The increase in wear resistance in aggressive gaseous media is achieved when doping with antimony due to the complete elimination of microparts on the surface of the liner occupied by ferrite ..

In order to produce cast iron, three compositions of alloys are melted, containing ingredients at the lower, middle and upper levels. The iron content is additionally up to 100-0 in each alloy. For comparative tests, known cast iron with an average content of alloying elements was used. The chemical compositions of the studied cheuns are presented in table 1.

T

The content of components, wt.%

Alloy

With Si I Mn Frg I N1 TV T To JTi Fsb. TRME1 Se T

3.2 2.2 0.55 0.3 0.15 0.31 0.01 0.1

Famous Proposal2, 9 1.7 0.3 0.1 0.05 ems 1. 3.2 2.1 0.5 0.5 0.35 0.35 3.5 2.7 0.8 0.8 0.8 0.8

Cast iron is melted in a 40 kg crucible induction furnace with a kilo lining. Foundry iron brand LK-3, steel scrap, ferrous alloys of rare-earth metals (35% RZK), silicon (45% silicon), chromium (30% chromium), vanadium (45% vanadi), titanium (30% titanium, nitrided ferromanganese (5% nitrogen 75% manganese), crystalline antimony and nickel, antimony and RZK are introduced into the melt before pouring. The values of additives are calculated based on the average absorption of silicon, nickel, vanadium, antimony, manganese and chromium

Table 1

Fe

0.05 Remaining

at the level of 85-95%, titanium 70-80%,

REM 60-70%, - nitrogen 50-60% ..

Test specimens are cast in a dry mold. The wear resistance tests were carried out under conditions of dry friction sliding in tandem with improved steel 45 of hardness 48 HR, with a load of 15 kgf / mm and a sliding speed of 2.0 m / s, on an MT-2 friction machine in an atmosphere of 30 and CO2. Wear is estimated in grams reduced to a 1000 m path of relative movement of the sample along the surface of the counterbody. The obtained results are presented

in table.2.

I

Table 2 0.15 0.0050.02 0.0050.005 0, 28 0.01 0.1 0.2 0.09 -, 5 0.02 0.15 0.3 0.02 -

Famous

As can be seen from Table 2, the additional introduction of antimony in the indicated concentrations increases the wear resistance of the material in aggressive media. At the same time, the material has an optimal hardness, which allows machining of castings without changing the process.

The structure of the metal base of the proposed iron pearlite with evenly distributed inclusions of medium-sized graphite. High

1.22

62

227

the degree of dispersion of perlite and its complex doping, the presence

5 dispersed carbonitrides V, Ti provide good performance properties of a pair of friction in particularly difficult working conditions.

The limits of the content of components

0 established on the basis of obtaining a favorable combination of mechanical properties of wear resistance and corrosion resistance of cast iron. An increase in the concentration of antimony above 0.3% at-about leads to the appearance of ledeburite in the structure, which complicates the mechanical processing of the casting. The lower limit of 0.005% antimony ensures stable production of a pearlite matrix of cast irons with different carbon and silicon contents 1.7%). The minimum carbon content (2.9%) and silicon (1.7%) is caused by the need to obtain a metal matrix without a metastable phase. Maximum (3.5 and 2.7%, respectively) production of a pearlite structure with an amount of ferrite of no more than 10%. The chromium content (o, 1–0.8%) is nickel 0.05–0.5%), vanadium. (0.15-0.5%), titanium To, 08-0.15}, nitrogen (0.0050, 02%), is selected from the condition of maximum hardening of the metal base. An increase in the concentration of elements above the upper limit increases the tendency of the pig iron to chill. The limits of the content of rare-earth metals (0.005-0.0 provide for obtaining castings without chilling and REM. The proposed cast iron is most efficiently used for the manufacture of castings of cylinder liners of internal combustion engines. The economic effect of the application will be 700 thousand rubles per year.

Claims (1)

CAST IRON containing carbon, silicon, manganese, chromium, nickel, vanadium, nitrogen, titanium, rare earth metals and iron, different. the fact that, in order to increase wear resistance in an aggressive environment containing sulfur dioxide and carbon dioxide, it additionally contains antimony in the following Wearing ingredients, wt.%: Carbon 2.9-3.5 Silicon 1.7-2.7 Manganese 0 ‘, 3-0.8 Chromium 0.1-0.8 Nickel 0.05-0.8 Vanadium 0.15-0.5 about Nitrogen 0.005-0.02 and * S Titanium 0.02-0.15 Rare earth (L metals 0.005-0.02 Antimony 0.005-0.3 Cz Iron Rest - ·> about to go with © SI>