SU1765238A1 - Wear-resistant cast iron - Google Patents

Abstract

High-strength heat-resistant cast iron belongs to the field of metallurgy. The invention: high-strength cast iron additionally contains antimony, titanium, cerium, boron, nitrogen and bismuth in the following ratio of components, wt.%: Carbon 2.7-3.1; silicon 2.2-2.6; manganese 0.2-0.7; nickel 0.4-0.8; copper 0.8-1.6. molybdenum 1.2-1.8, vanadium 0.2-0.8; aluminum 0.02-0.07; magnesium 0.03-0.07; tin 0.002-0.01; chromium 0.02-0.06; boron 0.002-0.005, cerium 0.02-0.06; calcium 0,002-0,015; antimony 0.02-0.06: nitrogen 0.04-0.11; titanium 0.02-0.07; bismuth 0.002-0.004 and iron - the rest. Resistance to thermal shock is 3870-4080 cycles. 2 tab.

Description

The invention relates to the field of metallurgy, in particular to wear-resistant pig iron, operating under conditions of corrosion-mechanical wear. Known wear-resistant cast iron containing, by weight.%:

carbon2-2.5

silicon2.5-3.5

manganese8.0-10

iron ostal

Known cast iron has insufficient corrosion and corrosion resistance.

Also known wear-resistant cast iron of the following chemical composition, wt.%: Carbon2,51-3.80

silicon 1,35-2,49

manganese 0.40-1.28

chromium 0.35-1.95

copper 0.11-1.49

metals from the group containing calcium, titanium, boron, aluminum, antimony, tellurium in the amount of 0.25-1.20

iron ostal

The closest to the proposed is cast iron containing, in wt.%: Carbon2.8-3.6

silicon 1,5-2,3

manganese8.0-10

aluminum0.4-0.8

copper 0.8-2.5

chrome 0.08-0.5

РЗМ0,01-0,1

iron ostal

The corrosion rate of known iron in circulating water at 5-8.2 is 0.040-0.048 g / m2 h. The coefficient of relative wear resistance when tested in a mixture of quartzite and reverse water is 1.54– 1.80. Operational stability - up to 1000 h.

The disadvantage of the known cast iron - low wear resistance in a hydroabrasive environment.

The purpose of the invention is to increase the wear resistance and operational durability.

four

DS

SL

hO

with

00

The goal is achieved by the fact that the iron additionally contains boron, titanium, chromium nitrides and calcium in the following ratio of components, wt.%: Carbon2.6-3.6

silicon1,6-2,3

manganese9,1-11,5

aluminum0.05-0.75

copper 0,81-2,88

rare earth

metals0.002-0.05

bor0.04-0.12

chromium nitride 0.03-0.31

titanium0.003-0.16

calcium0,002-0,028

iron ostal

Significant differences of the proposed technical solution are the introduction of micro-alloying additives: boron 0.04-0.12 wt.%, Chromium nitrides 0.03-0.31 and titanium 0.003-0.16 wt.% And additional modification with calcium, which significantly increases wear resistance and service resistance while retaining technological properties, non-magnetic and corrosion resistance.

An analysis of the proposed technical solution showed that at the moment there are no technical solutions that would reflect these differences. In addition, these signs are necessary and sufficient to achieve a positive effect. This leads to the conclusion that these differences are significant.

Boron at a content of 0.05–0.3 wt.% Stabilizes perlite, increases its spheroidization, increases hardness and wear resistance, their stability during operation and the operational durability of cast parts. With an increase in boron concentration of more than 0.12 wt.%, Its segregation begins to appear, the form factor of graphite decreases, and at a concentration of up to 0.04 wt.%, The hardness and wear resistance of castings decrease, plastic perlite with a dispersity of 1.0 predominates in castings. -Pd 1.4 (according to GOST 3443-87), which reduces wear resistance and performance properties.

The introduction of chromium nitrides in the amount of 0.03-0.31 May. % crushes the structure of perlite, graphite inclusions, increases hardness, wear resistance, tightness and operational durability. With a concentration of up to 0.03 wt.% Wear resistance, dispersion of the structure and operational durability are insufficient, and with a concentration of chromium nitrides more

0.31 wt.% Structure heterogeneity increases, graphite shape factor decreases, impact fatigue and performance properties.

Rare earth metals in quantities

0.002-0.5 wt.% In the proposed cast iron, as in the well-known, provides for the degassing of the melt, the spheroidization of graphite and increases the hardness, wear resistance and performance properties. With an increase in their concentration of more than 0.05% by weight, the homogeneity of the structure, the stability of the endurance limit, impact strength, wear resistance and performance properties decrease.

