Method of increasing of a wear resistance of the cemented carbide tool or a hardware product

FIELD: treatment of the wear-resistant hardware products of the wear-resistant hardware products of an instrumental designation.

SUBSTANCE: the invention is pertaining to the field of treatment of the wear-resistant hardware products of an instrumental designation and may be used for increasing an operational life of gears and tools, components of machines and the devices working in conditions of cutting, friction and an abrasive wear-out. The technical result of the invention is an increase almost in two times of the wear resistance of the cemented-carbide tools or hardware products, predominantly made out of a tungsten-free metal-ceramic alloy based on titanium carbide and nickel-chromium compound (TiC-NiCr). The indicated technical result is obtained by conduct of the treatment of the effective areas of the tools or the hardware products with a pulsing high-current beam coupling with a pulse duration - 2-3 microseconds, power of electrons - 10-30 keV, density of power - 4.5-5.5 Joule/cm2 and a number of pulses - from 10 up to 30.

EFFECT: the invention ensures an increase almost in two times of the wear resistance of the cemented-carbide tools or hardware products.

1 dwg, 1 tbl

 

The invention relates to the field of wear-resistant products from tungsten cermet alloys based on titanium carbide with a metal bond, and more specifically relates to methods of improving the durability of these products is instrumental purpose, and can be used to improve resource tools, machine parts and mechanisms, working in conditions of cutting, friction and abrasive wear.

Known methods of hardening steel products by repeated heating their surfaces to the quenching temperature pulses of high current electron beam [patent RU NO. 2009272, WITH 23 10/60, 21 D 1/09, 1992; patent RU No. 2048606, C 23 C 10/60, 21 D 1/09, 1992]. But they are inappropriate for our task.

The known method of surface treatment of products of structural alloys, mainly stainless steels and aluminum alloys, comprising the irradiation of the working surfaces of articles of high current pulsed beam of charged particles microsecond duration with the energy of the electrons is not more than 40 Kev, the energy density of 10-20 j/cm2and the number of pulses is not more than 10.5 [patent RU NO. 2125615, 21 D 1/09, 1998].

The disadvantage of this method is that it is unacceptable for processing tungsten cermet alloys based on titanium carbide with a metal bond because of the high density energy and electron-beam, that leads to the weakening of the surface of the tungsten-free hard alloys.

The closest analogue of the present invention, the set of essential characteristics is a method of hardening carbide tools mainly on the basis of tungsten carbide with cobalt ligament (WC-Co) and tungsten carbide with titanium carbide with cobalt ligament (WC-TiC-Co), including exposure to the working surfaces of the tool pulsed high-current electron beam with a pulse duration of 2-3 μs, with the electron energy of 10-30 Kev, the energy density in the range of 0.8 to 5 j/cm2and the number of pulses in the series of 5-10. After irradiation carry out annealing tool in vacuum at 850-950°C for 1.5-2 hours [patent RU NO. 2118381, 21 D 1/09, B 22 F 3/24, 1997].

The disadvantage of this method is that referenced irradiation regimes applicable to harden carbide type VC and TC, does not allow to increase the wear resistance of tungsten carbide-based carbide titanium and nickelchromium ligaments. This carbide is widely used in industry for the manufacture of wear-resistant cutting tools, working in conditions of abrasive wear [patent RU No. 2093309, 20.10.1997, bull. No. 29].

The present invention is to develop a method of increasing the wear resistance of tordos the face of the instrument or article, mainly of tungsten carbide-based carbide titanium and nickelchromium ligament (TiC-NiCr) by treating the working surface of the product or tool pulsed electron beam. The proposed solution allows to increase the wear resistance of tungsten metal almost in 2 times.

This technical result is achieved in that in the method of increasing the wear resistance of carbide tools or products made primarily of tungsten carbide-based carbide titanium with nickelchromium a bunch of conduct irradiation of the working surface of the instrument or articles of high current pulsed electron beam with a pulse duration of 2-3 μs, electron energy of 10-30 Kev, the energy density of 4.5 to 5.5 j/cm2and the number of pulses from 10 to 30.

The invention consists in that for increasing the wear resistance of tungsten carbide-based carbide titanium with nickelchromium a bunch of necessary energy density (Es) and number of pulses (N) is chosen in this interval, so that the processing time was partial mutual liquid-phase dissolution of carbide and binder phases at phase boundaries, but lacked complete dissolution karbidnyj of particles in the bunch and there were cracks the surface layer.

