International Scientific-Technical and Production Journal
March
2011
#3
English translation of the monthly «Avtomaticheskaya Svarka» (Automatic Welding) journal published in Russian since 1948
Founders: E.O. Paton Electric Welding Institute of the NAS of Ukraine
International Association «Welding»
Editor-in-Chief B.E.Paton
Publisher: International Association «Welding»
CONTENTS
Editorial board:
Yu. <...> V. FALCHENKO, A.N. MURAVEJNIK,
T.V. MELNICHENKO and L.V. PETRUSHINETS
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
The effect of nanolayered interlayers Ti/Al, Ni/Ti and Ni/Al on structure of the diffusion bonds made in vacuum on
γ-TiAl base alloy was studied. <...> It is shown that when using the nanolayered interlayers of a composition differing from
that of the base alloy it is necessary to conduct homogenising annealing to lower the degree of chemical heterogeneity
in the bonding zone. <...> K e y w o r d s : diffusion bonding in vacuum, intermetallic titanium-aluminium alloy based on γ-TiAl, nanolayered interlayer,
homogenising annealing, joint, heterogeneity, structure, microhardness
Titanium aluminides and alloys on their base belong
to a new class of light heat-resistant materials, which
are intended for operation at a temperature of 700—
1100 °C, that is much higher than the service temperature of modern titanium superalloys (T ≤ 600 °C). <...> The TiAl nanocrystals with a higher hardness than that of the base metal
form in the interlayers during deposition of a film. <...> It is shown in study [3] that the optimal parameters
for diffusion bonding of γ-TiAl alloys through the
nanolayered interlayer Ti/Al produced by vacuum
deposition are as follows: Tbond = 1200 °C, P = 10 MPa,
and tbond = 20 min. With these parameters the bonding
zone is free from pores and cracks. <...> Microstructure and chemical composition of the
base metal and bonds were analysed by using optical
microscope «Neophot-32», as well as scanning microscope «CamScan» equipped with energy-dispersive
system «Energy 200» for local analysis. <...> A fragment of the diffraction pattern of the γ-TiAl alloy is shown in Figure 1. <...> The alloy
consists of homogeneous, practically equiaxed grains
approximately 60—120 μm in size, having the γ- and
α2-phase lamellae of a certain orientation inside them
(Figure 2 <...>
The_Paton_Welding_Journal_№3_2011.pdf
International Scientific-Technical and Production Journal
March
2011
# 3
English translation of the monthly «Avtomaticheskaya Svarka» (Automatic Welding) journal published in Russian since 1948
Editor-in-Chief B.E.Paton
Yu.S.Borisov V.F.Khorunov
A.Ya.Ishchenko I.V.Krivtsun
B.V.Khitrovskaya L.M.Lobanov
V.I.Kirian A.A.Mazur
S.I.Kuchuk-Yatsenko
Yu.N.Lankin I.K.Pokhodnya
V.N.Lipodaev V.D.Poznyakov
V.I.Makhnenko K.A.Yushchenko
O.K.Nazarenko A.T.Zelnichenko
I.A.Ryabtsev
CONTENTS
SCIENTIFIC AND TECHNICAL
. and
. and
N.P.Alyoshin (Russia)
U.Diltey (Germany)
Guan Qiao (China)
D. von Hofe (Germany)
V.I.Lysak (Russia)
N.I.Nikiforov (Russia)
B.E.Paton (Ukraine)
Ya.Pilarczyk (Poland)
G.A.Turichin (Russia)
Zhang Yanmin (China)
A.S.Zubchenko (Russia)
V.N.Lipodaev, V.I.Lokteva
A.T.Zelnichenko (exec. director)
A.A.Fomin, O.S.Kurochko,
I.N.Kutianova, T.K.Vasilenko
N.A.Dmitrieva
D.I.Sereda, T.Yu.Snegiryova
. Diffusion
bonding of γ-TiAl base alloy in vacuum by using nanolayered
interlayers ........................................................................................... 2
. Fracture surface morphology at fatigue
of MIG-welded joints of AMg6 alloy ...................................................... 7
. and
.
Peculiarities of intergranular mass transfer of gallium in
aluminium alloy during solid phase activation of surfaces being
joined ................................................................................................. 13
. Conditions for formation of defect-free welds in
narrow-gap magnetically controlled arc welding of low titanium
alloys .................................................................................................. 16
. and
. and
INDUSTRIAL
. and
. Control of arc ignition during excitation of electroslag
process .............................................................................................. 26
. and
. Evaluation of stability of the
flashing process in flash butt welding .................................................. 29
. Selection of the groove shape for repair of
State Registration Certificate
KV 4790 of 09.01.2001
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© PWI, International Association «Welding», 2011
through cracks by multilayer electroslag welding ................................. 32
. and
. Improvement of the quality
of welded assembly for branchpipe cutting into the wall of oil
storage tank ....................................................................................... 36
. and
. Shielding
materials and personal gear for welder protection from
magnetic fields ................................................................................... 38
BRIEF INFORMATION
News .................................................................................................. 44
Developed at PWI ........................................................................... 6, 21
Abstracts of works on innovation projects of the NAS of
Ukraine ............................................................................................... 43
.
