RU2100456C1 - Method of hardening objects of carbon, alloyed, high-alloy, and quick- cutting steels, and hard alloys - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: object is heated and quenched being simultaneously exposed to acoustic field. According to invention, on heating, temperature equal to 0.15-0.95 that of the initiation of austenite formation is attained and quenching is led to negative temperature equal to 0.5-2.0 that of the initiation of martensite formation, while acoustic field frequency is maintained within the range 150 to 1500 Hz, sound pressure being 160-180 db. Heating and treatment times are determined by object dimensions. EFFECT: enhanced hardening process.

Description

 The method of hardening products from carbon, alloy, high alloy, high speed steels and hard alloys.

 The present invention relates to metallurgy, and more particularly to the hardening of products and tools made of tool materials and hard alloys.

A known method of hardening tools made of carbon, alloy and high speed steels due to heat treatment, including hardening and tempering. For example, heat treatment of P18 steel is carried out according to the following regime: quenching temperature 1280 ^o C, cooling medium oil, tempering at a temperature of 560 ^o C, 3 times for 1 hour. As a result, the steel structure consists of martensite, carbides and residual austenite (≈5 %) (Gulyaev A.P. Metallurgy. M. Metallurgy, 1986, p. 355-379).

 A disadvantage of the known method of hardening these steels by heat treatment is that the products (tool) have insufficient wear resistance due to the increased level of residual austenite and the presence of internal stresses in the product.

 There is also a method of hardening tool steels (The influence of ultrasound on the properties of hardened high-speed steel P6M5, Suschiy V.A. Pogodina-Alekseeva M, Biront V.S. Metallurgy and heat treatment, 1982, No. 11, p. 32), adopted as a prototype , in which the tool was exposed to ultrasound (RCD) after completion of quenching and tempering. Ultrasonic processing was carried out on a setup consisting of a magnetostrictive transducer, an ultrasonic oscillation generator (f≥20.000 Hz) and a stand for mounting and preloading samples with a return spring waveguide to a stepwise transducer hub.

The temperature of the processed tool at the "UZO" was maintained in the range of 20-25 ^o C. The resistance of the thus-drilled drills with a diameter of 7 mm made of P6M5 steel increased ≈1.5 times in comparison with drills subjected only to heat treatment. However, in many cases, an increase in resistance of ≈1.5 times is not enough.

 The main disadvantage of the known prototype method is the insufficient durability of the tool, hardened by known technology.

The present invention has the task of increasing the wear resistance of the tool and products made of carbon, alloyed high-speed steels and hard alloys. In the proposed method, hardening is achieved by heating the product to a temperature of (0.15-0.95) Ac, and during the cooling process, the product is exposed to an acoustic field created by a jet sound generator (GGZ) with a sound pressure of 160-180 dB, the frequency of the acoustic field range 450-1500 Hz, while the product is subjected to cold treatment to a negative temperature equal to (0.5-2.0) Mk, where Ac is the critical temperature for these steels in ^o C; MK the temperature of the end of the martensitic transformation in ^o C.

Example. As an example of the proposed method of hardening, a cutting tool made of high-speed steel P6M5 was used. A batch of 10 drills (6.1 mm in diameter) that previously underwent a heat treatment cycle according to the following conditions: quenching temperature 1220 ^o C, cooling medium oil, tempering at a temperature of 560 ^o C 3 times for 1 hour; heated to a low tempering temperature, held for 10 minutes, then the drills are placed in the resonator of a gas-dynamic sound generator, where they are cooled under the influence of an unsteady gas flow in the sound field with a sound frequency range (450-1500) Hz and sound pressure level L = ( 160-180) dB for (5-10) min, after which the temperature of the product is lowered to a value of (-70 +100) ^o C and the product can withstand additional time depending on its size and weight. The test results of the drills are given in table. 1, where CTAO cryogenic thermoacoustic treatment; THEN heat treatment (according to the mode given in the analogue for drills from P6M5.

 As can be seen from the results given in table. 1, going beyond the specified parameters of acoustic processing and recommended temperature ranges does not take into account the tool life, or reduces it.

 Comparative wear resistance of a tool subjected to heat treatment (TO) and cryogenic treatment with an acoustic field (CTAO) is given in Table. 2.

 As can be seen from the table. 2, the inventive processing method provides an increase in tool life by 1.2-3.5 times, which is associated with a decrease in the amount of residual austenite and residual stresses during thermoacoustic processing.

Claims (1)

The method of hardening products from carbon, alloy, high alloy, high-speed steels and hard alloys, including heating the product with subsequent cooling, characterized in that the product is heated to a temperature of (0.15 0.95) Ac ₁ , and in the process of cooling the product is exposed the acoustic field created by the gas-jet sound generator with a sound pressure of 160 180 dB, the frequency of the acoustic field 450 1500 Hz, when this product is subjected to cold treatment to a negative temperature equal to (0.5 2.0) M _k , where Ac ₁ is critical temperature for the indicated steels, ^o С; M _{to the} temperature of the end of the martensitic transformation, ^o C.

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