SU990415A1 - Method of producing metal-dispersion hardened material two-layer blank - Google Patents

Description

(54) METHOD OF MANUFACTURING A TWO-LAYERED PREPARATION OF METAL-DISPERSABLE-STRENGTH MATERIAL

one

The invention relates to metallurgy, in particular to foundry, and can be used to produce two-layer billets of metal and a dispersion-strengthened material.

There is a known method for producing castings, in which, in order to increase the wear resistance of the surface layer of castings, various solid additives are placed on the working surface of the castings on the side of the castings, for example, granulated aluminum and wear-resistant iron pieces 1.

However, this method is not sufficiently effective when operating under conditions of abrasive wear, alternating loads and high temperatures.

The closest to the technical essence of the invention and the achieved result is a method for producing bimetallic billets, which involve melting the metal billet to a depth of 0.04-0.5 billet thickness, introducing hardening additives into the melt of the melted metal and crystallizing the molten metal under a layer of heated slag with temperature control

slag above the melting point of metal 2.

The disadvantages of this method are the unsatisfactory quality of the castings caused by the appearance of shrink holes and porosity during crystallization, and as a result, the strength and wear resistance of the bimetallic billet are reduced. In addition, in a known manner it is impossible to make a two-layer casting, the base of which has a much lower temperature.

10 melting point than the melting point of the introduced alloying components. For example, the base is zinc, the input components are carbides, borides, nitrides.

The aim of the invention is to increase

, 5 strength, density and wear resistance of a two-layer billet.

This goal is achieved by the fact that according to the method, which includes melting a metal billet to a depth equal to 0.04-0.5 of the thickness of the billet, and introducing reinforcing additives into the melt of the melted layer, melting the plasma to a liquid-solid state, and additives, mainly in the form of carbides, borides, nitrides, are injected into the fused layer by spraying their plasma streams while simultaneously mixing the melt of this layer of the preform, and after forming a two-layer preform, it is pressed into ( emutable matrix) until complete crystallization.

The method is carried out as follows.

The billet is installed in a quartz crucible and is arc fused to the required depth by an arc plasma, after which insoluble dispersed particles are introduced into the melted portion of the billet at the temperature of the liquid-solid state by means of a screw stirrer. Then the workpiece is installed in a separable matrix and is pressed.

Example. Solid billet of zinc-based alloy, May. ° / o: aluminum 9.0–12, copper 1.0–1.5, zinc else, with a diameter of 100 mm and a height of 150 mm, are placed in a quartz crucible. The upper part of the preform is fused with a plasma jet generated by an UPU-ZV arc plasma torch to a temperature of 390 ± 5 ° C, which lies in the temperature range of the onset and end of crystallization. At this temperature, the melt is a stable liquid-solid mass with a high viscosity and high adhesion to solid foreign particles, regardless of their nature and conditions of wetting with a liquid metal. The workpiece is fused to a depth of 50 mm, which is controlled by a metal probe. The mode of operation of the plasma torch: current of 300 A, voltage of 60 V, consumption of plasma-forming gas (argon) 2.8-3.0.

After fusion of the preform-test; 1, boron carbide powder (GOST 3647-71) with a dispersity of 150-180 µm is injected into the plasma jet. When passing through the plasma jet, particles of boron carbide, milled 91, 0

15 18 20

101.3 121.5

They reach up to 50-70 microns and are fed uniformly to the surface by a continuously stirred screw mixer, driven by an electric motor, of a liquid-solid mass. The amount of hardened particles in the volume of the melted metal is regulated by the melt processing time and is 15-20 May. % After the particles are introduced, the mixer is removed. Then, the workpiece is removed together with a quartz crucible and placed in a split matrix, the height of which corresponds to the height of the workpiece. The matrix is placed on the press and the melt is pressed into until the complete crystallization of the core by a punch, the diameter of which corresponds to the diameter of the workpiece.

In the resulting two-layer billet, zinc alloy is a dispersion-strengthened material. The thickness of the zinc alloy layer is 100 mm, and the layer of dispersion-strengthened material, taking into account the introduction of dispersed particles of boron carbide and prepressing 40-45 mm. The workpiece has a high density and reliable connection of the layers.

Tests for wear resistance of a two-layer billet were carried out on an MI-1 type machine with a load of 6 kgf / cm and a sliding surface speed of 0.6 m / s. The counterbody is heat treated steel 45.

The method is suitable for almost all alloys that crystallize in the temperature range of liquidus-solidus, for example, alloys based on Fe, Cu, Ai, Zn, etc.

The field of application of such blanks is determined by the conditions of operation of the parts, which require a combination of high strength and wear resistance of the working part with good viscosity and structural ductility.

Since the hardness of borides, nitrides, and carbides is approximately the same in a particular case, the effect of introducing equal disperse nitrides or borides into the melt is similar to the effect obtained by introducing carbides into the melt. The results are presented in table. 1-3.

Table 1

0,004

107 110 0.003 112 0.003

Claims (2)

1. USSR Author's Certificate No. 501831, / cl. B 22 D 19/02, 974. 2. USSR author's certificate number 697253, cl. B 22 D 19/00, 1979.