SU1696562A1 - Cast iron - Google Patents

Abstract

The invention relates to metallurgy. The goal is to increase wear resistance, specific tightness and contact endurance. Cast iron contains niobium and titanium in the following ratio of components, wt.%: Carbon 3.1-4.0; silicon 0.8-3.0; manganese 0.5-1.5; chromium 0.03-0.39; nickel 0.05-1.10; copper 0.02-0.90; phosphorus 0.15-0.90; niobium 0.05-0.60; titanium 0.05-0.36 and iron else. Contact endurance is 782-820 MPa. 2 tab.

Description

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The invention relates to metallurgy, in particular to the development of cast iron compositions for parts operating under conditions of friction and wear.

The purpose of the invention is to increase wear resistance, specific tightness and contact endurance.

The choice of the content of the boundary limits of the components in the cast iron of the proposed composition is due to the following.

Additional introduction of titanium increases the content of carbides in cast iron, hardness, specific tightness, crushes the structure of the alloyed matrix, which increases the density, strength and contact endurance. When the content of titanium is up to 0.05 wt.%, The increase of these characteristics is insufficient, and with an increase in the titanium concentration of more than 0.36 wt.%, The duration of isothermal exposure lengthens during the heat treatment of cast iron, specific tightness, durability and elastoplastic properties.

The microalloying of cast iron with chromium is caused by the grinding of the austenitic-bainitic structure, the increase in its density and stability, which contributes to an increase in the mechanical properties and contact endurance. Its effect begins to affect from a concentration of 0.03 wt.%, And with an increase in its content of more than 0.39 wt.%, The heterogeneity of the structure and hardness, the concentration of non-metallic inclusions along the grain boundaries, the specific tightness, elastic-plastic properties and strength decrease.

Additional introduction of niobium due to its high micro-doping ability while maintaining specific

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Hermetic and frictional properties, increased strength, contact endurance and plastic properties. The lower limit of its concentration is 0.05 wt.% Due to insufficient micro-alloying capacity at lower concentrations, which reduces contact endurance, strength and friction properties. With an increase in the niobium content of more than 0.6 wt.%, The concentration of 10 perlite in the pig iron increases and the specific tightness, strength and operational durability decrease.

Carbon and silicon are the main elements that determine the structure, specific tightness and complex properties of cast iron for various purposes, including its work in conditions of high contact loads and intense wear. With a carbon concentration of 3.1–4.0–20 wt.% And silicon of 0.8–3.0 wt.%, The most favorable conditions are created for the formation of a fine-grained austenitic-bainite structure, which is most favorable for ensuring high contact endurance , increase of density, specific tightness and elastic-plastic properties. When the concentration of carbon is up to 3.1 wt.% And silicon to 0.8 wt.%, The cement content increases and the amount of bainite decreases, the iron becomes less prone to bainitic transformation, the viscosity decreases, and the contact endurance decreases. With an increase in carbon concentration of more than 4.0 May,% 35 and silicon over 3.0 wt.% Density decreases, specific tightness, wear resistance, contact endurance and at the same time the number and size of graphite inclusions, 40

The concentration of the alloying components (phosphorus 0.15-0.9, nickel 0.05-1.1, copper 0.02-0.9, manganese 0.05-0.15, and chromium 0.03-0.39 wt. %) provides high strength characteristics, specific tightness, increased frictional wear resistance and contact

endurance. With an increase in their concentration above the upper limits, the liquation processes increase, the austenite content in the cast iron structure increases, which increases the tendency to embrittlement, reduces the specific tightness and elastic properties, while the concentration of these alloying elements decreases below the lower limits cast iron are insufficient.

The smelting of phosphorous chugues is carried out in open electric furnaces.

The alloying elements are added to a dispensing or pouring ladle before discharging the melt with a temperature of 1460-1470 ° C from the melting furnace. The melt is poured at 1400-1380 ° C in dry forms to obtain castings and process samples. The castings are heat treated with isothermal aging at 370-410 ° C for 1.1-2 hours.

In tab. 1 shows the chemical compositions of the investigated cast iron, and table. 2 - the results of their comparative tests.

Studies of the dispersion of cast iron and toughness are carried out according to GOST,

As can be seen from the table, 2, the proposed phosphorous cast iron has a higher operational resistance, providing an increase in specific tightness and contact endurance.

Claims (1)

Claims of iron containing carbon, silicon, manganese, chromium, nickel, copper, phosphorus and iron, characterized in that, in order to increase wear resistance, specific tightness and contact endurance, it additionally contains niobium and titanium in the following ratio of components, wt. %: carbon 3.1-4.0; silicon 0.8-3.0; manganese 0.5-1.5; chromium 0.03-0.39; nickel 0.05-1.1; copper 0.02-0.9; phosphorus 0.15-0.9; niobium 0.05-0.6; titanium 0.05-0.36; iron else. Table 1 table 2