5 Additional introduction of titanium in the amount of 0.003-0.16 wt.% Crushes the structure of cast iron in the castings, increases the corrosion resistance, the form factor of graphite and provides increased wear resistance and operating life. At a concentration of up to 0.003 wt.%, The dispersion and stability of the structure, wear resistance and hardness are insufficient, and at a concentration of titanium of more than 0.16 wt.%, The technological properties and operational properties are reduced under conditions of impact abrasive wear.

The introduction of calcium contributes to the cleaning of the grain boundaries and the spheroidization of graphite.

0 When calcium concentration is up to 0.002 wt.%, Dispersion of graphite, mechanical and operational properties decrease. When the calcium concentration is more than 0.028 wt.%, The stability of the structure decreases and

5 properties, durability, fatigue life and service resistance are reduced.

Copper in the amount of 0.81-2.88 wt.% As an effective additive strengthens the metal base and does not reduce the viscosity of cast iron, reduces porosal brittleness and the tendency of cast iron to form cracks, increases wear resistance and operational durability. When copper concentration is less than

5 0.81 wt.% Its effect is negligible. Increasing its concentration by more than 2.88 wt.% Increases liquation, reduces the shape factor of graphite and structure homogeneity, wear resistance and operational length.

The carbon and silicon content in the proposed cast iron was chosen taking into account the practice of producing wear-resistant castings with increased values of hardness, corrosion resistance and operational durability. With an increase in their concentration above the upper limits, the stability of the structure in toughness and the characteristics of wear resistance and elastic-plastic properties decrease, while

by decreasing the concentration of less than the lower limits, the fluidity decreases, eutectic cementite is released, and chill is increased, which leads to a decrease in crack resistance, plastic properties and operational durability.

Aluminum has a deoxidizing, micro-alloying and stabilizing effect, contributing to a reduction in the content of non-metallic inclusions and an increase in hardness and wear resistance. At a concentration of up to 0.05 wt.%, The deoxidizing, microalloying and stabilizing effect thereof is insufficient, and at an aluminum concentration of more than 0.75 wt.%, The hardness of the castings decrease, the relative wear resistance and operational durability.

The manganese content is increased to 9.1-11.5 wt.% And is limited by the concentration limits below which the perlite and the high spheroidization of perlite do not reach and the wear resistance is significantly increased, and the content of cementite and chill increases above the upper limit, the fragility increases. ry and plastic properties, impact fatigue durability and operational durability under conditions of impact abrasive wear.

Experimental smelting of high-strength cast irons is carried out in arc furnaces. Overheating of the melt during melting is 1490-1510 ° C. Cast iron, scrap iron 17A, steel scrap 1A, ferromanganese FMp75, ferroor FB2 (GOST 14848-69) FSZORZMZO alloy (TU 14-5-136-81), chromium nitrides (TU 6-09- 0345-75), ferrotitanium FTiZO (GOST 4761-80), silicocalcium FSK16A2, copper M, titanium-bearing iron and ferrosilicon. Melt refining is produced by soda ash (GOST 5100-73). The microalloying of the melt by ferroboron and ferrotitanium is carried out in an electric furnace at the end of the melt, and

The formation of silicocalcium, FSFORZM20 alloy and chromium nitrides in casting ladles.

Wear-resistant castings, process samples and samples for mechanical testing are cast from modified cast irons.

The determination of the content of components in the cast iron was carried out by methods of differential chemical analysis. Impact strength is determined on samples of 10 x 10 x 55 mm with a Y-shaped notch.

Mechanical tests are carried out by standard methods, and analysis of the structure of cast iron according to GOST 3443-87. The operational reliability is determined on dry friction test benches, paired with syntegran.

The proposed cast iron provides higher wear resistance, hardness and operational resistance than the base cast iron.

Claims (1)

Claims of wear-resistant cast iron containing carbon, silicon, manganese, copper, aluminum, rare earth metals and iron, characterized in that, in order to increase wear resistance and service resistance, it additionally contains boron, titanium, calcium and chromium nitrides in the following ratio of components, May %: Carbon Silicon Manganese Aluminum Copper Rare earth metals Boron Chromium nitride Titanium Calcium Iron 2.6-3.6 1.6-2.3 9.1-11.5 0.05-0.75 0.81-2.88 0.002-0.05 0.04-0.12 0.03-0.31 0.003-0.16 0.002-0.028 Rest