O. LYUBIMOVA et al.: CHARACTERISATION OF THE MECHANICAL AND CORROSIVE PROPERTIES ...
95–100
CHARACTERISATION OF THE MECHANICAL AND CORROSIVE
PROPERTIES OF NEWLY DEVELOPED GLASS-STEEL
COMPOSITES
KARAKTERIZACIJA MEHANSKIH IN KOROZIJSKIH LASTNOSTI
NOVO RAZVITIH KOMPOZITOV STEKLO-JEKLO
Olga Lyubimova1, Ekaterina Gridasova2, Alexander Gridasov2, Gerrit Frieling3,
Martin Klein3, Frank Walther3
1Department of Mechanics and Mathematical Modeling, Far Eastern Federal University (FEFU), Vladivostok, Russia
2Department of Welding Production, Far Eastern Federal University (FEFU), Vladivostok, Russia
3Department of Materials Test Engineering (WPT), TU Dortmund University, Dortmund, Germany
gerrit.frieling@tu-dortmund.de
Prejem rokopisa – received: 2014-12-17; sprejem za objavo – accepted for publication: 2015-02-17
doi:10.17222/mit.2014.305
This paper presents a preliminary research about a newly developed glass-steel composite created with diffusion welding of
glass (C49-1) and carbon steel (St3sp). The main conclusions on the process of forming a diffusion zone during the welding of
glass and steel are made. The results of quasi-static and cyclic mechanical tests and corrosion investigations are presented and
interpreted on the basis of the microstructure developed during diffusion welding and described in this article.
Keywords: hardening of glass, diffusion welding, glass-steel composite material, tensile tests, cyclic tests, fatigue, corrosion,
microstructure
^lanek predstavlja uvodne raziskave novo razvitega kompozita steklo-jeklo, izdelanega z difuzijskim varjenjem stekla (C49-1)
in ogljikovega jekla (St3sp). Postavljeni so glavni zaklju~ki o postopku nastajanja difuzijske cone med varjenjem stekla in jekla.
Na osnovi razvoja mikrostrukture pri difuzijskem varjenju so predstavljeni in razlo`eni rezultati kvazi stati~nih, cikli~nih
mehanskih in korozijskih preizkusov.
Klju~ne besede: utrjevanje stekla, difuzijsko varjenje, steklo-jeklo kompozitni material, natezni preizkusi, cikli~ni preizkusi,
utrujenost, korozija, mikrostruktura
1 INTRODUCTION
Glass shows a diverging behavior for different kinds
of deformation. On the one hand, it has a relatively high
compressive strength; however, on the other hand, it has
a relatively low tensile strength. The values for the
compressive strength of glass are in the range of
500–1250 MPa. So, when working in the compressive
mode, glass can compete with the structural-grade
carbon steel. At the same time, the tensile strength of
glass is much lower: 30–50 MPa.1,2 This is due to the fact
that the strength of glass is largely dependent on the state
of its surface. The most well-known methods for the
hardening of glass allow the creation of compressive
stresses in the surface layers of glass (glass hardening,
ion exchange, surface crystallization) and surface hard-
ening (mechanical polishing, removal of the defective
surface layer by etching the glass, application of protec-
tive coatings). It is proposed to study the methods, which
allow the hardening of glass by eliminating not only the
surface micro-defects but also the internal micro-defects,
as well as providing insulation from the effects of the
environment.3,4 As a result, the composite material would
be larger and stronger. Diffusion welding5 is used widely
for joining the elements of simple configuration. It finds
a wide application in electronics, aviation and other
industries. However, despite the extensive study of the
mechanism interaction of various materials during the
diffusion welding, a general theory about the relationship
between glass and metal has not yet been developed.
The aim of this study is to investigate the mechanical
and corrosive properties of this newly developed glass-
steel composite material. Therefore, quasi-static, cyclic
and potentiodynamic polarization tests are carried out.
Furthermore, light microscopic studies are performed to
build the basis for microstructure-oriented assessments
of the mechanical and chemical results.
2 EXPERIMENTAL METHODS
2.1 Processing of glass-metal composites
The rod was made as illustrated in Figure 1a. The
mobile cover (3) provides holes for gas outlets and the
possibility for a forward movement along the longitudi-
nal axis of the shell (2). The movement of the cover (3)
is dependent on the shrinkage of the rod (1) during the
heating process.