The choice of the working interval energy density and number of pulses of the electron beam based on the results of experimental investigation of the microstructure of the surface and cross-section, for example, metal plates before and after electronic processing and durability of these plates in the mode of cutting metal (steel 45) depending on the total energy electron irradiation (energy density beam, multiplied by the number of pulses of electron irradiation). Studies have shown that for small values of the total energy electron irradiation, the high-speed heating of a thin surface layer of the cermet and the large differences in coefficient of thermal expansion of the metal ligaments and particles of titanium carbide is the cracking of the carbide particles, decreases the mechanical strength of the sintered plate and decreases its resistance in the mode of metal cutting. When some average values of the total energy electron irradiation, heated in the surface layer of the plate to a higher temperature, the molten metal bond fills the cracks in the carbide particles, creating a metallic coating around each already smaller carbide particles. The resistance of metal-ceramic plate mode re the project for a metal with a noticeable increase.

A further increase of the total energy leads to the dissolution of the sharp corners of the carbide particles neravnovesnoi form, the seal of carbide particles in the surface layer (volumetric content of carbide particles in the surface layer with a thickness of 130 μm increases by about 4-5%). In a metallic bond the surface layer several times increases the content of titanium and carbon (due to partial dissolution of the carbide particles in the molten metal bond). As a result, the resistance of metal-ceramic plate in the mode of cutting metal increases significantly and reaches a maximum value greater than the resistance of metal-ceramic plate in the original (before irradiation by electrons) about 2 times. A subsequent increase in total energy electron irradiation leads to further increase in the temperature of the molten metal bond directly to the surface of the cermet inserts, carbide particles of this surface layer substantially dissolve in the molten metal cords, the content of carbide particles on the surface of the plate is sharply reduced. As a result, the resistance of the plate in the mode of cutting metal is also significantly reduced.

The drawing shows pictures showing the metallographic structure of the surface metal of the ceramic samples in the initial state (a) and after electron beam treatment in different modes: b)-2 j/cm 2N=5; C)-3 j/cm2N=5; g)-6 j/cm2N=5; e)-5 j/cm2N=30; (e)-6 j/cm2, N=33. Arrows in b) shows the cracks in the particles of titanium carbide.

The invention is carried out as follows.

Cutting inserts (samples) of tungsten metal-ceramics based on titanium carbide with nickelchromium ligament size 12X12X4 mm with polished metallographic class clean surface was placed in the working chamber of the electron-beam system. Polished surfaces were irradiated by electron beam with a pulse duration of 2-3 μs, electron energy of 10-30 Kev, the energy density of 1.5-8 j/cm2and the number of pulses from 1 to 33. After irradiation investigated the microstructure of the surface and cross section of the plates and the resistance plates in the mode of cutting metal (steel 45). The resistance of the plates at the stage of normal wear was evaluated by the width of the pad wear on the rear surface of the h3(h3=0.8 mm) when machining steel at cutting speeds of 102 m/min, feed cutter 0.28 mm/Rev, depth of cut 1 mm, front angle -6°rear angle 6°front angles 45°, auxiliary angles 45°.

Table
The results of measuring the wear resistance of cutting plates and the solid alloy TiC-50 wt.% with nickelchromium a bunch of before and after irradiation of a pulsed electron beam.
The number plateEnergy density, Es,

J/cm2
The number of pulses NThe way of cutting, m
1.--333.6
2.1.51162
3.25122
4.35112
5.45167
6.65162
7.85230
8.510385
9.5.520505
10.4.530482
11.530652
12.633335

The table shows that with a low number of pulses (1-5), regardless of the beam energy density is in the range of from 1.5 to 8 j/cm2tool life is lower than in the initial state (333.6 m). The decrease in resistance due to the occurrence of microcracks on the surface of the samples irradiated in these modes (figb, b, g). When the beam energy density on the 4.5 to 5.5 j/cm 2and the number of pulses from 10 to 30 path of cut increases (see table p. No. 8-10) compared to the original. The increase in resistance of the cutting plate is explained by the formation in the surface layer is uniform, with no signs of cracking microstructure. When the beam energy density 5 j/cm2and the number of pulses N=30 path cutting up to 652 m, tool life increased approximately 2-fold compared to baseline (see table p. No. 11). The increase in resistance of the cutting plate is explained by the formation of the optimal microstructure, in which there was a partial mutual liquid-phase dissolution of carbide and binder phases at phase boundaries and partially melted crystals of titanium carbide firmly secured in the binder phase (figd). A further increase in energy density (N=33) leads to almost complete dissolution of carbide particles in a binder phase and the formation of a grid of micro-cracks and individual microcraters (fige). The presence of microcracks and microcraters, which is the stress concentrators, reduce the wear resistance of the cutting tool to approximately the original level (see table p. No. 12).

The method of increasing the wear resistance of carbide tools or products, mainly of tungsten carbide-based carbide titanium with neither anthropoloy ligament, includes irradiation of the working surface of the instrument or articles of high current pulsed electron beam with a pulse duration of 2-3 μs and the electron energy of 10-30 Kev, characterized in that the energy density of the electron beam is 4.5 to 5.5 j/cm2and the number of pulses from 10 to 30.



 

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