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DIRECT INFLUENCE OF THE ELECTRON BEAM ON THE SURFACE OF THE MATERIAL (DIRECT MODIFICATION)

When exposed to intense pulsed electron beams, the material layer thickness that is equivalent to capture length in the material (from 10 to 100 microns), is very quickly heated up to phase transition temperature.

At the end of beam pulse the heated layer is rapidly cooled by the process of thermal conductivity in the depth of the material. As a result, the surface layer properties are changing:

• changing of the microstructure - grain size decreases from hundreds of microns to fractions of a micron, it is possible a transition to amorphous state, and a formation of nanostructures;

• changing of the phase composition, with the possible occurrence of metastable phases and compounds which can not be formed when the usual methods of heat treatment are applied;

• phase composition is being homogenized, for example, carbides in steels are being crushed and uniformly distributed.

Practical consequences of these changes are the enhancement of hardness, corrosion resistance and wear resistance of the materials surface, reducing the coefficient of friction, increasing the dynamic strength of products.

CHANGING OF THE SURFACE LAYER MICROSTRUCTURE

Stainless steel 12Х18Н10Т

Микрогеометрия поверхности до обработки электронным пучком Микрогеометрия поверхности после обработки электронным пучком
Microgeometry of the surface before the treatment by an electron beam (left) and after treatment (right)

Protective coating NiCoCrAlY

Microgeometry of the cross section of the coating after electron beam treatmentлектронным пучком Microgeometry of the surface of the coating after electron beam treatment
Microgeometry of the cross section of the coating after electron beam treatmentлектронным пучком Microgeometry of the surface of the coating after electron beam treatment

IMPROVING OF MICROHARDNESS IN AUTOMOTIVE INDUSTRY

Steel gradeThe energy of the electrons, keVThe pulse duration, microsec.The thickness of the layer, micronsHardness before treatment, kg/mm2Hardness after treatment, kg/mm2
40ХН2МА 150 20 25 170 350
50Х20Н4АГ9 150 20 40 250 800
40Х9С2 100 8 18 300 700
40Х9С2 140 14 12 300 500
08КП 180 6 22 200 1100
08КП 150 20 50 200 700
Ст6СП 60 35 12 250 700
Ст6СП 180 8 25 250 550

График

IMPROVING OF WEAR RESISTANCE OF A MACHINE ENGINES’ DETAILS

График

Details wear (mass loss) after engine test (18 runs, 2 hours per each run)

DetailTraditional technology of hardening, mgAdditional beam treatmentImprovement coefficient of wear resistance
Follower 3,79 0,87 4,3
Tappet 2,04 0,88 2,3

The wear resistance of gears treated with electron beam and without electron beam treatment. Improvement after electron beam treatment from 5 to 10 times.

График3

MODIFICATION OF OXIDE LAYER MICROSTRUCTURE ON THE SURFACE OF THE PROTECTIVE COATING

Pulsed electron-beam treatment dramatically reduces the initial rate of protective coating oxidation that decreases the thickness of the oxide layer by 2-3 times. The difference between oxide layer growth rate on the polished surface and on the beam treated surface of the protective coating depend on different microstructure of the oxide layer.

хрень1 хрень2
The microstructure of the oxide layer on the surface of protective coating MeNiCrAlY after polishing (left) and after pulsed electron beam treatment (right). Tests duration - 200 hours at 950C.

 
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