SU1655686A1 - Method of composite arc deposition - Google Patents

Abstract

The invention relates to arc melting and can be used in the recovery of worn machine parts and in the application of wear-resistant coatings on new parts. The purpose of the invention is to improve the quality of the coating by reducing the dissolution of powder particles in the matrix metal. In arc welding of composite coatings on low-carbon steel parts, a gas jet perpendicular to the weld surface is first supplied to the tail part of the bath. At an angle of 40-50 & After the pause, which is sufficient to fill the tail part of the bath with liquid metal, the jet stream is also fed to the tail part of the bath. The gas jet blows liquid metal from the tail end of the bath, leaving a thin layer of liquid metal gas spray jet on the rear wall of the bath, at an angle of 40-50 ° C. The surface is perpendicular to the crystallization surface on the back wall of the bath and introduces powder particles into the layer of liquid metal. The time of action of each of the jets and pauses are approximately the same. 3 silt, 1 tabl y

Description

The invention relates to methods for arc surfacing in a protective gas environment and can be used in the restoration of worn-out machine parts, as well as in the application of wear-resistant coatings on new parts from low carbon steels.

The purpose of the invention is to improve the quality of the coating when surfacing on parts from low carbon steels by reducing the dissolution of powder particles in the matrix metal.

FIG. 1 shows a gas jet action pattern; in fig. 2 is a diagram of the action of the gas-powder jet; FIG. 3 shows the position of the molten metal of the bath at the moment of pause.

The method consists in the fact that during arc surfacing of composite coatings on low-carbon steel parts, a gas jet perpendicular to the weld surface is first supplied to the tail section of the bath, then a gas spray powder is fed to the tail section at an angle of 40-50 °, and after a pause sufficient to fill the tail end of the bath with liquid metal, the jetting is repeated.

Under the action of a gas jet, the weld pool metal moves in such a way that only a thin layer of molten metal remains in the tail section, which is located along the crystallization front (Fig. 1). Next, the flow of the gas jet is stopped, and include the supply of gas powder jets. At the same time, particles of the powder additive are embedded in a thin layer of molten metal and. been micro-refrigerated, leading to accelerated

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crystallization layer (figure 2). In this way, a thin metal layer is obtained with interspersing solid particles. The next time after the gas powder jet stops supplying during the pause period, the molten metal from the head part of the weld pool under the action of hydrodynamic forces generated by an electric arc, moves to the tail part, closing the formed part of the coating (Fig. 3), is fused with it, thus preparing the next cycle, which begins with the supply of a gas jet and the displacement of metal from the tail end of the weld pool. In this case, the surface of the already applied layer is covered by a thin layer of liquid metal covering the layer applied in the previous cycle. This layer is essential for forming the next layer of particles. The maximum concentration of powder particles in the layer, their minimum melting, the optimum thickness of the liquid layer over the particles is provided with the duration of the pause, determined by the time of filling the tail part of the surfacing bath with the liquid metal. The coating is a matrix metal layer containing a significant amount of powder additive with minimal melting.

The range of variation of the surfacing speed of composite coatings according to the proposed method is 8.5-10 m / h. With these values of speeds, the highest efficiency of the process and the maximum wear resistance of the coating are achieved.

When surfacing parts of low-carbon steels of the St 3 type, Sv-08tG2S wire is used as a melting electrode, the fraction of the electrode material in the matrix layer is 65-75%. The angle of inclination of the crystallization front on the rear wall of the bath is in the range of 40-50 °. The angle of inclination of the gas-powder jet at 40-50 ° ensures its perpendicularity to the crystallization front on the rear wall of the bath and improves the condition of the distribution of powder particles over the surface of the liquid

rule in the same place as gas. The duration of the gas, gas-powder jets and pauses are approximately equal.

Example. The coating was deposited on plates made of Stz steel with a thickness of 10 mm. Surfacing mode.

Arc current, A, 400 500

Surfacing speed, m / h -10

Diameter of the electrode (wire Sv-08 G2S. Mm2

Powder additive of relit of brand 3, micron 1000-1800

The speed of the gas jet, m / s20

Speed of gas-powder jet, m / s9

Time of each jet, c2

Pause, s1,5-2

To obtain comparative data, the coating was deposited according to the prototype method under similar technological conditions.

The table shows the results of studies of deposited coatings on the relative wear resistance and the degree of melting of the particles.

The use of the proposed method makes it possible to reduce the melting and dissolution of particles during surfacing, thereby ensuring an increase in the relative wear resistance of composite coatings.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION The method of arc surfacing of composite coatings with a powder spray jet supplied to the surfacing zone of the powder additive, characterized in that. in order to improve the quality of the coating during surfacing on parts from low carbon steels by reducing the dissolution of powder particles in the matrix metal, first, a gas jet is fed into the tail part of the bath perpendicular to the weld surface, then a gas-powder jet is fed at 40-50 ° to the weld after a pause sufficient to fill the tail section of the surfacing bath with liquid metal, the process is repeated. metal. The nozzle of the gas-powder stream on the surfacing, And Preferred way 400-420 420-440 440-460 460-480 480-500 The degree of melting and dissolution. % 7 9 9 ten eleven Table continuation Relative wear resistance standard - steel 45, HRC45 9.0 8.8 8.5 7.9 7.9 Fig.)