SU1680798A1 - Method of steel article nitrocarburizing - Google Patents

Abstract

The invention relates to metallurgy, in particular to the chemical-heat treatment of steel products, mainly from high-speed and alloyed steels, and can be used in machine-tool building, machine-building and other industries for strengthening cutting tools and molds. The purpose of the invention is to increase surface hardness and wear resistance. The method includes heating up to a saturation temperature of 1100 - 1200 ° C and saturation, with a flow rate of 2-4 ml / min., Of fatty amine vapors, quenching and tempering. Diethylamine, methylamine, dibutylamine are used as fatty amines. The use of this method makes it possible to increase the surface hardness of the cutting tool and molds by 1.2–1.3 times, and wear resistance — by 2.0–3.5 times. 1 hp ff, 1 ill., 2 tab.

Description

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The invention relates to metallurgy, in particular to the chemical and heat treatment of steel products, mainly from high-speed and alloyed steels, and can be used in machine-tool, machine-building and other industries for strengthening the cutting tool and the mold.

The purpose of the invention is to increase the surface hardness and wear resistance of cutting tools and molds made from high-speed steels, and to ensure safe operation.

The method includes heating up to 1100 - 1200 ° C and saturating with carbon and nitrogen when feeding at a rate of 2-4 ml / min of fatty amine vapors for 1-1.5 hours, then quenching and tempering. Diethylamine, methylamine, dibutylamine are used as fatty amines.

The drawing shows an installation for carrying out the proposed method of improving the surface of products, a longitudinal section.

The method is carried out as follows.

The casing 1, mounted on the base 2 of the rack 3, is lifted along the guides, opening access to the substrate holder 4 of the article 5, enclosed in sleeves 6, inserted into the holes of the substrate holder 4. The ends of all the sleeves 6, except one, rest on the separator balls 7 rings 8. Since the rod 9 is in the upper position during loading, only one of the sleeves 6 rests on the end face of the washer 10 on the casing 2. By turning on the vacuo

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the smart pump removes air from the chamber 11 through line 12. At the same time, HEAT 13 is disconnected. At underpressure and chamber 11 equal to 1-10 mm Hg, pressure is applied to the rod cavity of the hydraulic cylinder 14. The rod 9 together with the washer 10 Departs from the end of the sleeve 6 inside the spring-loaded glass 15. Under the action of the force of T tinsel, the sleeve 6 with the product 5 also lowers into the spring-loaded glass 15, which together with the rod 9 moves into the depth of the frame 16. When the product 5 located in the quenching unit of the inductor (17 and 18), designed to heat the product to the quenching temperature, amine vapors are fed to the surface of the product through a special inlet at a rate of 2-4 ml / min. When this occurs, the thermal decomposition of amines on the surface of the product and the hardening of the surface due to saturation with nitrogen (formation of nitrides) and carbon (formation of carbides and pyrocarbons) occurs. The dwell time of the product at a given temperature is determined by the depth of hardening of the surface of the product. The hardened product 5 returns to the chamber 11. Increase the pressure in the Borehole cavity of the hydraulic cylinder 14. The rod 9, moving in the opposite direction, brings the product 5 into the chamber 11. At the same time, the edge of the spring-loaded cup 15 enters the opening of the separator ring 8 and stops. The rod 9 with the washer 10, continuing to move, returns the sleeve 6 with the product 5 to its original position. In the chamber 11, the hardened product is heated to 500 - 600 ° C and high-temperature tempering is performed. At the end of the process, the substrate holder 4 is turned by means of the actuator 19. The article 5 is removed from the tempering zone, and another hardening (saturation with nitrogen and carbon) and hardening are applied to its place. After all products 5 have passed through all the hardening and tempering stages, they are removed from chamber 11. The process can be carried out both in vacuum at a pressure of 1–1 mm Hg and in an inert atmosphere at normal pressure. EXAMPLE 1. Non-hardened cutters made from steel R6M5 are heated at normal pressure in argon at 1100-1200 ° C for 1 hour. At the same time, diethylamine is fed to the heating zone of the product at a rate of 2 ml / min, then the treated product let in oil and cool, after which the mill

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subjected to high temperature tempering at 550 ° C. It has been established that the surface micro-flux density is 1700 kg / mm, and at a depth of 50 µm H 1400 kg / cm2. When examining the cutter's surface under an MMP-2R microscope, no cracks were found on the surface,

In table.1 presents the results of studies of the cutters after processing by the known and proposed methods.

PRI mme R 2. A mold made of steel 40X is heated in a vacuum of 1 to 10 mm Hg. at 1100 ° C for 1.5 hours. Dibutylamine-C vapors are fed into the heating zone of the product at a rate of 4 ml / min. When this occurs, their thermal decomposition on the surface of the product and the hardening of the latter due to saturation with nitrogen and carbon. In addition, a glossy graphite film with a thickness of 10 µm is formed on the surface of the product. It was established experimentally that the microhardness of the surface of the product is 1600 kg / mm2, and at a depth of 50 µm kg / mm. The surface roughness before quenching is 34 μm, and after hardening 17 μm.

Table 2 presents data on the durability of the mold for pressing rubber seals.

Thus, the use of the proposed method allows, in comparison with the known method, to increase the hardness of the surface layer by 1.2 - 1.3 times, and the wear resistance of the cutting tool and the mold - by 2 - 3.5 times.

Claims (2)

1. The method of carbonitriding steel products mainly from high-speed and alloyed steels, including I heating to saturation temperature and saturation in decomposition products, liquid hydrocarbons, quenching and tempering, characterized in that, in order to increase surface hardness and wear resistance, heating is carried out up to saturation temperature of 1100 - 1200 ° C, and hydrocarbons use fatty amines that are fed at a rate of 2-4 ml / min. 2. A process according to claim 1, characterized in that diethylamine or methylamine or dibutylamine are used as fatty amines. X 0 processing by a known method (after processing the diameter of the cutter decreased from 2 to 5%). Processing according to a known method (when the amine vapor supply rate is less than 2 ml / min, the wear resistance of the products does not increase, and when the amine vapor supply rate is more than 4 ml / min increases brittleness.). Table 1 Table 2 / 3