RU2753362C1 - Method for surfacing copper alloys on steel - Google Patents

Abstract

FIELD: metallurgy.SUBSTANCE: invention can be used in the manufacture of parts consisting of dissimilar materials, namely by surfacing a copper alloy on a steel part. The mold for surfacing is made by welding side and end steel strips to the original steel part. The inner surface of the resulting mold is cleaned by shot blasting. A flux is introduced into the mold and a copper alloy is placed in it, on which the flux is additionally applied. Dissimilar materials are heated in an electric furnace to a temperature higher than the melting point of the deposited material and lower than the melting point of steel. The side steel strips of the form are cut off from the resulting bimetallic part.EFFECT: invention reduces the cost of implementing the method, increases the physical and mechanical properties of the bimetallic compound.1 cl, 3 dwg

Description

The invention relates to the field of mechanical engineering and can be used in the manufacture of parts consisting of dissimilar materials.

A known method of manufacturing bimetallic castings from two dissimilar in chemical composition and with different melting points of alloys [RF patent for invention No. RU 2267378, IPC B22D 19/16, published 01/10/2006].

The method consists in the following: a more refractory alloy is poured onto a workpiece cast from a more low-melting alloy and installed in a casting mold (chill mold) at a temperature of 10-20 ° C higher than its temperature of zero fluidity at a rate of movement of the melt in the form of 0.1-1 m / s.

Disadvantages of this method:

- specialized equipment is required - chill mold;

- defects in bimetallic casting are possible - slag inclusions due to insufficient quality preparation of the metal; shrinkage defects (cavities, porosity) due to a violation of directional solidification; cracks arising due to high pouring temperature caused by chill casting (literature source: “Chill casting” / Gordeeva Yu.Yu. // Siberian Federal University);

- high cost of making bimetallic casting due to the use of casting in a chill mold - long preparation for casting, casting in a chill mold, subsequent control cooling of molten metal (literature source: "Foundry technology" / Titov N.D., Stepanov Yu.A. / / publishing house "Engineering", 1974 - S. 371).

A common feature of an analogue and a prototype is:

- obtaining a bimetallic compound (copper alloy and steel).

The closest to the invention in technical essence and the achieved effect is a method of surfacing copper alloys on steel [USSR patent for invention No. SU 1779502, IPC V23K 09/04, published on 07.12.1992].

The method consists in heating dissimilar materials to a temperature higher than the melting point of the material being deposited (copper alloy) and a lower melting point of steel (about 1100 ° C) in a salt bath, to increase the geometric accuracy of manufacturing in the steel part before surfacing, a cavity (shape) is made, in which is deposited with a copper alloy, after which the final machining is performed.

Disadvantages of this method:

- the high cost of manufacturing bimetallic parts due to the machining of the steel billet prior to surfacing and the use of salt baths for heating the steel base and copper alloy insert up to 1100 ° C;

- the use of specialized equipment is required to immerse the part in a salt bath;

- the operation of increasing the surface roughness of the cavity in the steel part before the surfacing operation is not provided for increasing the adhesion between the steel and the copper alloy after surfacing, which reduces the physical and mechanical properties of the bimetallic joint.

Common features for the prototype and the claimed invention are: making a mold for surfacing a copper alloy, introducing a flux into a mold, installing a copper alloy in a mold, heating dissimilar materials to a temperature higher than the melting point of the weld material and a lower melting point of steel, final machining.

The tasks to be solved by the claimed invention are: reduction of labor and material costs for the implementation of the method while ensuring the geometric accuracy of the bimetallic joint, increasing the physical and mechanical properties (adhesion) of the bimetallic joint.

When solving the assigned tasks, the following technical results are achieved:

- increasing the physical and mechanical properties of the bimetallic compound (tensile strength, shear strength);

- reduction of labor intensity and material costs - mechanical processing of the steel part before surfacing is excluded to obtain a shape in the form of a cavity for surfacing; excludes the use of expensive equipment, such as salt baths (replacement with an electric furnace), as well as specialized equipment necessary for immersing a part in a salt bath.

The claimed technical solution meets the criteria of novelty and inventive step as has distinctive features from the prototype, is characterized by a new set and sequence of essential features, which makes it possible, when using the invention, to solve the set tasks and obtain new technical results in comparison with the identified analogues and the prototype.

The method is illustrated by figures. In fig. 1 shows the manufactured form for surfacing, Fig. 2 - deposited bimetallic part, in Fig. 3 - bimetallic part after machining.

The method is carried out as follows.

A mold is made (Fig. 1) for surfacing a copper alloy by welding side 1 and end 2 steel strips (St3sp material) to the original steel strip 3 (St3sp material). After that (before surfacing), shot blasting of the inner surface of the mold is performed (cleaning from oxides and increasing the roughness on the initial steel strip). A mold is installed for surfacing on the pallet of an electric furnace of the SNOT or SSHO type. Then PV200 flux is poured into the mold. After that, the material to be welded is installed in the mold - a bar or sheet 4 (LS-59-1 material). To enhance the effect of the covering role of the flux, PV200 flux is poured onto the surface of the bar or sheet 4. Next, the furnace tray with the prepared mold is moved into an electric furnace and switched on for heating to a temperature (950-980 ° C), a higher melting point of the material being welded (LS-59-1) and a lower melting temperature of steel. The surfacing time is set depending on the number of prepared forms (from 1 to 10 pieces) and can reach from 30 to 90 minutes. After surfacing the copper alloy on steel (Fig. 2), the final machining of the bimetallic part is performed (Fig. 3) - side strips of 1 form are cut off.

As a result of surfacing, in contrast to the prototype, a bimetallic joint was obtained, which has the following mechanical properties: the tensile strength of the fusion zone of the brass and steel sections is at least 15 kg / mm ² , the shear resistance is at least 12 kg / mm ² . The indicators correspond to the specified parameters laid down in the design documentation. When testing for bending in accordance with GOST 6996-66, there are no delamination areas along the fusion line of the copper alloy and steel. According to the results of metallographic control, the absence of lack of fusion, pores and cracks between the steel and the copper alloy was recorded. These indicators in the manufacture of bimetallic parts according to the prototype method were not achieved (the ultimate strength of the fusion zone of the brass and steel sections was 9 kg / mm ² , the shear resistance was 10 kg / mm ² ).

Making the mold by welding steel strips made it possible to exclude the machining of the steel part before surfacing. The preparation of the inner surface of the mold by shot blasting made it possible to increase the mechanical properties (adhesion) of the bimetallic joint. Heating of the prepared form is carried out in an electric furnace, which significantly reduces labor and material costs in comparison with the use of salt baths. Eliminates the need to use specialized equipment required for immersing the prepared form in the technical heating means (salt baths).

The inventive method of surfacing a copper alloy on steel in comparison with the prototype allows to reduce labor and material costs, to improve the physical and mechanical properties of the bimetallic joint.

Claims (1)

A method of surfacing a copper alloy on a steel part, including making a mold for surfacing a copper alloy, introducing a flux into the mold, placing it in the form of a copper alloy and heating dissimilar materials to a temperature higher than the melting point of the material being deposited and a lower melting temperature of steel, characterized in that the mold is surfacing is made by welding to the original steel part of the side and end steel strips, after which the inner surface of the resulting shape is cleaned by shot blasting, after placement in the form of a copper alloy, additional flux is applied to it, and dissimilar materials are heated in an electric furnace, after which side steel strips are cut off from the bimetallic part.

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