SU381496A1 - METHOD OF MAKING BIMETALLIC PIPES - Google Patents

Description

one

A known method of manufacturing bimetallic pipes, in which billets with prepared contact surfaces are inserted into another with a gap, then subjected to joint by joint deformation, for example by drawing, and subsequent thermal diffusion treatment.

The proposed method consists in that in order to ensure a strong bond between the layers of tin phosphorus bronze I1 steel and impart a high wear resistance to the layer of tin phosphorus bronze, thermal diffusion treatment is carried out at 900-920 ° C, after which the pair is deformed, for example rolling with compression 25-60%.

The bronze tube is rolled or cold drawn to the desired size, after which its outer surface is prepared (activated) for welding (by mechanical, chemical, electrochemical, or other processing). The contact surface of steel pipes is prepared (activated) by mechanical or chemical treatment, after which a bronze pipe is introduced into it with a gap. The steel pipe can be cold-rolled (cold-worked) or heat-treated, depending on the ratio of the thickness of the layers and the method of deformation used to bring the contact surfaces in contact.

The contact of articulated pipes is achieved, for example, by debugging or mandrel drawing and subsequent distribution. The method of deformation is chosen depending on the size of the layers of steel and bronze.

The bilayer tubes thus obtained are subjected to thermal diffusion treatment in a chamber or continuous furnace with or without atmosphere protection at 900-

920 ° C. Moreover, when using OF7-0.2 bronze, the heating temperature is 900 ° С, when using BrOFb-0.15-910 ° C, and when using BrOF4.5-0.2-920 ° C. The delay time at the indicated temperatures

is 45-60 min.

Due to the fact that bronze has a greater linear expansion coefficient and at the boundary of the layers there is a preliminary tension due to the elastic aftereffect of the metals being joined, they create contact pressures that ensure the layers adhere.

During thermal diffusion heat treatment of pipes in the bronze layer, a coarse-grained phosphide eutectic is formed, which has high hardness and makes it very hard and unsuitable for use as bearings. For crushing phosphide eutectics and imparting a layer of tin-phosphorous bronze

increased wear resistance obtained

After thermal diffusion treatment, bimetallic tare is cold rolled on HPT mills with a reduction of 25-60%.

If the degree of deformation is greater than 60% without intermediate treatment, tears arise at the eutectic grain boundary and the bond of layers may be destroyed.

After cold deformation, the pipe is heat-treated at a temperature below the temperature of the recrystallization of the main layer and below the temperature of formation of a phosphide eutectic in chamber or continuous furnaces with or without protective atmosphere. For example, for pipes Art. 10 - + - bronze OF7-02 treatment takes place in a chamber furnace at 600 ° С, and e is passed at 650-700 ° С.

In the manufacture of small pipes, the cycles are repeated.

The subject of invention

A method of manufacturing bimetallic pipes, including joint deformation of pipes inserted one into another with prepared contact surfaces for tight contact of layers, for example, by drawing, and subsequent thermal diffusion processing, characterized in that in order to ensure a strong connection between the layers of steel and tins phosphor bronze and increase the wear resistance of the tin layer of phosphorus bronze, thermal diffusion treatment of the articulated pair is carried out at

900-920 ° C, after which it is subjected to cold deformation, for example irokatke with compression of 25-60%.