SU1705392A1 - Cask iron - Google Patents

Abstract

The invention relates to metallurgy and can be used in the production of iron castings. The purpose of the invention is to increase the contact endurance and impact fatigue life. The proposed cast iron, contains, wt%: C 2.1-2.6; Si 0.7-1.6; Mp 0.6-1.8; Cr 0.7-1.6; Ni 2.1-2.9} Cu 0.2-1.5; P 0.2-0.7; But 2.05-3.3; Nb 0.03-0.6; titanium nitrides 0.02-0.3; B 0.12-0.33; Zr 0.03-0.6; Ce 0.03-0.08; Fe rest. Additional input into the composition of the proposed Nb cast iron of tyrants nitrides, B, Zr, and Ce allows an increase in the contact tolerance of 1.09-1.1 & times and impact fatigue life 1.2-1.3 times. 2 tab. z ten

Description

The invention relates to metallurgy. In particular, to phosphorous cast irons with increased contact endurance.

Known cast iron containing, by weight. Carbon dioxide 2.8-1, 2 Silicon 2j0-3.8 Manganese 0.1-1.0 Antimony 0.07-1.0 Phosphorus 0.001-0.3 Sulfur 0.001-0.1 Iron Remaining The depth of chill cast iron 1 mm . Contact endurance is low.

Known phosphorous cast iron of the following chemical composition, wt. $: Carbon 2.8-3.2 Silicon 1.2-1.7 Phosphorus 0.2-0.6 Chromium 0.2-0.6

Manganese Up to 1.0 Sulfur To 0.1 Iron Else This cast iron has a coarse-grained

structure and unstable mechanical

properties.

Closest to the proposed

is the following chemical cast iron

composition, wt.%: Carbon Silicon Manganese Chrome

Nickel

Phosphorus

Copper

Molybdenum

Iron

2.7-3.1. 0.3-0.6 0.6-1.0 0.7-1.0 2..2-3.0

0.3-0.5 0.8-2.0

0.3-0.6 Else

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The hardness of cast iron, LDC, and wear - 0.387-0.1 g. In the manufacture

rolls and other tooling parts, there are insufficient characteristics of hardness, brittle strength and contact endurance. With optimal chemical composition, contact endurance does not exceed 50-520 MPa.

The purpose of the invention is to increase the contact endurance and impact-fatigue durability.

The goal is achieved by the fact that phosphorus iron containing carbon, silicon, manganese, chromium, nickel, copper, molybdenum and iron, additionally contains zirconium, niobium, titanium nitrides, boron and cerium in the following ratio of components,% by weight:

Carbon2.1-2.6 Silicon 0.7-1.6 Manganese 0.6-1.8 Chromium 0.7-1.6 Nickel 2.1-2.9 Copper 0.2-1.5 Phosphorus 0, 2-0.7 Molybdenum 2.05-3.3 Niobium. 0.2-1.2 Titanium nitride 0.02-0.3 Boron 0.12-0.33 Cerium 0.03-0.08 Zirconium 0.03-0.6 Iron Rest The addition of titanium nitrides to the cast iron has a modifying effect. impact, increases the dispersion of the structure and impact fatigue life.

With an increase in their concentration over the upper limits, the heterogeneity of the structure increases, the content of non-metallic inclusions along the grain boundary and the mechanical properties and heat resistance decrease. At a concentration of less than 0.02 masD, the impact-fatigue durability and mechanical properties are insufficient.

The content of carbon, manganese and silicon is based on the experience in the production of phosphorous iron for critical castings, operating under thermal shock and high temperature conditions. The upper concentrations of carbon and silicon are limited to the content that eliminates the formation of free graphite in the castings and provide enhanced plastic properties at elevated temperatures. With increasing concentration

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Trace manganese over the upper limit increases the amount of austenite and perlite and decreases the plastic properties of cast iron. By reducing their concentration to less than the lower limits, the contamination of the metal with sulfur and other non-metallic inclusions increases and the stability of the structure and mechanical properties decrease, and the tendency of the metal to brittle fracture and cracks during thermal cycling increases.

Copper crushes the structure, improving technological properties and impact-fatigue life, but at a concentration of not more than 1.5% by weight, lycolcil increases and properties decrease.

Boron is introduced to improve the uniformity and stability of the cast iron structure in castings, to refine the structure and to improve the plastic and operational properties at high temperatures. The lower limit of the boron concentration is taken from the content (0.12 masD) at which a noticeable increase in thermal stability and plastic properties is observed, and is limited by the concentration (0.33 mas mas), above which the content of non-metallic inclusions at the grain boundaries increases, which reduces the impact strength , shock resistance and impact fatigue life.

