Page 12 - ST Sept

METALWORKING EQUIPMENT METALWORKING EQUIPMENT
AND TOOLS AND TOOLS
TECHNOLOGY OF CREATION OF WEAR- processing is carried out in certain modes. Before a three-layer gradient structure is formed on

processing, they are applied to the surface the surface, consisting of a hardened layer
RESISTANT SURFACE with a coating, pre-mixed with a consistent 180 ... 220 μm thick (Fig. 1, layer 1), the
graphite lubricant in a certain proportion (for first lower sublayer 200 ... 250 μm thick (Fig.
LAYERS IMPLANTED better electrical conductivity). Tungsten carbide 1, layer 2), the second lower sublayer 20 …

particles are embedded in the formed surface 40 microns (Fig. 1, layer 3) and a matrix
WITH MATERIALS widely and effectively used in the preparation layer, reinforcing it. Then, on the same surface, consisting of normalized 45 steel.
Tungsten carbides W2C and WC are
Microstructural studies were carried out
electromechanical processing is carried out in
BASED ON TUNGSTEN of various functional materials. These hardening modes [2, 3, 4]. on a Zeiss Ultraplus ultra-high resolution field
carbides have high hardness, wear resistance
In the process of high-temperature emission scanning electron microscope based

CARBIDE and refractoriness, which is an exceptional plastic deformation, under the influence of high on Ultra 55, Germany (Zeiss UltraplusField
combination of properties for creating wear-
temperatures and pressures, the surface layer of Emission Scanning Electron Microscope).
resistant and heat-resistant alloys. steel in the contact zone is austenitized. Carbon Fig. 2 shows the microstructure of
As the main alloying element, tungsten from a mixture consisting of graphite and tungsten layers 1 and 2, Table 3 shows the result of
is used in the production of high-speed carbide steels such as R6M5, R6M5K5, R6M5F3 (contain carbides diffuses into the surface layers in the the energy-dispersive analysis of the layers.
9 ... 24 % W), as well as tool steels of various classes (contain from 0.8 ... 1.2 % W to 2.0 ... solid-phase saturation process, increasing the Layer 1 is a mixture of tungsten carbide WC
9.0 % W). Tool steels of the carbide class are characterized by increased heat resistance due carbon content in austenite. Tungsten carbides particles in a steel base. Consequently, in
to the formation of secondary high-alloy martensite with high hardness and stability, as well as also dissolve in austenite up to the limit of its the process of implantation, plastic mixing of
the precipitation of high-strength dispersed tungsten carbides. saturation with tungsten. tungsten carbide occurs in the bulk of steel
Tungsten forms carbide W6Cr in steel, which, during austenitization, partially passes into When conducting research, the friction in a solid state.
a solid solution, providing the receipt of tungsten-doped martensite after quenching, which surfaces of cylindrical specimens were treated Table 3 and Table 4 also contains
hinders the decomposition of martensite upon heating, providing the necessary red hardness of with tungsten carbide powder (Tables 1, 2), the elements Cr and Cu. Their appearance
steel. The undissolved part of the W6Cr carbide leads to an increase in the wear resistance of obtained at the refractory metal plant WOLFRAM is associated with the peculiarities of the
the tool steel. Company CJSC (Unecha, Bryansk region), technology of implantation and hardening
Based on tungsten carbide (WC, W2C), the most effective tool carbide alloys are created, according to the specification of the German [1, 2, 3]. At the stage of implantation, a
containing 85 ... 95 % WC and 5 ... 14 % Co. Heat-resistant and wear-resistant stellite alloys company ElementSixGmbH. roller made of 95KH18 steel is used, and the
(3 ... 5 % W, 25 ... 35 % Cr, 45 ... 65 % Co) are Tungsten carbide powder is applied to the chromium from the roller partially diffuses
deposited on the surface of significantly wearing surface of cylindrical specimens made of 45 steel into the tungsten carbide (point 2, Fig. 2).
machine parts using hardfacing. after normalization using a technology similar to The hardening stage uses a roller made of
However, until now, tungsten carbides have that described in [1]. As a result of processing, pseudo-alloy of tungsten carbide with copper,
been applied to functional surfaces in various
liquid-phase processes (surfacing; laser, plasma,
ion spraying, etc.) Table 1.
In these studies, the goal is to treat the Tungsten carbide powder grade, particle size, oxygen and carbon content.
surface of machine parts made of typical carbon
steel with tungsten carbides by plastic deformation. Tungsten Average Oxygen Total carbon Total carbon Free carbon,
Taking into account the experience gained carbide particle size content of (typical (minimum mass. %
during the implantation of detonation synthesis powder according to mass. % content), content),
nanodiamonds [1], to create wear-resistant
surface layers on the friction surfaces of machine mark Fischer, μm max mass. % mass. %
parts, a combined electromechanical treatment WC 1,0 0,8…1,3 0,20 6,13…6,18 6,08 0,06
technology (hereinafter referred to as СEMT) has WC 1,5 1,3…1,8 0,20 6,13…6,18 6,08 0,06
been developed, including the formation of layers WC 2 1,8…2,5 0,20 6,13…6,18 6,08 0,05
implanted with tungsten carbides, followed by
electromechanical hardening of the treated surface.
The hardening effect during electromechanical
processing is achieved because high rates of
heating and cooling are realized and a high degree Table 2.
of refinement of the austenite grain is achieved, which determines the fine-crystalline structures Chemical composition of tungsten carbide powder in terms of permissible impurities
of hardening of the surface layer, which has high physical, mechanical and operational properties
[2, 3, 4]. Impurity elements, ppm max
The technology is implemented in a special installation. It is a technological complex Al As Ca Cr Na Ni Mo P S Si Fe K
consisting of a universal machine (used for machining work pieces) with appropriate tools and Max 20 20 20 80 20 80 70 20 20 20 100 20
devices for fixing the work piece and supplying high-strength and low-voltage electric current;
power unit for converting industrial electric current; processing mode control unit; means for Min 10 10 10 40 10 40 40 10 10 10 40 10
switching and supplying lubricating and cooling technological medium; unit for interfacing with
a PC.
The implantation of tungsten carbide powder into the surface layer during electromechanical

12 Stanochniy park Stanochniy park 13