RU2297468C1 - Antifriction cast iron - Google Patents

Abstract

FIELD: ferrous metallurgy.

SUBSTANCE: invention relates to wear-resistant cast irons. Proposed antifriction cast iron comprises the following components, wt.-%: carbon, 2.8-3.6; silicon, 2.1-3.8; manganese, 0.7-1.2; aluminum, 0.01-0.03; chrome, 0.10-0.50; nickel, 0.08-0.60; calcium, 0.02-0.06; phosphorus, 0.12-0.45; antimony, 0.002-0.07, and iron, the balance. Proposed cast iron shows enhanced modulus of elasticity and stability of exploitation properties. Proposed wear-resistant cast iron can be used in making oil-thickening ring articles working under large specific pressures.

EFFECT: improved and valuable technical properties of cast iron.

2 tbl

Description

The invention relates to metallurgy, and in particular to wear-resistant cast irons for the manufacture of parts for oil seal rings operating at high specific pressures.

Known anti-friction cast iron (USSR AS No. 836185, C22C 37/00, 1981), containing, wt.%:

Carbon 3.0-3.4 Silicon 1.6-2.2 Manganese 0.005-0.04 Sulfur 0.1-0.2 Antimony 0.15-0.25 Iron Rest

The hardness of cast iron is 224-230 HB.

Known cast iron has high wear resistance, but insufficient plastic and antifriction properties.

Known anti-friction cast iron (Japanese Patent No. 58-171553, class C22C 37/10, 1983) of the following chemical composition, wt.%:

Carbon 2.5-3.8 Silicon 3.5-4.8 Manganese up to 1.0 Phosphorus up to 0.1 Sulfur up to 0.1 Molybdenum 0.5-2.0 Cerium 0.02-0.5 Iron Rest

Known cast iron has a ferritic structure and low wear resistance.

Closest to the proposed invention is antifriction cast iron (AS USSR No. 956595, class C22C 37/10, 1982) of the following chemical composition, wt.%:

Carbon 2.0-2.6 Silicon 3.2-4.4 Manganese 0.5-1.0 Antimony 0.01-0.08 Aluminum 0.01-0.1 Iron Rest

The microstructure of cast iron consists of perlite, point and finely dispersed graphite with an interdendritic arrangement. After heat treatment according to the regime: heating to a temperature of 950 ° С, holding, oil quenching, tempering at a temperature of 360 ° С, the microstructure of cast iron consists of lower bainite, finely needle martensite, point and finely dispersed graphite with an interdendrite arrangement. This anti-friction cast iron has the following properties:

Temporary resistance, MPa 270-330 Depreciation, mg / m ² * h: At + 20 ° С 0.087-0.135 At -20 ° C 0.192-0.274 Scoring load MPa, not less than: At + 20 ° С 3.4-3.8 At -20 ° C 1.7-2.6 Conditional elastic modulus, GPa 105-120 Residual oil deformation o-rings,% 7-9

The disadvantage of cast iron is the instability of technological and operational properties.

The objective of this technical solution is to increase the modulus of elasticity and stability of operational properties, as a result of which the wear resistance of the o-rings is increased.

The problem is solved: in cast iron containing carbon, silicon, manganese, aluminum, antimony and iron, chromium, nickel, calcium, phosphorus are additionally introduced in the following ratio of components, wt.%:

Carbon 2.8-3.6 Silicon 2.1-3.8 Manganese 0.7-1.2 Aluminum 0.01-0.03 Chromium 0.10-0.50 Nickel 0.08-0.60 Calcium 0.02-0.06 Phosphorus 0.12-0.45 Antimony 0.002-0.07 Iron Rest

Cast iron is smelted in the IST - 0.16 induction electric furnace with overheating of the melt to a temperature of 1440-1460 ° C and refinement of the chemical composition according to the main (carbon and silicon) and alloying (chromium, nickel, manganese) components. As charge materials, I use foundry and foundry cast iron, pig-iron and steel scrap, ferromanganese, silicocalcium, ferrochrome, ferrophosphorus, nickel refineries, antimony metal, ferroaluminium and ferrosilicon.

Microalloying with antimony, ferrochrome, nickel and ferromanganese is carried out in an electric furnace, and modification with silicocalcium and aluminum is carried out in casting ladles using exothermic tablets. The melt is poured into molds at a temperature of 1380-1330 ° C.

Table 1 shows the chemical compositions of cast irons of experimental swimming trunks.

Table 1 Element The chemical composition of cast irons, wt.% 1 (reference) 2 3 four 5 6 Carbon 2,5 2,8 3.4 3.6 2.6 3.8 Silicon 3.3 2.1 2.6 3.8 1,6 4.0 Manganese 0.9 0.7 1,0 1,2 0.5 1.3 Antimony 0.08 0.002 0.005 0,07 0.01 0.1 Aluminum 0,07 0.01 0.02 0,03 0.002 0.05 Calcium - 0.02 0.04 0.06 0.02 0.08 Nickel - 0.08 0.40 0.60 0.01 0.71 Chromium - 0.1 0.18 0.50 0.04 0.57 Phosphorus - 0.12 0.25 0.45 0.06 0.53 Iron Ost. Ost. Ost. Ost. Ost. Ost.