The introduction of cerium stabilizes the process of modification and increases the homogeneity of cast iron in thick-walled castings, crushes the structure and improves the mechanical properties and technological plasticity. With a concentration of up to 0.03 May. the homogeneity of cast iron in thick-walled castings and its technological and mechanical properties are insufficient, and at a concentration of more than 0.08 masst, the elastic-plastic properties, crack resistance, technological plasticity and impact fatigue durability are reduced.

Nickel dopes the matrix, increases the strength, density, dispersion and uniformity of the structure, technological and plastic properties in castings, which ensures the stability of the elastic-plastic and operational properties. At a concentration of up to 2.1 May.% Alloying effect on the article. structure and mechanical properties are weak, and

By increasing the nickel content to more than 2.9 wt%, the impact resistance and mechanical ductility and durability are reduced.

Zirconium is introduced into high-strength cast iron to reduce microporosity, increase the stability of the structure in thick-walled castings, mechanical,

service and technological properties. At a concentration of up to 0.03 mass%, the uniformity and dispersion of the cast iron structure in castings and the mechanical properties are insufficient, and with an increase in contact endurance and impact, a decrease in the technological plasticity and resistance of the cast iron under conditions of shock load, fluidity, crackness, leads to a decrease in operational durability of parts.

The addition of zirconium stabilizes the dispersion of the structure, increasing the impact strength, impact strength and contact endurance. Its content begins to affect from a concentration of 0.03 wt.%, But with an increase in its content of more than 0.6 wt.%, The concentration of non-metallic inclusions at the grain boundaries increases and the mechanical and operational properties of cast iron decrease.

Chromium is introduced as a surfactant additive that enhances the stability of the effect of doping with titanium nitrides. When its content is up to 0.7 wt.%, The effect is insignificant, and with an increase in the content of more than 1.6 masD, the stability of the structure decreases, the shape of graphite and technological properties deteriorate, and the process of obtaining the specified structure and properties becomes complicated.

Microalloying with niobium in the amount of 0.2-1.2 May.2; increases crack resistance and mechanical strength, contributes to the improvement of plastic properties at high temperatures. At a concentration of less than 0.2% by mass, its effect is insignificant, and at a concentration of more than 1.2% by weight, the stability of the structure, mechanical properties, especially at elevated temperatures, and impact-fatigue durability decrease.

Example. Experimental melting of cast iron with a hypoeutectic composition was performed

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Vagrankle duplex process - electric arc. As the charge materials, limiting coke iron, steel scrap, ferrovanadium, Ferromanganese, ferroniobium, ferromolybdenum and other ferroalloys were used. With the release of iron from the cupola, the metal temperature was JOO-1 20 ° C. Overheating of the melt in an electric arc furnace - Y80-1500 C.

Additive of ferromolybdenum FMO2, ferrochrome FHbOO, nickel, ferroniobi

FN 660 and ferromanganese FMN75 (GOST) were produced in an electric furnace, ferrozirconium, ferrosiliconiobium FSNBZO (TU Y-1M-90-86) and copper M1 (GOST), ferrocerium and crushed nitride briquettes into the foundry buckets when they were melted from the furnace.

Titanium nitride was introduced into dispensing casting buckets with a capacity of 2 tons with, and ferrocerium - into casting buckets. Modified cast iron was poured to obtain process samples, 16 mm samples and castings of brackets, hubs and forks were made on a floor casting conveyor in wet sandy-clay molds. Filling temperature 1390-Y 10 C.

To obtain cast iron, the casting is heat treated using the first stage of graphitization at 960–980 ° C, and 5–2 stages at 660–680 ° C for 1.5 hours and isothermal aging at 370 ° IO ° C.

In tab. 1 shows the chemical composition of the cast iron; in tab. 2 - mechanical properties and impact fatigue durability.

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Claims (1)

Invention Formula Cast iron containing carbon, silicon, manganese, chromium, nickel, copper, phosphorus, molybdenum and iron, characterized in that, in order to increase contact endurance and impact fatigue life, it additionally contains niobium, titanium nitrides, boron, zirconium, and cerium in the following ratio of components, May.% :. Carbon2.1-2.6 Silicon 0.7-1.6 Manganese 0.6-1.8 Chromium 0.7-1.6 Nickel 2.1-2.9 Copper 0.2-1.5 Phosphorus Molybdenum Niobium Titanium Nitrides 7.8 8.5 8.2 6.6 5.9 0, 010 0.007 0.008 0.002 0.016 0.03 6, 5 10.2 12.5 12.2 12.1 9.2 7.5 650 712 758 661 635 1560 1620 1696 1635 JU 1020 7.8 8.5 8.2 6.6 5.9 0.007 0.008 0.002 0.016 0.03