SU1475961A1 - Cast iron with spherical graphite - Google Patents

Abstract

The invention relates to metallurgy and can be used in the manufacture of traverses for passenger-and-freight lifts. The purpose of the invention is to increase the tensile strength and improve wear resistance while maintaining the level of hardness and coefficient of friction. New cast iron contains components in the following ratio, wt.%: C 2.3-3.0

SI 0.1-0.5

MN 0.3-0.6

P 0.8-1.5

MG 0.03-0.1

CA 0,005-0,05

REM 0.03-0.5

AL 1.75-2.5

SN 0.08-0.14 and FE the rest. An additional input of the iron AL and SN, as well as reducing the content therein SI allowed to increase _in a σ 2.18-2.35 times, improved wear resistance by 2,42-2,72 times and maintain levels of hardness and coefficient of friction . 1 tab.

Description

one

The invention relates to metallurgy, in particular to the development of cast iron compositions primarily for the manufacture of traction shears for passenger-and-freight elevators.

The purpose of the invention is to increase the tensile strength of cast iron during stretching and improve wear resistance while maintaining the level of hardness and friction coefficient.

The choice of the boundary limits for the content of components included in the composition of the pig iron of the proposed composition is determined by the following.

The introduction of tin less than 0.08% does not allow to increase the hardness to the optimum value, with an increase in the addition of tin more than 0.14%, the strength decreases with a continuous increase in hardness. Tin addition improves casting properties.

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cast iron (increase fluidity and reduce linear shrinkage), and with the introduction of 0.005-0.05% calcium, in this case, high mechanical properties are achieved.

When the aluminum content is less than 1.75%, the fluidity is so small that it almost becomes impossible to obtain a solid casting.

When the aluminum content is more than 2.5% of the casting, they are affected by the films; interdendritic graphite appears in the structure, which impairs its strength characteristics.

When the aluminum content is within 1.75-2.5%, the castings are characterized by exceptional smoothness, purity, metallic gloss of the surface, the absence of roughness and

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burns, the absence of gas inclusions, have good machinability.

Increasing the silicon content by more than 0.5% leads to a decrease in strength and toughness, and the silicon content below 0.1% is determined by the technological possibilities of smelting (it is practically impossible to obtain charge materials with a lower silicon content). The absence of silicon and its replacement with aluminum is fully permitted.

When the phosphorus content is in the range of 0.8-1.5%, the phosphide eutectic has the most favorable structure from the point of view of the operating conditions of the pulleys.

Due to the presence of iron phosphides and phosphates in the pulley, the surface layers of the pulley have high mobility, resistance to movement and elasticity, which provide high frictional properties and wear resistance with minimal wear of the ropes and the absence of welding and slipping of the ropes.

When the phosphorus content is less than 0.8%, the casting properties of cast iron are deteriorated, and cast iron has reduced frictional properties.

When the phosphorus content is more than 1.5%, the strength properties of the pig iron fall.

The proposed phosphorus content provides the phenomenon of self-phosphating of the pulley surface during its interaction with the rope, the continuous formation of iron and manganese phosphate in the process of oxidation of phosphorus, iron and manganese on the rubbed surface of the pig iron.

The content of rare-earth materials (REM) in an amount of 0.03-0.5% suppresses the demodifying effect of tin, aluminum and phosphorus. When the content of rare-earth metals is less than 0.03%, graphite has a lamellar and worm-like form; spherical graphite is not observed in the structure.

The magnesium content in the range of 0.03-0.1% in combination with the above content of rare-earth metals provides a spherical shape of graphite.

A carbon content of less than 2.3% results in an excessive increase in hardness, increased shrinkage, and a risk of occurrence in the structure of free cementite.

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The dimensional heterogeneity of spherical inclusions of graphite increases, which reduces its wear resistance.

A carbon content of more than 3.0% dramatically reduces the strength characteristics of cast iron (approximately 2 kg for every 0.1% of carbon in excess of 3%) due to the formation of vermicular graphite inclusions.

Smelting of the proposed cast iron produced in induction electric furnaces with the main lining.

At the bottom of the crucible 3, a carburizer was loaded (electrode coking was the best) and steel metal scrap in the form of a die cut, trimmed after stamping, etc. were loaded onto it.

When the content of silicon in this waste is more than 0.5%, the metallized iron ore pellets were added to the mixture in an amount that provides the specified silicon content. When the melt reached a temperature of 1470–1500 ° C, 2.0–2.5% of slag by weight of the liquid metal was induced into the melt mirror. Slag consists of 70% CaO and 30% CaFi. After the slag covers the metal mirror, heated aluminum ingots were placed in the bath. The furnace is turned on at full capacity and held for 10-15 minutes until the aluminum has completely dissolved.

It is allowed to use calcined aluminum chips instead of ingots.

After that, the furnace switches to the nominal mode and 0.10-0.15% REM is introduced into the melt in the form of an FSZORMZO alloy. The alloy is immersed in the melt by electromagnetic stirring. Then the slag is downloaded, and the metal is poured into a ladle, at the bottom of which 0.3-0.4% of granulated magnesium is laid, on top loaded with iron filings. When draining from the furnace, the metal is modified on the chute with 0.3-0.4% silico-calcium. The tin is loaded on the bottom of the ladle along with granular magnesium.

Chemical compositions and the level of properties of known and proposed cast iron are given in the table.

As follows from the table, the additional input of aluminum and tin into the cast iron and a decrease in the silicon content in it make it possible to increase

2.18-2.35 times, improve wear resistance 2.48-1.72 times while maintaining hardness and friction coefficient.

Claims (1)

Invention Formula Nodular cast iron containing carbon, silicon, manganese, phosphorus, magnesium, calcium, rare earth elements and iron, characterized in that, in order to increase tensile strength and improve wear resistance while maintaining the level of hardness and coefficient reni, it will supplement luminium and silt when the components are wired, Carbon Silicon Manganese Phosphorus Magnesium Calcium Rare earth items Aluminum Tin Iron Flax contains the following sootp. %: 2.3-3.0 0.1-0.5 0.3-0.6 0.8-1.5, 0.03-0, 1 0.005-0.05 0.03-0.5 1.75-2.5 0.08-0.14 Else Wear resistance is determined according to the test results of hakachosed lifting pulleys with a lifting capacity of 320 kg; per unit of measurement, the wear resistance of the traction pulley ne cast iron SCh 30 is adopted.