Table 2 shows the mechanical, technological and antifriction properties of cast iron of experimental melts.

table 2 Cast iron Hardness HRB Depreciation, mg / m ² * m Modulus of elasticity, GPa The load causing seizure, MPa Impact strength J / cm ² Residual strain,% Operational Resistance, h 1 (ex.) 98 0,092 118 3,5 thirty 8.6 1380 2 99 0,040 126 9.6 35 9.2 1730 3 106 0,034 132 10,2 38 9.7 1880 four 104 0,042 130 9.8 34 9.5 1792 5 98 0,078 120 4.6 31 8.7 1420 6 95 0,085 124 5.3 27 8.5 1580

Calcium in an amount of 0.02-0.06 wt.% Microalloys the matrix, improves the shape of graphite, cleans grain boundaries from non-metallic inclusions, increases the stability of the structure, friction coefficient and mechanical properties. When the calcium content is up to 0.02 wt.%, The microalloying effect is weak, a significant increase in the stability of the friction coefficient and mechanical properties is not achieved. The upper limit of calcium content is limited by a concentration of 0.06 wt.%, Above which the amount of non-metallic inclusions increases, because calcium does not completely dissolve in the metal base, which leads to a decrease in toughness and ductility.

Chromium in an amount of 0.10-0.50 wt.% Grinds the structure of the matrix in the molten state and after heat treatment increases the wear resistance and stability of mechanical and operational properties and the coefficient of friction. At a chromium concentration of up to 0.10 wt.%, Crushing of the structure and increase of wear resistance, stability of mechanical, technological and operational properties are insufficient, and at a concentration of more than 0.50 wt.%, Segregation processes increase, the heterogeneity of the structure increases, the stability of technological and antifriction properties of cast iron decreases .

Nickel in the amount of 0.08-0.60 wt.% Improves and stabilizes the structure and increases the technological and antifriction properties of cast iron in a wide temperature range. Nickel concentration is determined experimentally. With an increase in the nickel content of more than 0.60 wt.%, Metal waste increases, coagulation processes increase, and the content of nonmetallic inclusions along grain boundaries increases, which reduces the stability of plastic properties. When the nickel content is up to 0.08 wt.%, The stability of the antifriction properties is reduced.

Phosphorus crushes the structure of sorbitol-like perlite, forms a phosphide eutectic, and improves technological and operational properties. At a phosphorus concentration of up to 0.12 wt.%, Hardness, wear resistance, technological and operational properties are insufficient, and with an increase in phosphorus concentration of more than 0.45 wt.%, The uniformity of the phosphide eutectic and the structure of cast iron decreases, the stability of the technological and operational properties decreases.

The carbon content is adopted in accordance with the practice of producing cast iron with a uniform structure and a stable coefficient of friction, and the silicon concentration is limited to 2.1-3.8 wt.%. With an increase in silicon content of more than 3.8 wt.%, The dispersion of graphite decreases, cold resistance, friction coefficient, mechanical properties and their stability decrease. The manganese content in cast iron is increased to 0.7-1.2 wt.% To increase the plastic properties and reduce the friction coefficient, and aluminum is adopted in an amount of 0.01-0.03 wt.%, I.e. in an amount that does not reduce the plastic properties and has the necessary modifying effect, contributing to the refinement of the structure and stabilization of the friction coefficient.

Antimony microalloying in an amount of 0.002-0.07 wt.% Neutralizes impurities, grinds the structure and increases the stability of the friction coefficient and plastic properties over a wide temperature range. The upper limit of antimony is 0.07 wt.% Is limited by its low solubility in cast iron, and with a decrease of less than 0.002 wt.%, The wear of cast iron increases.

The fumes of microalloying additives amounted to: antimony - 26%, nickel - 14%, calcium - 32% and chromium - 10%.

The mechanical properties of cast irons were determined by standard samples after tempering at a temperature of 360 ° C for two hours.

As can be seen from table 2, the proposed cast iron has a higher level of mechanical, technological and antifriction properties and more stable characteristics of the coefficient of friction, wear resistance and extreme pressure properties than the basic antifriction cast iron.

The use of the proposed cast iron as a structural material for o-ring seals and for the production of parts experiencing high specific loads during operation significantly increases their operational reliability and makes it possible to replace cast steel billets with cast iron and reduce the complexity of manufacturing antifriction parts.

Claims (1)

Anti-friction cast iron containing carbon, silicon, manganese, aluminum, antimony and iron, characterized in that it additionally contains chromium, nickel, calcium and phosphorus in the following ratio, wt.%: Carbon 2.8-3.6 Silicon 2.1-3.8 Manganese 0.7-1.2 Aluminum 0.01-0.03 Chromium 0.10-0.50 Nickel 0.08-0.60 Calcium 0.02-0.06 Phosphorus 0.12-0.45 Antimony 0.002-0.07 Iron Rest