SU1763507A1 - Alloy - Google Patents

Abstract

The invention relates to metallurgy, in particular to alloys for the manufacture of wear-resistant parts. The essence of the invention: the proposed alloy contains, May. %: carbon 1.38-1.9; silicon 0.32-0.9; manganese 1.85-3.2; chromium 3.8-5.5; vanadium 3.8-6.4; aluminum 0.02-0.06; iron - the rest. In the cast state, the hardness of the alloy is НRSe 58-61, the relative wear resistance under friction on corundum at a speed of 5 m / min with a load of 7 MPa is 3.4-4.4 compared to steel 45 (HB 200) is 12-35 J / cm. 1 tab.

Description

The invention relates to metallurgy, in particular to alloys for the manufacture of wear-resistant parts.

Known self-hardening white cast iron having an infused state of high hardness and wear resistance 1. Cast iron contains, May. %:

Carbon

Silicon

Manganese

Chromium

Titanium

Calcium

Iron

2.8-3.4

2.2-3.1

2.4-3.5

5.2-8.1

0.02-0.30

0,002-0,020

Rest

The cast hardness is HRC 58-61 with a relative wear resistance of 2.80-3.46 (the reference is steel 45 with hardness HB 200). The disadvantage of this cast iron is its low toughness (CS up to 3 J / cm2), which does not allow its use for the manufacture of parts operating under dynamic loading conditions.

The closest to the proposed is alloy 2, containing, May. %; Carbon 1,25-2,20

Molybdenum0,10-3,50

Chrome5.6-8.0

Vanadium4.3-7.6

Silicon1,4-2,6

Manganese 0.3-1.8

Aluminum0,1-0,5

REE0.02-0.15

IronErest

This alloy, after quenching and tempering, has high hardness, wear resistance and sufficient impact strength (with some combinations of elements, impact strength reaches 25 J / cm2). However, in the cast state, the hardness and wear resistance are significantly lower. For example, in blanks with a diameter of 20 mm, cast into a dry earth form, the hardness is HRC 53CO

WITH

i o

CJ

ate about vj

56. The disadvantage of the alloy is also high cost due to the presence of expensive and scarce molybdenum in the alloy.

The purpose of the invention is to increase in the cast state of hardness, wear resistance and toughness.

This goal is achieved in that the alloy containing carbon, chromium, vanadium, manganese, silicon, aluminum and iron contains them in the following ratio, May. %:

Carbon1.38-1.90

Silicon0.32-0.90

Manganese1.85-3.20

Chrome 3.80-5.50

Vanadium 3.80-6.40

Aluminum 0.02-0.06

IronErest

The composition of the alloy is selected based on the following considerations.

The chromium content is limited to the interval of 3.8-5.5%. When the chromium content goes below the lower limit, the austenite and martensite doping is insufficient and the total amount of carbides in the alloy decreases, which is manifested in a decrease in its hardenability, hardness and wear resistance. When the chromium content is more than 5.5%, the amount of triple euteutics increases, which leads to a decrease in the alloy toughness.

The vanadium content is recommended in the range of 3.8-6.4% (depending on the content of carbon and other elements). When the vanadium content is less than 3.8%, carbides appear in an appreciable amount in the alloy structure, which leads to a decrease in the strength and toughness of the alloy. A vanadium content of more than 6.4% is impractical for two reasons: firstly, to form a large amount of VC carbides, it decarburizes the solid solution and impairs the hardenability of the alloy; secondly, the high content of vanadium leads to an increase in the cost of the alloy.

The manganese content in the alloy should be not less than 1.85% to ensure the hardenability of thin-walled castings when they are cooled in a mold. The greater the wall thickness of the castings, the greater must be manganese in the alloy. For castings with a wall thickness of 30-40 mm, the manganese content in the alloy should be increased to 3.2%. A higher manganese content in the alloy is impractical because of the significant increase in the amount of residual austenite in the structure and the decrease in the hardness of the alloy.

Silicon in the amount of 0.90% increases the tendency of the alloy to carbide aging, which manifests itself in an increase in its hardness and wear resistance. With a higher silicon content (especially in combination with chromium and vanadium

at the upper level, the hardenability of the alloy is deteriorated due to the d-ferrite in its structure. At a content of 0.32%, silicon is a technical impurity, and its lesser content is almost negligible.

can be provided in the conditions of the foundry.

The proposed carbon content range (1.38-1.90%) ensures the formation of double eutectic colonies A + VC in the alloy structure (where A is austenite) with a noticeable composite strengthening effect. With a carbon content of less than 1.38%, double eutectic areas are episodic and have little effect on the overall level of hardness and wear resistance of the alloy. A carbon content of more than 1.9% is impractical because it requires too high a vanadium content, leading to

an increase in total carbides and a decrease in alloy toughness.

Aluminum is introduced at the final stage of smelting in a small amount (providing a residual content of 0.020, 06%) in order to partially deoxidize vanadium-containing slag and reduce vanadium carbon monoxide.

Sulfur (up to 0.05%) and phosphorus may be present as impurities in the alloy.

(up to 0.08%).

Melting was carried out in an induction crucible furnace IST-0.06. Liquid metal casting in dry sandy-clay forms. Cast billets in the form of bars with a section of 15x15 and 30x30 mm. Samples for impact bending, hardness and wear resistance were produced from the bars. Tests for wear were carried out by friction on an abrasive belt (from corundum pelts) with

the speed of the last 5 m / min and a specific load of 7 MPa. Wear was determined by weight loss during friction. The relative wear resistance was evaluated by the coefficient

to U3

where Ua and im are the wear values of the standard (steel 45 with HB 200) and the test material, respectively.

Compared with prototype 2, the proposed alloy has reduced chromium, silicon and aluminum contents, eliminated mo

Claims (1)

Claim An alloy containing carbon, silicon, manganese, chromium, vanadium, aluminum, and iron is characterized in that, in order to increase the hardness of the wear resistance and toughness in lithium, it contains components in the following ratio, May. %: Carbon 1.38-1.9 Silicon 0.32-0.9 Manganese 1.85-3.2 Chromium 3.8-5.5 Vanadium 3.8-6.4 Aluminum 0.02-0.06 Iron Rest —-- η —— Hardness HRC in the cast state in the workpiece cross-section, mm Impact viscous bone, J / cm ² Coefficient of relative wear resistance Alloy The content of elements, wt.% FROM St V Mp Si A1 other items 15x15 | 15x15 1 1.90 **, sz 6, AO 2,55 0, A9 0.06 59-61 59-61 12-15 3,7-M 2 1.78 5.50 5.76 3.20 0.32 0,03 58-60 59-61 25-32 3,5-3,8 3 1,56 4.12 5.03 2.86 0.90 0.02 58-60 58-60 18-22 3.4-3.7 b . '.'•in 3.80 4.71 1.85 0.64 0,03 60-62 58-60 20-2 * 1 3.5-4.0 5 1.38 * 1.35 3.80 2.97 0.58 0,0A 58-60 58-60 28-35 3.4-3.6 .6 2.12 6.53 6.58 1.95 0.62 0.08 60-62 58-60 8-10 3,8-A, 3 7 1.6 * 1 7.18 7.53 1.80 1.17 0,0A 51 ”-56 52-5 * 1 8-10 2, * 1-2.8 8 1.26 S, ^ ¹ " 2.96 3.1 * 2 0.38 0.01 55-57 57-58 26-32 2.4-3.0 Proto- a type 1, Ab 6.21 5.10 0.58 1.83 0.32 0.64 Io 1 57-59 52-5 <ι 8-10 2.8-3.1 0.15 REE