RU1813115C - Alloy for wear-resistant surfacing - Google Patents

Abstract

The invention relates to metallurgy, in particular to electroslag casting or surfacing of parts. SUMMARY OF THE INVENTION: to increase strength, wear resistance and cold resistance, an alloy for wear-resistant surfacing containing carbon, chromium, manganese, silicon, nickel, nitrogen additionally contains vanadium in the following ratio, wt%: carbon 3.2-4.5; chrome 22-28; manganese 1.5-2.0; silicon 1.0-1.5; nitrogen 0.05-0.01; vanadium 1.5-2.0; nickel 0.2-0.6; iron the rest. 2 tab.

Description

The invention relates to metallurgy, in particular to electroslag casting or surfacing of parts, and consists in the development of an alloy providing high service properties of parts, for example, teeth of excavator buckets, under conditions of shock-abrasive wear at positive and negative temperatures.

The purpose of the invention is to improve the cold resistance of the alloy.

This goal is achieved by the fact that in cast iron containing carbon, chromium, manganese, silicon, nickel and nitrogen, vanadium is additionally introduced in the following ratio of components,%:

Carbon 3.2-4.4 Chromium 22.0-28.0. Manganese 1.5-2.0 Silicon 1.0-1.5 Vanadium 1.5-2.0 Nitrogen 0.05-0.1

Nickel 0.2-0.6 Iron Else Parts operating in the northern regions have a low service life, which is explained by embrittlement of the metal at low temperatures, i.e. their insufficient cold resistance. Embrittlement of iron-carbon alloys at lower temperatures is associated with phase transformations in which primary and eutectic austenite transforms into martensite. Therefore, in order to ensure high properties of the alloys at low temperatures or cold resistance, it is necessary that the austenitic structure of these alloys have increased resistance to decomposition with the formation of martensite. This can be achieved by rationally alloying the alloy.

Manganese is a fairly strong austenite-forming element. At

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holding less than 1.5% Mn there is no noticeable change in the structure and properties of the alloys. In fact, this is the amount of Mn that is introduced using the charge materials. In an amount of from 1.5 to 2%, the Mgzgene stabilizes the γ phase, increasing the cold resistance of the alloy. At a concentration of more than 2% Mn, the properties of alloys deteriorate both at positive and negative temperatures, which is associated with the formation of a coarse coarse-grained structure under the influence of manganese.

The stronger austenitic element is Ni.

A content of less than 0.2% Ni is ineffective, and more than 0.6% Ml leads to a noticeable rise in price of the alloy. The concentration of NI is 0.2-0.6 in combination with 1.5-2.0% Mp, is the most rational, increasing stability of the γ phase. The absence of martensite in the base of the alloy favorably affects its strength. Austenitic alloyed with Ni reliably fixes the carbide phase, preventing it from spalling, which leads to an increase in the wear resistance of the alloy. The absence of conversion of austenite to martensite upon cooling of the alloy below 0 ° C helps to maintain high strength and wear resistance at low temperatures.

Nitrogen, which is part of the proposed alloy, not only forms nitrides and carbonitrides, but increases the stability of austenite against decomposition, i.e. in the same way as Mn and No., it contributes to the preservation of high properties of the alloys when the temperature drops below 0 ° C. At a content of less than 0.05%, nitrogen is almost completely spent on the formation of hardening phases. In a concentration range of 0.05-0.1%, nitrogen is distributed between carbonitrides and solid solution, increasing the stability of the latter. At a content of more than 0.1% N, a large amount of carbonitride Li is formed, tearing during the wear process, do not contribute to an increase in the wear resistance and strength of the alloy at positive and negative temperatures.

Vanadium is a strong carbide and nitride forming element. The hardening phases vanadium formed along with carbon and nitrogen increase the wear resistance of the alloys. Carbides and carbonitrides, separated from a liquid solution and being centers of crystallization, contribute to a decrease in the structure, which in turn has a positive effect on the strength

alloy. The number of hardening phases depends on the content of V; A content of less than 1.5% V is ineffective due to the insufficient number of hardening phases. The introduction of more than 2% V is impractical due to the formation of a large number of chemical compounds of vanadium, which can lead to an increase in hardness and embrittlement of the alloy, as well as to a significant increase in its cost.

Unlike titanium, vanadium not only forms hardening phases, but also alloys the alloy base, increasing its resistance to decomposition at negative temperatures, i.e. increasing the cold resistance of the alloy. With the introduction of more than 2% vanadium, the resulting large number of vanadium chemical compounds depletes eutectic austenite, decreases its stability when the temperature drops below 0 ° C. At a content of less than 1.5% vanadium, the resulting number of hardening phases is insufficient to provide good resistance figurative impact.

Carbon and chromium are the main elements forming the alloy structure. The amount and type of excreted carbi depends on the content of these elements. Dov. With a content of 3.2-4.5% C and 22-28% Cg, mainly trigonal carbides MtCz and are formed. in a small amount of MZS carbides. With a content of less than 3.2% C4 less than 22% Cg, the amount of cementite type carbides increases, which leads to a decrease in resistance to abrasive action. Above 4.5% C and 28% Cr, a large amount of trigonal chromium carbides is formed. This is accompanied by lean days, lowering the base of the alloy with carbon and chromium, and a decrease in its stability, especially at low temperatures, i.e. such an alloy is characterized by low cold resistance and low strength. .

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Example, Alloys of the proposed and non-natural composition were melted in an induction furnace with a crucible capacity of 50 kg. In this case, plate electrodes with a size of 15x90x400 m were obtained, m - Plate electrodes were subjected to electroslag remelting in a copper water-cooled mold of 60x40x100 mm.,.

Samples were cut from ingots to determine wear and bending strength at positive and negative temperatures.

Table 1 shows the chemical composition of the studied alloys, table 2 shows the mechanical properties,

It can be seen from Table 2 that the alloy of the proposed composition has higher wear resistance in the entire range of element concentrations, which is explained by the presence of finely dispersed vanadium carbonitrides in its structure, which are firmly fixed in the austenitic matrix, which does not undergo phase transformations upon cooling of the alloy. The finely dispersed structure along with a stable austenitic structure makes it possible to increase the strength of the proposed alloy both at positive and negative temperatures or its coldness.

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Claims (1)

The claims An alloy for wear-resistant surfacing containing carbon, chromium, manganese, silicon, nickel, nitrogen and iron, characterized in that, in order to increase the cold resistance, it additionally contains vanadium in the following ratio of components, wt.%: Carbon 3.2-4.5 Chromium 22-28 Manganese. 1.5-2.0 Silicon 1.0-1.5 Nickel 0.2-0.6 Nitrogen 0.05-0.10 Vanadium 1.5-2.0 Iron The rest. The chemical composition of the studied alloys after electroslag remelting Table 2 Mechanical properties of alloys after electroslag remelting Table 1 Table 2 (continued)