Page 14 - ST Sept

METALWORKING EQUIPMENT METALWORKING EQUIPMENT
AND TOOLS AND TOOLS
and copper, which is in the pseudo-alloy in an unbound state, passes from the roller into a solid Samples with coatings based on Ti-Al-N
solution of austenite. and Mo-Cr-N were manufactured at OOO NPF
Upon cooling, the austenite solution is supersaturated with tungsten, and the excess Plazmacer (St. Petersburg). Comparative tests
tungsten precipitates in the form of a tungsten carbide network (Fig. 2) along the boundaries of of the wear resistance of the samples were
austenite grains lightly alloyed with tungsten. In this case, the resulting structure is identical to carried out on an automated installation based
the structure of cast high speed steel, corresponding to a complex carbide eutectic, reminiscent on the MI-1M friction machine designed for
of ledeburite and located along the grain boundaries. Vickers microhardness was measured on tribotechnical tests of cylindrical specimens
a microhardness meter mod. PMT-3M with a load of 200 gr. The measurement of the diagonals made of metallic materials and alloys, allowing
of the prints was carried out using an inverted metallographic microscope Metam LV-34 using to determine the tribotechnical indicators of
the automated analysis system "Micro-Analysis View". surfaces in conditions of sliding friction with
Table 4 shows the values of Vickers microhardness for a multi-layer hardened gradient boundary lubrication using the normalized
structure of a wear-resistant surface (Fig. 1). Table 5 shows the data on the hardness of steel method [5].
R18. Comparison of the data on hardness During tests with a specified load and
shows that in fact the surface layer of 45 sliding speed, a stationary cylindrical indenter
carbon steel is a gradient structure of tool Fig. 2. Microstructure of layer 1 (tungsten carbide particles) was pressed against the rotating cylindrical
steel R18. To determine the wear resistance and layer 2 (tungsten carbide mesh along the boundaries of surface of the sample partially immersed in
of a typical inexpensive structural 45 steel austenite grains.
with a gradient structure of the hardened the lubricant. To install the samples and the
surface, comprehensive comparative tests indenter, a scheme with replaceable holders
of the wear resistance of rather expensive was used, which provides self-alignment of
and technologically difficult to obtain the indenter relative to the test surface of the
modern wear-resistant coatings. sample on an intermediate spherical support
The tribotechnical indicators of the for the implementation of a linear contact.
outer cylindrical surfaces of samples made During the tests, using a system of sensors,
of steels R18 and 45 using the following the test time, load, coefficient of friction and
technologies were examined: linear wear were recorded continuously and
synchronously. Their numerical values were
displayed on a personal computer monitor.
To measure the moment of friction and load,
strain gauges were used. For continuous
Fig. 1. Surface structure of a steel sample hardened with tungsten measurement of wear during testing, a special
carbide. circuit was developed with the use of an Fig. 3. Results of tests of a sample of R18 steel after
inductive sensor, which makes it possible to volumetric quenching and low-temperature tempering.
Table 3. exclude the influence of the radial runout and
Energy dispersive analysis (Fig. 2), mass. %. thermal deformations of the test specimen on the measurement results.
According to the results of the analysis of the registered parameters, the following
points c Al Fe Cr Cu W total indicators of tribotechnical properties were determined:
1 16,8 - 4,0 - - 79,2 100,0 ● running-in time t0, h, defined as the time from the start of the test to the time when
2 7,6 - 6,4 14,7 - 71,3 100,0 the wear curve reaches the normal wear area;

3 3,3 - 84,2 - 2,9 9,6 100,0
4 3,6 - 83,6 - 2,7 10,1 100,0
5 15,1 0,6 71,5 - 4,0 8,8 100,0 Table 4.
6 11,8 0,7 76,9 - 2,1 8,5 100,0 Microhardness of the surface layer of 45 steel, hardened with tungsten carbide.
7 11,3 0,6 88,1 - - - 100,0 Microhardness of HV layer
layer 1 layer 2 layer 3 matrix

● volumetric hardening, low-temperature tempering (R18 steel); 741…846 546…633 431…525 304…332
● volumetric hardening, low-temperature tempering (R18 steel) + a coating with solid
solution hardening from compounds with different types of interatomic bonds of the Ti-Al-N Table 5.
system with a thickness of 3 microns, applied using PVD technology (in vacuum using an The hardness of steel R18 in the heat-treated state at elevated temperatures
electric arc plasma source and separation of a plasma flow) ; Test temperature ºC HV HRC
● volumetric hardening, low-temperature tempering (R18 steel) + coating with a multiphase 200 815 64
structure of the Mo-Cr-N system with a thickness of 3 microns, applied using PVD technology 400 755 62
(in vacuum using an electric arc plasma source and plasma flow separation); 500 712 60
● combined electromechanical treatment (CEMT) the formation of a surface layer implanted 550 661 58
with tungsten carbides on the surface of untreated 45 steel and subsequent electromechanical 600 615 56
hardening of the treated surface. 650 504 51

14 Stanochniy park Stanochniy park 15