Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel
High-strength low-alloy steel 50 mm thick is well joined by metal-active gas double-sided doublepower arc welding, which does not require preheating, postheating, and back chipping. Mechanical properties of the weld seam and base metal were investigated. Results of the tensile test indicate that the...
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| Опубліковано в: : | Проблемы прочности |
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Інститут проблем міцності ім. Г.С. Писаренко НАН України
2015
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| Цитувати: | Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel / Y.X. Chen, C.D. Yang, X.J. Wang, S.B. Chen // Проблемы прочности. — 2015. — № 1. — С. 187-193. — Бібліогр.: 8 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859731047080525824 |
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| author | Chen, Y.X. Yang, C.D. Wang, X.J. Chen, S.B. |
| author_facet | Chen, Y.X. Yang, C.D. Wang, X.J. Chen, S.B. |
| citation_txt | Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel / Y.X. Chen, C.D. Yang, X.J. Wang, S.B. Chen // Проблемы прочности. — 2015. — № 1. — С. 187-193. — Бібліогр.: 8 назв. — англ. |
| collection | DSpace DC |
| container_title | Проблемы прочности |
| description | High-strength low-alloy steel 50 mm thick is well joined by metal-active gas double-sided doublepower arc welding, which does not require preheating, postheating, and back chipping. Mechanical properties of the weld seam and base metal were investigated. Results of the tensile test indicate that the strength of the weld seam is about 862.73 MPa and its average elongation is 20.74%. The hardness of the base metal and weld zone is 299 and 361 HV, respectively. The maximum hardness (395 HV) is observed in the heat-affected zone. The average toughness of the face and root sides of the weld center is 75 and 71 J, respectively.
Высокопрочная низколегированная сталь толщиной 50 мм хорошо соединяется с помощью двухсторонней дуговой сварки металлическим электродом в среде активного защитного газа при наличии двух источников питания, которая не требует предварительного и последующего нагрева, а также вырубки корня шва. Исследованы механические свойства сварного шва и основного металла. Результаты испытания на растяжение показывают, что прочность сварного шва составляет примерно 862,73 МПа, а среднее удлинение 20,74%. Твердость основного металла и зоны шва составляет соответственно 299 и 361 HV. Максимальная твердость (395 HV) наблюдается в зоне термического влияния. Средняя жесткость лицевой стороны и корня шва в центре составляет 75 и 71 Дж соответственно.
|
| first_indexed | 2025-12-01T13:34:52Z |
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UDC 539.4
Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded
Joints of High-Strength Low-Alloy Steel
Y. X. Chen,
a,b,1
C. D. Yang,
b
X. J. Wang,
c
and S. B. Chen
b
a School of Mechanical and Electrical Engineering, Hohai University, Changzhou, China
b Intelligentized Robotic Welding Technology Laboratory, School of Materials Science and Engineering,
Shanghai Jiao Tong University, Shanghai, China
c Jiangsu University of Science and Technology, Zhenjiang, China
1 cyx1978@yeah.net
High-strength low-alloy steel 50 mm thick is well joined by metal-active gas double-sided double-
power arc welding, which does not require preheating, postheating, and back chipping. Mechanical
properties of the weld seam and base metal were investigated. Results of the tensile test indicate that
the strength of the weld seam is about 862.73 MPa and its average elongation is 20.74%. The
hardness of the base metal and weld zone is 299 and 361 HV, respectively. The maximum hardness
(395 HV) is observed in the heat-affected zone. The average toughness of the face and root sides of
the weld center is 75 and 71 J, respectively.
Keywords: high-strength low-alloy steel, double-sided double arc welding, multilayer
welding, mechanical properties.
Introduction. High-strength low-alloy (HSLA) steel is a type of structural steel,
which is often used in ship hulls, pressure vessels, oil and gas pipelines, due to its excellent
mechanical properties, outstanding resistance to corrosion and good weldability. Up to now,
HSLA steel welding has been successfully provided by such welding techniques as arc
welding (AW), in particular, gas metal arc welding (GMAW), electron beam welding
(EBW), laser welding (LW), etc.
