National Technical University of Ukraine – Kyiv Polytechnic Institute, 37, Peremogi ave., Kyiv, 03056,
Ukraine, Ph.: +38 044 4890164, E-mail: kvas69@rambler.ru
*Institute of High Current Electronics SB RAS, 2/3., Akademichesky ave., Tomsk, 634055, Russia
**The E.O. Paton electric Welding Institute of the NAS of Ukraine, 11, Bozhenkastr., Kyiv, 03680, Ukraine
***Admiral Makarov National University of Shipbuilding, 9, Geroev Stalingrada ave., Mykolaiv, 54025,
Ukraine, Ph.: +38 0512 431174, F.: +38 0512 421081, E-mail: welding@nuos.edu.ua
The Application of High-Current Low-Energy
Electron Beam
for Diffusion Welding and Brazing of Materials.
Abstract – The structure and strength of the surface coating layers of iron, stainless
steel and heat-resistant alloy treated by high-current low-energy electron beam have
been considered. The microstructure and properties of diffusion bonded and brazed
joints have been studied.
V.V. Kvasnytskyy, N.N. Koval*, Yu.F. Ivanov*, L.I. Markashova**, V.D. Kuznetsov,
V.F. Kvasnytskyy***
Diffusion welding (DW) is the effective method of bond of materials and belongs to
method of welding with pressure. In pressure welding a very important issue is surface
condition. Presence on the surface of adsorbed gases and oxide films requires that surfaces
be activated in order to form bonds between atoms of materials being joint. To activate
surfaces there were proposed: cyclic loading, use of ultra dispersed powders, intermediate
gaskets (may be fusible and infusible) and many other methods that do not always prove to
be effective. Often solders are used as fusible gaskets, which requires placing of solders
and complicates assembly of articles. There are also problems in manufacture of modern
solders. Therefore, search of new diffusion welding and brazing technologies is vital.
Purpose of this work is to study impact of surfaces, modified with high-current lowenergy electron beams, on formation of joints in diffusion welding of iron with stainless
steel and heat-resistant alloys and brazing of heat-resistant nickel alloys.
Fig. 1 Microstructure of
welded joint during
traditional DW of
alloyЧС88У-ВИ, ×800
a
b
Fig. 2. Microstructure of modified layer of steel grade 10895 (a, ×250) and its
fine structure (b, ×28000).
a
b
Fig. 3. Fine structure of modified layer of steel grade 12Х18Н10Т (a, ×20000)
and nickel - base alloy ЧС88У-ВИ (b, ×30000).
Microhardness, MPa
Condition of
metal
Steel of
10 895
Steel of
12Х18Н10Т
Alloy
ЧС88У-ВИ
Parent metal
(condition
of delivery)
1180 ...1240
1210
1610...1920
1810
3290...3410
3320
Modified
1950...2290
2100
1820...2100
1980
2440...2830
2660
Dз~1,5 мкм
Dз~15 мкм
Fig. 4. Microstructure of modified layer of steel grade 10895 × 250
7
Fig. 5. Microstructure of
welded joint of steel grades
12Х18Н10Т and 10895 with
modified surfaces: ×400
b, х20 000
а
Fig. 6. Microstructure of DW joint of alloy
ЧС88У-ВИ with modified surfaces: (a×400), fine
structure (b, c)
c, х37 000
9
a, х 20 000
b, х 37 000
Fig. 7. Fine structure of DW joint with modified layer of steel grade 10895
and 12Х18Н10Т.
