SU755363A1 - Method of producing bimetallic rods - Google Patents

Description

The invention relates to metallurgy, specifically to the processing of metals by pressure, and can be used preferably in rolling mills, as well as in drawing and pressing units.

Currently, in order to save costly alloyed steels and alloys, multi-layer (bimetallic) long products having the strength of structural steel 'and a number of special properties of cladding metals are increasingly being used: wear resistance, corrosion resistance, aggressive media, etc. By this knot-15 The days include bimetallic sheets, wires, rods for tracked machine fingers, etc.

A method of producing bimetallic rods is known, according to which a previously prepared carbon steel core and a cladding element in the form of a cylindrical tube of wear-resistant alloy steel 25 are assembled into a bimetallic billet. After welding the ends and heating in the chamber furnace, they are rolled for 6-8 passes in the oval-square * 'C ¹ ! · Caliber system.

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In the known method, the connection of the core and the cladding layer occurs in the rolling process due to molecular adhesion on the contact surfaces 5. The magnitude of the total area of the plots in which the components have adhered, and the depth of penetration of particles of one metal into another determine the quality of the finished bimetallic rods. To ensure the process of welding components into a coherent whole, careful preparation of the surfaces of the joining elements (turning the surfaces of the core and the cylindrical pipe, degreasing, etching in acids, etc.) is necessary. Before heating, an obligatory welding of the ends of each billet is carried out to prevent air entry and oxidation of the surfaces to be joined in the heating process. However, the air remaining in the gaps partially oxidizes the components to be joined, which further reduces the strength of the combination of the components in the finished product.

In the process of rolling due to uneven deformation of the metal over the cross section, which is inherent in almost all

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new package disclosure. This circumstance also adversely affects the quality of the connection of the main and cladding element. Thus, despite careful preparation of the surface of the components to be connected, a large number of technological operations for the preparation of bimetallic packages ^ fail to obtain a reliable connection of the core and the cladding component by molecular adhesion on the contact surfaces.

The aim of the invention is to improve the quality of the connection of the core and the shell and reduce the cost of Assembly of bimetallic billets.

This goal is achieved by taking a billet with a cross-section periodically varying in length as a core, before assembling the bimetallic billet the shell is heated to the temperature of hot deformation and after assembling the billet the shell is deformed together with the cold core.

In FIG. 1 shows a bimetallic billet with a core having a periodic section along the length and perimeter; in fig. 2 - bimetallic billet obtained by hot deformation of a preheated shell together with a cold core; in fig. 3 - finished bimetallic rod, obtained by rolling a bimetallic billet; in fig. 4 - rod obtained by rolling a preheated shell on a cold core.

The technological process of obtaining bimetallic п rods can be carried out in three ways.

In the first embodiment, a hollow shell and a core having a cross-section, periodically varying in length, are made; reinforcing bar can be used as a core. The assembled billet (see Fig. 1) is heated to the temperature of plastic deformation and crimped to the required size and shape, for example, by rolling mill rolls. In the process, rolling metal shells fills the hollows of the core. In the finished bimetallic rolled products (see FIG. 3), the cladding layer of alloyed steel has contact with the core of ordinary carbon steel on a broken surface, which ensures

reliability of coupling elements in the finished bimetallic rod. The dimensions of the shell and core are chosen so that in the finished bimetallic rod the minimum thickness of the cladding layer is 2-4 mm. Such a thickness of the cladding layer meets the requirements that are imposed / for example, on the fingers for tracked vehicles.

As a concrete example in the first embodiment of the proposed method, we consider rolling a bimetallic billet 0 75 mm. The shell is made of steel 40X, the core is made of steel 3. The wall thickness of the shell is 10 mm. The core diameter is 55 mm, and the height and pitch of the protrusions of the core are 2 mm. When rolling a billet heated to 1200 ° C, with a total exhaust p _O Bsch = 14, a bimetallic bar with a diameter of 20 mm was obtained (see Fig. 3). The minimum thickness of the cladding layer is 2 mm, the maximum is 4 mm. At one meter of the bar with this extract, 36 periodically repeated protrusions are obtained, which is sufficient for reliable adhesion of bar elements.

According to the second variant of the technological process as follows. Before assembling the workpiece shell is heated to a temperature of plastic deformation. The assembled billet is crimped, for example, by rolls of a rolling mill, with a hood that guarantees that the sheath is filled with cavities on the surface of the core, while the core remains cold. The result is a blank for rolling, in which the contact between the constituent elements is carried out on a broken surface. Next, the workpiece is heated and subjected to hot deformation similarly to the first variant of the proposed method.

Example. Deform the workpiece ^ 80 mm. The thickness and period of the protrusions of the core are 2 mm. The inner diameter of the shell is 60 mm. Heated to 1200 ° C, the shell is compressed on a cold core, the result is a bimetallic billet 0 75 mm. This billet is heated to 1200 ° C and rolled with a total exhaust of 14. The result is a bimetallic bar 0-20 mm (see. Fig. 3).

According to the third variant of the technological process as follows. A hollow shell is produced, the outer diameter of which exceeds the diameter of the finished bimetallic rod by 2-4 mm. For example, a sheath is made of steel 40X with an outer diameter of 24 mm. It heats up to 1200 ° C and after that a core having a periodic section is inserted into it (maximum diameter 16 mm). The assembled billet is crimped by rolling mill rolls to a diameter of 20 mm (see Fig. 4). In this case, the core remains in a cold state. The resulting bar is a finished product. In the process of cooling, by reducing the temperature,

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it decreases in diameter by approximately 0.2 mm, which increases the adhesion strength of bar elements.

Claims (2)

Claim. 1. A method of producing bimetallic rods, including the steps of assembling the core and the sheath, heating the resulting billet and deformation, differing in that, in order to improve the quality of the connection, they take as a core a billet with periodically changing in. the length of the cross section. 2. The way pop. 1, distinguish So that the shell is heated to a temperature of 5 minutes of deformation before assembly, and after assembly the shell is deformed with the core.