RU2303651C1 - Method for strengthening of a long-measuring steel body of rotation - Google Patents

Abstract

FIELD: the invention refers to chemical thermal treatment and may be used for strengthening of the details of a machine.

SUBSTANCE: metal of the fourth-sixth groups in the ratio calculated on the equitation of the reaction of the synthesis of alloys of introduction is put on the surface. The speedy heating is executed with currents of high frequency at which the process of self-propagating high temperature synthesis is initiated. Simultaneously with passing of the self-propagated high temperature synthesis deforming is carried out by way of rolling of the strengthening surface with degree of deformation 7-12% with immediate cooling of water-air mixture.

EFFECT: increases durability of details working in conditions of friction.

1 dwg

Description

The invention can be used in hardening the metal surfaces of machine parts by chemical-thermal treatment (applying a hard wear-resistant coating to the metal surface).

A known method of producing a wear-resistant product (RU 2093309 C1, 20.10.1997, B22F 7/04), comprising applying a layer of powdered refractory material to the surface of the supporting metal base, connecting it to the base by compaction, heat treatment and simultaneous melt impregnation of the metal, the melting temperature of which below the melting temperature of the base metal.

The method allows to obtain a sufficiently hard surface layer, contributing to ensuring the wear resistance of the part.

The disadvantages of this method are:

- significant duration and complexity of the process;

- the inability to obtain a surface with low roughness.

A known method of surface hardening of machine parts (RU 2098509 C1, 10/12/1997, C23C 8/60), including preparation by pressing of plates (applications) from a saturating powder mixture, which are superimposed on the place to be saturated, after which the high-frequency TV is cycled, tightly pressing plates to the surface, and the part is displaced relative to the plates while softening their inner layers.

The method allows for the diffusion saturation of the surface layers of hardened machine parts with various chemical elements from solid phases.

The disadvantages of this method are:

- uneven application of the alloying layer and the need to have a large amount of allowance for machining;

- insufficient adhesion of the coating material to the base material.

A known method of coating metal surfaces of bodies of revolution (RU 2000114597 A, 06/10/2002, C23C 24/02 - taken as a prototype), including coating in the form of a powder on a surface moistened with electrolyte, and simultaneously pressing the powder with rotating rollers on opposite sides of the part with a force exceeding the yield strength of the applied material, while the rollers are connected to the positive pole of the power source, and the workpiece to the negative pole of the power source.

This method allows to increase the wear resistance of parts operating in friction conditions and to eliminate some of the disadvantages noted in previous methods.

However, this processing method also differs in the duration of the process, does not provide sufficient diffusion of the coating material in the base metal.

The objective of the claimed invention is a significant increase in hardness and wear resistance of the treated surface with a combined mode of performing operations of alloying it with a hard alloy of thermomechanical hardening treatment and smoothing action with a tool with the formation of a directed microrelief on the surface of the part.

The problem is solved by pre-normalizing the part, conducting self-propagating high-temperature synthesis in the process of thermomechanical treatment with smoothing of the surface layer and immediate cooling with a water-air mixture.

The essence of the invention is as follows. On the surface of a pre-normalized part made of less scarce (cheaper) material, a suspension of an exothermic (high-energy) mixture with introduced and uniformly distributed metals of 4-6 groups is applied in a ratio calculated by the equation of reaction for the synthesis of interstitial alloys. High-speed high-temperature heating is produced at which the process of self-propagating high-temperature synthesis is initiated in order to obtain a polydisperse coating based on interstitial alloys. Simultaneously with the passage of the SHS process, a deforming load is applied by rolling in a hardened surface with a degree of deformation of 7-12% with immediate cooling with a water-air mixture. At the same time, they provide high adhesion strength of these implantation alloys to the base by mutual penetration due to deformation of the surface layer and hardening of the part. A significant increase in the density of dislocations occurs in the surface layer.

In contrast to the known methods, the proposed process is characterized by a low cost of equipment, safety. The traditional mechanical diamond abrasive finish is eliminated, as the dimensional accuracy and surface roughness required by the operating conditions are achieved.

The drawing shows an example of a specific use for rolls of a cold rolling mill. The blank 1 was taken with a diameter of 13 mm from 9XC material. A mixture was prepared with the composition calculated in accordance with the synthesis reaction: 2Ti + 2 (CH) _n = 2nTiC + nH ₂

1/2 Mo + S = 1/2 MoS ₂

1/2 Mo + Si = 1/2 MoSi ₂

Preparation of the starting mixture.

In a mortar, 48 g of titanium powder was granulated by granulation up to 40 μm, 24 g of molybdenum powder by granulation up to 20 μm, 12 g of carbon powder (soot), 2.1 g of sulfur powder, 14 g of amorphous silicon and transferred to a container where zapon-varnish was added in the amount of 3-5 drops of varnish consistency of drying oil (cream) per 1 cm ^{3 of} powder (~ 2 g) and acetone in the amount necessary to create the consistency of oil paint (liquid sour cream). The resulting composition was thoroughly mixed and applied with a brush to the workpiece. After coating with an exothermic mixture 2, the workpiece was subjected to thermomechanical processing with a continuous sequential action: heating in the inductor 3 to 1000 ° C. During heating, the mixture spontaneously ignited and a self-propagating high-temperature synthesis reaction took place with deformation in the rollers 4, where it was crimped with a degree of deformation of 10%; after leaving the deformation zone, it was cooled in the shower unit 5 with water. The result was a heat-strengthened billet. The hardness on the surface was 62-64 units. HRC, roughness - not more than 10 microns. Next, grinding and polishing to a roughness of 0.4-0.5 microns was carried out.

The resulting rolls were used for rolling a particularly thin tape 0.01 mm thick. In this case, the roll resistance increased in comparison with the rolls obtained by import (Japan, Sweden) by 1.6-1.8 times.

Thus, as a result of using the proposed method in the surface layer of the workpiece, a structure is created that is thermally hardened by alloyed hard alloy with a regular surface microrelief and a predetermined roughness, which ensures high wear resistance of joints operating under severe friction conditions, aggressive environments, etc.

Claims (1)

A method of hardening the surface of a long steel body of revolution, including its normalization, coating, thermomechanical treatment, characterized in that in order to obtain a polydisperse coating based on interstitial alloys, a suspension of an exothermic mixture containing uniformly distributed metals of 4-6 groups in it is applied to the surface in the ratio calculated according to the reaction equation for the synthesis of interstitial alloys, high-speed currents are produced by high-frequency currents, at which a self-propagating process is initiated I high-temperature synthesis, at the same time with which the deformation is carried out by rolling in a hardened surface with a degree of deformation of 7-12% with immediate cooling with a water-air mixture.