10
Fig.8. Change of TKLD by heating at a speed of
28 °С/с (1, 2), 2 °С/с (4,5), 1 °С/с (3) alloy of ЧС88У-ВИ, driving complete heat treatment
(1,3,4) and driving hardening in water (2,5)
11
a
b
c
d
Fig. 9. Epures of plastic deformation εx (а), εy (b), εху (c) and ε ecv (d) at the temperature of
1050°С (1), 1075°С (2), 1100°С (3), 1125°С (4) and 1150°С (5)
12
, %
0,40
0,35
0,30
0,25
0,20
0,15
0,10
0,05
0
y, %
0
-0,05
-0,10
-0,15
-0,20
-0,25
-0,30
1
2
3
а
4
5
1
2
3
b
4
5
экв, %
0,40
0,35
0,30
0,25
0,20
0,15
0,10
0,05
0
1
2
3
3
5
c
Fig. 10. Fields of plastic deformation εy (а), εxy (b) and εecv (c) at heating of DW bond of alloy
ЧС88 in different structural conditions: at a temperature 1050 °С (1), 1075 °С (2), 1100 °С (3),
1125 °С (4) и 1150 °С (5) (above – heat-treated, down is the hardened metal)
13
b
а
Fig. 11. Surface of sample (a) and
spectrum on the elements of the
alloyed (b) and covered (c) surfaces
layer on the alloy of ЧС88У-ВИ
c
14
aа
b
×600
б
×1550
Concentration of Zr, % mass
h3,5…4мкм
1
7
Distance , micrometer
dг
×3100
c в
Fig. 12. Morphology of cross-sectional (a, b, c) and distribution of Zr (d) in a alloy of
1
2
3
4
5
6
7
2 and depths of the
ЧС88У-ВИ
after
alloying
of
Zr
(10
imp.
at
density
of
energies
25
J/sm
51,57
54,6
55,76
56,95
57,96
57,19
57,58
Ni
15
9,36
9,74
9,61 10,27alloyed
11,21 11,08
10,87
bench
of 4 micrometer
Co
Cr
13,96
14,66
15,42
15,57
15,16
15,79
15,75
косой шлиф
bб
×600
h10мкм
1
7
Concentration of Zr, % mass
aа
×1550
Distance , micrometer
dг
c в
×3100
Fig. Рис.3
13. Morphology of cross-sectional (a, b, c) and distribution of Zr (d) in a alloy of
1
2
3
4
5
6
7
8
9
10
11
ЧС88У-ВИ
after
alloying
of Zr
(10
imp.
at density
of energies
2512J/sm213and depths of the
16
alloyed bench of 8 micrometer
а
b
d
c
Fig. 14.Surface of heatproof alloys of ЧС88У-ВИ (a), Inconel 718 (b), brazing (c, d)
17
а
c
b
d
Fig. 15. Microstructure of bond of alloy of ЧС88У-ВИ by alloying of Zr
δ=1,0 micrometer: (a, b) - alloyed two of bond surface, (c, d) - alloyed one of bond surface
18
Conclusions:
1. Comparison of diffusion welding of steel grades 10 895 and 12Х18Н10Т with
different preparation of surfaces showed, that formation of bonded joint is most
effectively conduced by modification of both surfaces to be joint. If only one
surface is to be modified, it should be surface of α-iron, whose energy of crystalline
structure defects is much greater than that of γ-Fe.
2. Positive effect of surface modification of dispersion-strengthened nickel alloy is
caused by both modification effect (highly dispersive structure, dislocations
density, etc.) and build up of high level of strains in contact of modified (hardened)
layer and alloy with excessive phase producing plastic deformations in their contact
zone, which is confirmed by deformation strips in the butt joint area. At this, more
preferable is bonded joint of modified and non-modified surfaces.
3. It was established for the first time that impact of HCLEEB permits to braze surface
of heat-resistant alloys with elements reducing melting temperature of surface layer,
specifically with Zr, Hf, Nb, with bringing of introduced element concentration
close to concentration in solders by changing thickness of its previously applied
layer, energy density in electron beam, duration and number of pulses.
4. Brazed layer functions not only as solder but conduces to development of plastic
deformations and formation of common grains in the joint.
5. Modification of surface layer of materials to be fused by change of its structure, level
of structural strains, 3-d category strains, brazing with elements reducing welding
temperature, is an effective means to raise quality and simplify technology of
diffusion welding.