The technological regime (pressure during diffusion
bonding p = 0.25 MPa) is divided into six stages (Figure
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UDK 669.018.9:620.17:620.193 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 50(1)95(2016)
1b). In the first step, which corresponds to the interval
(0, t1), the composite rod is heated from T0 = 20 °C to the
temperature of welding Tw (around 800 °C). Given the
limited deformation ability of glass to produce a lasting
connection, Tw = Tg, where Tw = (0.4 … 0.6) Tm, with Tg
as the temperature of glass softening and Tm as the tem-
perature of the melting metal from which the shell (2)
was made. In the interval (t1, t2), Tw is maintained,
providing a reliable connection between glass and steel.
It is then cooled down to the temperature of annealing
Trel. To reduce the initial stress, the annealing is carried
out in the interval (t3, t4). This is a necessity at such tem-
peratures, as the viscosity is still quite low, for example,

"= 1012 Pa s; the residual stresses are removed after
15 min and, with 
" = 1013.5 Pa s, after 4 h. In the interval
(t4, t5), the required cooling is carried out up to T1, with a
rate of 3–5 K/min. After 
’  1015 Pa s, the residual
stresses in the glass do not disappear so that at the last
stage – the sixth stage – a more rapid cooling at 15–25
K/min is possible.
2.2 Microscopy
The microstructure of the hybrid material was
investigated with light microscopy. Therefore, slices of
the specimen were cut off using a cutting wheel. Before
using a microscope, these slices were cold mounted,
ground and polished.
2.3 Tensile and fatigue testing
The quasi-static properties with respect to the com-
pression, tension and torsion of the glass-metal compo-
site, consisting of chemical-laboratory glass brand C49-1
(3C-5Na) and carbon steel St3sp, were determined using
a tensile testing system (Shimadzu, 1000 kN, UH-I)
(Figure 2). Glass C49-1 has the following chemical
composition: 67.5 % SiO2; 20.3 % B2O3; 3.5 % Al2O;
8.7 % Na2O.
Carbon steel St3sp comprises the following quantities
of the alloying elements: 0.14–0.22 C; 0.15–0.30 Si;
0.4–0.65 Mn; 0.05 S; 0.04 P; 0.3 Cr; 0.3 Ni;
0.3 Cu; 0.08 As; 0.01 N.
The geometries of the specimens and their dimen-
sions are shown in Figure 3 and Table 1, respectively.
Table 1: Geometrical characteristics of the specimens, in mm
Tabela 1: Geometrijske zna~ilnosti vzorcev, v mm
d l0 l D h r lg dg hg
10.0 100.0 105.0 16.0 10.0 3.0 105.0 7.5 30.0
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96 Materiali in tehnologije / Materials and technology 50 (2016) 1, 95–100
Figure 2: Tensile testing system Shimadzu 1000 kN UH-I
Slika 2: Natezni preizku{evalni sistem Shimadzu 1000 kN UH-I
Figure 1: a) Schematic view of a composite rod: 1 – rod of glass
C49-1 (3C5Na), 2 – outer shell of steel St3sp, 3 – mobile cover, b)
temperature welding: T – temperature welding, lg 
 – logarithm of the
dynamic viscosity of glass
Slika 1: a) Shematski prikaz kompozitne palice: 1 – palica iz stekla
C49-1 (3C5Na), 2 – zunanji ovoj iz jekla St3sp, 3 – premi~ni pokrov,
b) temperaturno varjenje: T – temperature varjenja, lg 
 – logaritem
dinami~ne viskoznosti stekla
Figure 3: Geometries of the specimens for: a) compression and b) ten-
sile tests
Slika 3: Geometrija vzorcev za: a) tla~ni preizkus in b) natezni preiz-
kus
For the investigation of the fatigue behavior, load-
increase tests and constant-amplitude tests were
performed.6,7 The specimens were subjected to a stress
ratio of R = –1 and a frequency of f = 10 Hz using sinu-
soidal load-time functions at room temperature. For the
dynamic tests, the specimen geometry shown in Figure
3b was used. In order to measure the total strain and to
determine the plastic-strain amplitude, an extensometer
was attached to the specimen.
Figure 4 shows a specimen mounted onto the servo-
hydraulic testing system (Shimadzu, 20 kN, EHF-LV20)
with the attached extensometer. The testing system has
the maximum load capacity of 20 kN and the extenso-
meter has a range of ± 4.0 % of the total strain. The
fatigue strength of the glass-metal composite rod for the
ultimate number of cycles Nlimit = 2·106 was estimated
with a stepwise load-increase test according to the
measured material response and afterwards validated
with constant-amplitude tests.
