SU1757830A1 - Composition of hard facing mixture - Google Patents

Abstract

Use: induction wear-resistant cladding. The essence of the invention: the mixture contains components, wt.%: Iron scale 4-10; boron carbide 4-9; hard alloy else. The introduction of iron oxide in the composition provides a highly dispersed hypereutectic structure.

Description

The invention relates to welding production, in particular, to the composition of the charge for induction welding, and can be used for surfacing fast-wearing surfaces of working bodies of agricultural machines.

Known charge for surfacing containing the following components, wt.%: Iron oxide 13-16

Ferrochromium 72-78

Ferroboron Else

A disadvantage of the known mixture is a high melting point, as a result of which a significant penetration of the base metal and dilution of the bimetal with the base metal are observed in the bimetallic compound. Due to the high rate of crystallization, the weld pool does not always have time to completely degass, which leads to defects in the weld layer.

Closest to the proposed composition to the technical essence and the achieved effect is the charge for surfacing, containing components, wt.%: Hard alloy 77-87,5

Boric anhydride5,2-11,1

Bura5-5,4

Silikokaltsiy1.5-1,8

Carbide boron 0.5-6

However, during the deposition of a known mixture, carbon and alloying elements are burned out and excessive deposition of the deposited metal with the base metal occurs, which leads to the development of structural zones in the deposited metal. possessing the lowered mechanical properties. As a result, the wear resistance and the service life of the weld parts are reduced. The aim of the invention is to increase the wear resistance of the deposited bimetal blade and hardness.

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 This is achieved by the fact that iron oxide is additionally introduced into a mixture for hardfacing, containing a hard alloy, boron carbide, in the following ratio, wt.%:

Iron oxide 4-10

Carbide boron4-9

Hard alloyEverything

It is known that iron scale, together with boron carbide and sodium fluoride (B / jC + FeO + NaF), is used for diffusion saturation (up to 200 µm) of the surfaces of machine parts.

However, research in the field of induction cladding allowed the use of iron scale in combination with boron carbide and hard alloy to obtain a thermosetting mixture, which makes it possible to obtain wear-resistant layers of 0.3-2.0 mm.

The main components used are hard alloy PG-PS-14-60, boron carbide, iron oxides Rv20z. FeO and technical dross.

When heated to a certain temperature in the composition, boron carbide + iron scale there is a strong exothermic interaction consisting of two stages. In the first stage, the reduction of iron from oxide occurs and the oxidation of boron and carbon; in the second, the interaction of reduced iron and the base metal with the formation of borides and carbides, and oxides of boron and carbon in the highest valence form of BaO3 and CO2. Therefore, additional introduction of fluxes into the mixture is not required.

The formation of the layer structure occurs from a liquid state; in the upper part of the layer, the structure is hypereutectic (70-75%); in the lower eutectic (10%) with hypoeutectic components {10-15%) near the base metal.

The hypereutectic zone consists of excess inclusions of borides FeB, FeaB, boron-cementite Fe2 (C, B) with microhardness. Accordingly, No.ev 16700-21580 MPa, No.98 12900-16700 MPa, But, 98 8600 -12900 MPa.

PRI me R. In laboratory conditions, the Institute was prepared by mixing powder materials with a granulation of 0.16 mm, containing, in wt.%:

Iron oxide6.0

Carbide boron6,0

Hard alloy88

High alloy alloy PG-PS-14-60 according to TU 48-19-122-74, boron carbide according to TU-48-4260- 10-84, iron scale Rv20z are taken as the hard alloy.

The mixture of powders was mixed in a laboratory blender for 15 minutes to form a uniform charge for surfacing.

Similarly, another 4 were cooked.

composition of the proposed mixture with different content of components and the composition of the prototype. In tab. 1 shows the composition of the tested surfacing charge and the charge of the prototype.

0 Each of the prepared gpstav of the charge was deposited on flat samples of steel grade st. 3 dimensions 60x25x4 mm in the same loop loop inductor of the high-frequency installation VCHI-bZ / 0.44. The height of the deposited layer was 1.1-1.2 mm.

5 Each of the prepared compositions was deposited on 10 samples.

The weld samples were subjected to comparative tests according to the following parameters;

HRC hardness was determined in accordance with GOST 9613-56;

the relative wear resistance of directional alloys was determined on an X4-B machine in accordance with GOST 17367-71; tendency of weld metal to

5 brittle fracture was determined by the number of blows to complete destruction in accordance with the methodology developed by Rostov-on-Don NIITM.

The essence of the technique is

As with a vertically mounted, weld and sharpened at an angle of 20 °, a sample is struck by a series of strikes of a free-falling striker, the force of which strikes remains constant throughout the entire test cycle.

5 The destruction of the blades with a blunting of 0.2 was carried out on contact with the counterbody with a hardness of HRC 18. The tendency of the hard alloy to brittle fracture was determined by the number of impacts until complete destruction.

0 In the table. 2 presents the results of the comparison of the properties of the proposed and known charge,

From tab. 2 shows that the introduction of iron oxide together with boron carbide and

5, a high-alloyed alloy allows to increase the wear resistance and hardness of the deposited alloy.

The content of iron oxide less than 4 May,% does not provide a significant improvement in strength properties, and an increase in the content of iron oxide more than 10 May. % leads to an increase in the brittleness of the deposited alloy, although the wear resistance and hardness are quite high.

5 Thus, the use of the proposed mixture improves the hardness and wear resistance of the deposited alloy, as a result of which

service life of parts made of quality steel by 2-3 times.

Claims (1)

Claims The composition of the charge for surfacing, containing hard alloy, boron carbide, characterized by that. which, in order to increase wear resistance and hardness, it additionally contains iron oxide in the following ratio, wt.% Iron scale Boron carbide Hard alloy 4-10 4-9 Else Table 1 table 2