SU1447587A1 - Method of burnishing parts - Google Patents

Abstract

The invention relates to combined methods of surface hardening using the effects of electroerosive doping and frictional hardening surface and can be used to enhance the wear resistance of parts. The purpose of the invention is to increase the wear resistance of parts by increasing the depth and quality of hardening. The method of surface hardening of pre-: intrinsic parts from cast iron involves electroerosive surface doping of interstitial synthesized alloys with subsequent local frictional wear to a depth equal to 0.8-1.0 of the thickness of the synthesized layer. Resists wear resistance 5.2-5.6; depth of hardening, mm, 3.0-3.2. 1 tab. (C (L

Description

Oiik

four

H

cl

00

ten

15

11447587

The invention relates to combined methods of surface hardening using the effects of electroerosive doping and frictional hardening of surfaces and can be used to improve iznostoykost.

The chain of the invention is to increase the wear resistance of parts by increasing the depth and quality of reinforcement.

Example. The proposed method of hardening specimens from SPHN-62 iron with a microhardness of 800-1000 kgf / mm, measured by the method of oblique scratching at an angle of 20 to the surface with a diamond pyramid face forward under a load of 20 g using a PMT-2 device,

The scratch width is measured on a Neaphote-2 microscope with magnification. 20 X 1000. Hardness is calculated from the ratio of the magnitude of the vertical load and the area of contact of the sample with the pyramid. First, the samples are subjected to EDM doping with synthesized implantation alloys (niobium carbides and carbonitrides) to a depth of 20-100 microns. The microhardness of the surface after doping is 2400 kgf / mm. Then, the doped surface of the specimens is subjected to friction wear using a disc made of steel P 18 heated to 700 ° C at a sliding speed of 7 m / s and a pressure of 0.5 MPa. The treatment is carried out to the amount of wear of the doped layer by 0.8; 1.0 from its original depth.

The wear resistance of the hardened specimens of SPXN cast iron is evaluated in a laboratory setup at a sliding speed of 3 m / s and a pressure of 0.2 MPa without additional heating. The counterbody is a disk made of steel 45. As a criterion of wear resistance, the principle taken is 45 and the test duration to sample wear to a depth of 3.5 mm.

The composition of the layer previously synthesized by EDM is selected as follows.

The layer must contain elements with the highest diffusion mobility: carbon, nitrogen, boron, the presence of which increases the depth

35

40

50

Thus, layers containing carbides, nitrides, and borides of refractory metals are fully satisfied with the listed conditions.

In the process of friction processing of the synthesized solid layer, as a result of exposure to high temperatures and intense plastic deformation, conditions are created for the superdiffusion of the alloying elements. This leads to the dissolution of carbides, nitrides, borides of the synthesized layer and the saturation of the base material with alloying elements.

In the first stages of the friction process, a solid synthesized layer prevents excessive damage to the bridge of the still non-strengthened base material; as the thickness decreases, otherwise the layer (as a result of dissolution and wear.) the temperature and deformation effect on the base material increases. At the same time, the degree of hardening of the base material gradually increases, reaching a maximum with a decrease in the thickness of the synthesized layer by 0.8-1.0 from its initial value. It is impractical to lead the process of friction processing further after the complete dissolution of the synthesized layer, since the microhardness of the hardened surface begins to decrease. This is due to the lack of a source of alloying elements that served as the synthesized layer.

The reduction of the synthesized layer during the friction treatment from the initial value to zero is also very important (the function of regulating the temperature and force effect on the base. This allows to obtain stable results with variations in the chemical composition of the base, the synthesized layer and the friction treatment conditions.

The initial thickness of the pre-synthesized layer in general case varies from zero to the maximum values of 0.2-0.3 mm typical for EDM doping. At the same time, after the friction treatment of the cast iron, a reinforced layer appears

hardening during friction processing. depth from 0.1 to 3 mm with a minimum. In addition, the synthesized layers must contain metals that contribute to the bleaching of cast iron - chromium, tungsten, vanadium, titanium, niobium.

NOI microhardness, respectively, from 1500 to 3000 kg / mm.

For each specific part, the required thickness of the synthesized layer

0

five

0 5 0

five

five

0

0

Thus, layers containing carbides, nitrides, and borides of refractory metals are fully satisfied with these conditions.

In the process of friction processing of the synthesized solid layer, as a result of exposure to high temperatures and intense plastic deformation, conditions are created for the superdiffusion of the alloying elements. This leads to the dissolution of carbides, nitrides, borides of the synthesized layer and the saturation of the base material with alloying elements.

At the first stages of the friction process, a solid, synthesized layer prevents excessive damage to the still non-reinforced base material; as the thickness decreases, otherwise the layer (as a result of dissolution and wear.) the temperature and deformation effect on the base material increases. At the same time, the degree of hardening of the base material gradually increases, reaching a maximum with a decrease in the thickness of the synthesized layer by 0.8-1.0 from its initial value. It is impractical to lead the process of friction processing further after the complete dissolution of the synthesized layer, since the microhardness of the hardened surface begins to decrease. This is due to the lack of a source of alloying elements that served as the synthesized layer.

The reduction of the synthesized layer in the process of friction processing from the initial value to zero is also very important (the function of regulating the temperature and force effect on the base. This allows to obtain stable results with variations in the chemical composition of the base, the synthesized layer and the conditions of the friction treatment.

The initial thickness of the pre-synthesized layer in general varies from zero to the maximum values of 0.2-0.3 mm typical for EDM doping. At the same time, after the friction treatment of the cast iron, a reinforced layer appears.

depth from 0.1 to 3 mm with a minimum of microhardness, respectively, from 1500 to 3000 kg / mm.

For each specific part, the required thickness of the synthesized layer

is selected on the basis of these data, taking into account the need for the depth of hardening, the microhardness of the surface and the required performance of the hardening operation, the synthesized layer is monitored on the samples by metallographic and adjusted by the electric spark modes. generator. The duration of the subsequent friction treatment is determined roughly by the color change of the surface to be treated (after wear of the synthesized layer, the surface color changes) and, if necessary, is refined by metallographic analysis of the samples.

The proposed method allows to increase the wear resistance of parts by 2-2.5 times.

Claims (1)

Invention Formula The method of surface hardening of parts, predominantly of cast iron, including electroerosive doping and subsequent surface deformation, characterized in that, in order to increase the wear resistance of parts by increasing, depth and increasing the quality of hardening, the surface deformation is carried out by local frictional wear to a depth equal to 0, 8 - 1.0 thickness of the doped layer. The wear resistance of specimens from SPHN cast iron after hardening is given in the table. Famous Lenirovanie + running in roller0,3 Doping0,1 Proposed Alloying + friction-on running-in to wear: 0.81 from a depth of 3.0 1 alloyed 1, 1 st layer 3.2 The wear resistance of the alloyed specimen without hardening taken for 1.