2.4 Corrosion testing
The corrosion behavior of the St3sp steel and of the
hybrid interface was investigated with potentiodynamic
polarization measurements in a 0.1 mol L–1 NaCl so-
lution at pH7; the pH values were adjusted using a 0.1
mol L–1 KOH solution. A standard three-electrode sys-
tem, consisting of a saturated calomel electrode (SCE) as
the reference electrode and a graphite electrode as the
counter electrode, was used for the measurements8. As
the working electrodes, the St3sp steel and the cross-sec-
tion of a round specimen (Figure 3b) for fatigue testing
were used. The specimens were abraded with emery
paper of 18–5 μm. Then, a copper wire was attached to
the specimens and the whole specimens, except for their
front sides, were embedded in the epoxy resin. Before
each polarization measurement, the electrolyte was
purged for 30 min with argon and afterwards the open-
circuit potential was measured for 30 min. The measure-
ments were conducted using a potentiostat (Gamry,
PCI4300) at a scanning rate of 0.1 mV/s. The experi-
mental set-up of the potentiodynamic-polarization
measurements is shown in Figure 5.
3 RESULTS AND DISCUSSION
3.1 Microstructure
The St3sp steel was found to have a ferritic structure
with around 8 % of pearlite. After polishing and analyz-
ing the border-welding zones of the samples, there were
still no visible cracks or voids. The analysis of micro-
sections showed the presence of a full contact without
cracks or spills in the welding zone (Figure 6). The
microscopic examination of the welding zone clearly
shows a development of the interaction at the boundary
of the contact. A bright zone in the glass confirms this
development. The results of the spectral analysis indicate
a penetration of cations into the glass to a depth of 30
microns and more. This is in accordance with the results
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Materiali in tehnologije / Materials and technology 50 (2016) 1, 95–100 97
Figure 4: Fatigue testing system: a) overview and b) detail
Slika 4: Sistem za preizku{anje utrujanja: a) pregled in b) detajl
Figure 6: a) Micrograph of the welded joint between metal and glass,
b) micrograph of the cross-section
Slika 6: a) Posnetek podro~ja zvarjenega spoja med kovino in ste-
klom, b) posnetek preseka
Figure 5: Potentiodynamic-polarization measurement set-up
Slika 5: Sistem za merjenje potenciodinami~ne polarizacije
of the corrosion tests, which also indicated the formation
of the glass-metal phase.
Figure 7 shows the grains in the transition area
between steel and glass. It is apparent that the grain size
of the ferritic structure in close vicinity of the glass is
smaller than at bigger distances. The explanation for this
behavior has not been found yet, but it will be a topic of
further investigations of this glass-steel composite
material.
3.2 Deformation behavior
By performing the compression, tensile and torsional
tests, the quasi-static properties of the selected glass, the
steel and the glass-steel composite were determined. The
stress-strain curves for compression and tension of the
composite material are depicted in Figure 8. The results
for different materials and tests are shown in Tables 2
and 3.
The maximum compressive stress of the composite
material is more than 13 times higher than the maximum
compressive stress of the C49-1 glass and it is twice as
high as for the St3sp carbon steel. The maximum tensile
stress of the composite sample is twice as much as that
of glass and half of that of carbon steel. The Young’s
modulus and shear modulus of the composite have
intermediate values of the modules of the base materials,
glass and steel.
Table 2: Mechanical characteristics of base materials and glass-steel
composite rod
Tabela 2: Mehanske zna~ilnosti osnovnih materialov in kompozitne
palice steklo-jeklo
Fmax/kN max/MPà
Glass (C49-1) compressivestrength 2.55 55.00
Glass (C49-1) tensile strength 3.40 77.00
Steel (St3sp) compressivestrength 30.05 389.20
Steel (St3sp) tensile strength 29.00 368.96
Composite
glass-steel
compressive
strength 58.50 745.00
Composite
glass-steel tensile strength 12.70 162.00
Table 3: Mechanical characteristics of base materials and glass-steel
composite rod
Tabela 3: Mehanske zna~ilnosti osnovnih materialov in kompozitne
palice steklo-jeklo
Glass (C49-1) Steel (St3sp) Compositeglass-steel
Young’s
modulus, (MPà) 0.73·10
5 2.10·105 1.40·105
Shear modulus,
(MPà) 0.30·10
5 0.80·105 0.56·105
3.3 Fatigue beahvior
For an evaluation of the cyclic-deformation behavior
and for an estimation of the fatigue strength, a stepwise
load-increase test was performed with a glass-metal
composite specimen as depicted in Figure 9. During this
test, the plastic-strain amplitude was measured as the
parameter of the material reaction, which characterizes
the proceeding fatigue damage as the basis for the esti-
mation of the fatigue strength.9 The estimation of the
fatigue strength was validated with constant-amplitude
tests, whose lifetimes (the number of cycles to failure)
are shown with the S-N curve.