Monitoring of corrosion of pipelines of cooling system of
automobile gas-filling compressor stations .......................................... 19
. Development of a procedure
for selection of parameters of strip electrode surfacing with
mechanical forced transfer of liquid metal ........................................... 22
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Стр.1
DIFFUSION BONDING OF γ-TiAl BASE ALLOY
IN VACUUM BY USING NANOLAYERED INTERLAYERS
G.K. KHARCHENKO, A.I. USTINOV, Yu.V. FALCHENKO, A.N. MURAVEJNIK,
T.V. MELNICHENKO and L.V. PETRUSHINETS
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
The effect of nanolayered interlayers Ti/Al, Ni/Ti and Ni/Al on structure of the diffusion bonds made in vacuum on
γ-TiAl base alloy was studied. It is shown that when using the nanolayered interlayers of a composition differing from
that of the base alloy it is necessary to conduct homogenising annealing to lower the degree of chemical heterogeneity
in the bonding zone.
Keywords: diffusion bonding in vacuum, intermetallic titanium-aluminium
alloy based on γ-TiAl, nanolayered interlayer,
homogenising annealing, joint, heterogeneity, structure, microhardness
Titanium
aluminides and alloys on their base belong
to a new class of light heat-resistant materials, which
are intended for operation at a temperature of 700—
1100 °C, that is much higher than the service temperature
of modern titanium superalloys (T ≤ 600 °C).
The interest in titanium aluminides is caused by their
high potential for application in aerospace engineering
instead of titanium and nickel superalloys.
Studies [1, 2] investigated joinability of titanium
aluminides (Ti—45 at.% Cr—2 at.% Nb) when using
the Ti—Al system nanolayered interlayers of the Ti—
(48—50) at.% Al composition, which were deposited
on the mating surfaces by magnetron sputtering.
Thickness of the interlayers was 2.0—2.5 μm, thickness
of the individual layers being 4 nm. The TiAl nanocrystals
with a higher hardness than that of the base metal
form in the interlayers during deposition of a film.
The authors of the above studies consider the following
parameters of the process to be the optimal ones: bonding
temperature Tbond = 1000 °C, pressure P = 50 MPa,
and bonding time tbond = 1 h.
It is shown in study [3] that the optimal parameters
for diffusion bonding of γ-TiAl alloys through the
nanolayered interlayer Ti/Al produced by vacuum
deposition are as follows: Tbond = 1200 °C, P = 10 MPa,
and tbond = 20 min. With these parameters the bonding
zone is free from pores and cracks.
No investigation results on the possibility of using
other compositions of nanolayered interlayers are
available in the literature.
The purpose of this study was to investigate peculiarities
of formation of permanent bonds on the γ-TiAl
base alloy by using nanolayered interlayers of the
Ti/Al, Ni/Ti and Ni/Al systems in the form of foils
15—30 μm thick, produced by electron beam evaporation
and vapour-phase deposition in vacuum [4, 5].
The foils consist of alternating nanolayers of the com2
ponents,
in which solid-phase reactions of synthesis
of intermetallics take place during heating.
The following interlayers were chosen for bonding
of samples of alloy Ti—48 at.% Al—2 at.% Nb—2 at.%
Mn: Ti/Al (Ti—38 at.% Al), Ni/Ti (Ti—44 at.% Ni)
and Ni/Al (Al—46 at.% Ni).
Diffusion bonding of the 10 Ч 10 Ч 6 mm samples
of intermetallic Ti—48 at.% Al—2 at.% Nb—2 at.% Mn
(below referred to as γ-TiAl) was performed by using
unit U-394. The electron beam heater was employed
as a heat source. The mating surfaces were preliminarily
prepared by removing the cold worked layer
with a diamond wheel, and then by degreasing. Bonding
was carried out under the following conditions:
heating temperature Th = 1200 °C, heating time th =
= 20 min, P = 20 MPa, and vacuum in the working
chamber at a level of 1.33⋅10—3 MPa.
Microstructure and chemical composition of the
base metal and bonds were analysed by using optical
microscope «Neophot-32», as well as scanning microscope
«CamScan» equipped with energy-dispersive
system «Energy 200» for local analysis. Phase composition
was evaluated by the X-ray diffraction analysis
method using diffractometer DRON-3 in CuKα
radiation.
Microhardness of the samples was measured
with meter PMT-3 under a load of 0.1—0.5 N.
Results of X-ray diffraction phase analysis show
that the γ-TiAl alloy in the initial state contains two
phases – TiAl (γ-phase) and Ti3Al (α2-phase). The
volume content of the α2-phase in the alloy, with
respect to the γ-phase, is 7 %. A fragment of the diffraction
pattern of the γ-TiAl alloy is shown in Figure
1.
As revealed by metallography, the alloy in the
initial state has a fully lamellar structure. The alloy
consists of homogeneous, practically equiaxed grains
approximately 60—120 μm in size, having the γ- and
α2-phase lamellae of a certain orientation inside them
(Figure 2).
It is noted in study [6] that normally the α2-phase
is present in the lamellar structure in the form of thin
© G.K. KHARCHENKO, A.I. USTINOV, Yu.V. FALCHENKO, A.N. MURAVEJNIK, T.V. MELNICHENKO and L.V. PETRUSHINETS, 2011
3/2011
Стр.2