Starting at a,start = 6.4 MPa, the stress amplitude was
increased by 6.4 MPa each 104 cycles until failure. The
plastic-strain amplitude a,p increases slightly within the
first nine steps, but remains almost constant within each
step. In the tenth step, there is a visible increase com-
pared to the ninth step, but the plastic-strain amplitude
still does not increase within the step. This is different
for the eleventh step at the stress amplitude of 70.4 MPa.
In the twelfth step, there is a considerable increase of the
O. LYUBIMOVA et al.: CHARACTERISATION OF THE MECHANICAL AND CORROSIVE PROPERTIES ...
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Figure 7: Micrograph of the grains in the transition area between steel
and glass
Slika 7: Posnetek zrn v jeklu v prehodnem podro~ju v steklo
Figure 8: Stress-strain curve of the glass-metal composite for: a) com-
pression and b) tension
Slika 8: Krivulja napetost – raztezek kompozita steklo-kovina pri: a)
tla~nem in b) nateznem preizkusu
plastic-strain amplitude and, finally, there is an exponen-
tial increase in the thirteenth step.
As the fatigue strength is linked to the first increase
in the material-reaction quantity within one step,9 the
estimate from this load-increase test for the endurance
limit is 70 MPa. This estimation was validated with the
constant-amplitude tests with Nlimit = 2·106 as the
ultimate number of cycles. Ten tests with different stress
amplitudes were conducted and the results are shown as
an S-N curve in Figure 10. The highest stress amplitude
used is 127 MPa, which is close to the tensile strength of
162 MPa (Table 3) for the glass-metal composite. The
specimen with a load amplitude of 64 MPa reached the
ultimate number of cycles without fracture.
For this set of specimens, the modified Basquin
equation was found to be a = 245 MPa (Nf)–0.09.
If the estimation of the fatigue strength from the
load-increase test (70 MPa) is compared to the highest
stress amplitude without failure (64 MPa), it becomes
apparent that the estimation on the basis of the
plastic-strain amplitude is a very suitable tool for this
composite material, with only one specimen. The stress
amplitude of the highest run-out specimen is about 40 %
of the tensile strength of the composite material.
3.4 Corrosion behaviour
Figure 11 shows the Tafel plots for the steel jacket
and the hybrid interface between glass and steel. The
steel jacket shows a marginally less noble corrosion
potential Ecorr than the hybrid interface. However, the
corrosion current density icorr (i.e., the corrosion rate) of
the glass-metal joint is approximately four times higher
than that of the metal jacket. Consequently, the welding
of glass and metal influences the corrosion resistance,
suggesting that a glass-metal phase is formed through the
welding process.
4 CONCLUSIONS
The formation of a glass-metal phase was determined
with micrographs and corrosion tests. Furthermore, a
dependency of the steel grains as a function of the dist-
ance to the transition zone was found. The newly deve-
loped glass-metal composite material has quasi-static
properties, comparable to those of the St3sp steel. Using
a stepwise load-increase test and constant-amplitude
tests, the endurance limit of the composite was evaluated
as 70 MPa. This value is about 40 % of its tensile
strength. The corrosion rate of the composite material
was ascertained to be four times higher than the corro-
sion rate of the St3sp carbon steel.
This glass-metal material has potential applications,
especially for compressive loads, for example, in civil
engineering. The analysis of the glass-metal phase, the
examination of the grain-size distribution in the carbon
steel near the transition zone as well as the mechanical
investigations with a superimposed corrosive impact
during the cyclic testing, i.e., corrosion-fatigue investi-
gations, are planned as the further investigation steps.
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Materiali in tehnologije / Materials and technology 50 (2016) 1, 95–100 99
Figure 11: Tafel plots of the metal jacket and glass-steel composite
Slika 11: Taflov diagram kovinskega ovoja in kompozita steklo-jeklo
Figure 9: Stepwise load-increase test with a glass-metal composite
Slika 9: Preizkus stopni~astega nara{~anja obremenitve kompozita
steklo-jeklo
Figure 10: S-N curve for glass-steel composite
Slika 10: S-N-krivulja za kompozit steklo-jeklo
Acknowledgements
The study was supported by the Federal Program
"Nanosystems" Activity 1.2, contract ¹ 14.575.21.0009,
unique identifier ASR RFMEFI57514X0009.
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