Currently, the AW procedure involves the following steps: preheating, GMAW at one
side, then back chipping by carbon arc air gouging, polishing, magnetic particle examination,
the repeated preheating, GMAW at the other side, final postheating, etc. This complex
procedure is characterized by a low productivity, requires a large-scale filler metal addition,
and produces large distortions due to the nonuniform welding shrinkage [1]. Fortunately,
EBW and LW processes, which involve deeper subsurface layers of the welded material,
can overcome the above disadvantage. However, both processes require a close tolerance
joint fit-up and imply high operation costs. Therefore, there is an urgent requirement for
developing advanced welding techniques with deep welding penetration to join HSLA steel
structures and components, especially those with a high thickness.
Recently, a new high-efficiency technique, which requires no back chipping, namely,
the double independent power double-sided double arc welding (DSDAW), becomes more
and more popular in the HSLA welding applications. In the welding process, the backing
pass/run is produced by the double-sided pulse gas tungsten arc welding (GTAW), while
other passes are made with the double-sided GMAW. The operation process is quite simple,
and the productivity is very high. However, the majority of studies on this welding
technique are focused on either thin or medium-thickness plate welding structures [2–4].
Thus, the thick-plate welding needs to be developed and verified, in order to widen the
applications of the newly emerged techniques. Meanwhile, more efforts are still required to
evaluate the effect of welding parameters on microstructure and mechanical properties of
thick-plate weld structures.
© Y. X. CHEN, C. D. YANG, X. J. WANG, S. B. CHEN, 2015
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1 187
In the present work, the microstructure and mechanical properties of a thick plate of
Q690 steel welded by the metal active gas (MAG) welding DSDAW process without
preheating, postheating and back chipping are investigated.
1. Experimental Procedures.
1.1. Material and Welding Procedure. The new DSDAW technology is a double,
independent power type DSDAW, which is different from a single-power one presented by
Zhang [4]. The basic principle of this new welding technique is illustrated by Fig. 1. The
backing pass is produced by the double-sided double pulse GMAW; two weld torches are
placed at the front and back sides of the plate and are individually supplied by weld power
1 and power 2.
Double-sided double MAG torches (see Fig. 1) ensure the required arc distance to
realize an asymmetric DSDAW in the back pass, while other passes are produced by the
double-sided double GMAW. Two MAG torches are symmetrically placed on both sides of
the plate and supplied by two independent weld powers individually. Here Y is the welding
direction, Z is the thickness direction, and X is the width direction, which is normal to the
welding direction.
In this study, welding experiments were carried out to investigate the new DSDAW
method, which requires no preheating, postheating, and back chipping and involves two
independent multipass welding arcs. The total weld process consists of 24 passes, e.i., 12
passes are made on the front and back sides of the plate. The base material is Q690 steel
with dimensions of 50�70�240 mm, a double-V symmetric groove with an opening
angle of 45�, and the root gap of 4 mm. The filler material is YM-80A alloy welding wire
with a diameter of 1.2 mm. The chemical composition of the base metal and electrode wire
is listed in Table 1. The shielding gas flow rate is 20 l per minute and welding speed is
240 mm per minute. The welding process is performed using gas metal arc according to the
standard welding parameters.
Y. X. Chen, C. D. Yang, X. J. Wang, and S. B. Chen
188 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1
Fig. 1. Scheme of the double-sided double MAG technique.
T a b l e 1
Chemical Composition of Base Metal and Filler Wire
Material Element
C Si Mn P S Ni Cr Mo
Q690 steel
Filler metal
0.10
0.07
0.23
0.34
0.54
0.74
0.009
–
0.007
–
4.10
1.23
0.53
–
0.36
–
The welded joints were cut out perpendicular to the welding direction and cold-
mounted, in order to examine the microstructure of the fusion zone, heat-affected zone
(HAZ), and base metal. The mounted specimens were manually ground, polished, and
etched using 5 vol.% HNO3–95 vol.% C2H5OH solution. The microstructure and fracture
morphology of specimens were analyzed by scanning electron microscope (SEM), while
their chemical composition was characterized by the energy disperse spectroscopy (EDS).
A universal testing machine was used for the experimental determination of the ultimate
tensile strength and elongation of the specimens.
2. Results and Discussion.
2.1. Hardness Variation. The Vickers hardness measurements of the weld metal were
performed in the HAZ, fusion line, and weld center, respectively. The respective specimens
were cut out from the face side (2 mm below the weld metal surface) and the root side
(25 mm below the weld metal surface) of the weld metal, as shown in Fig. 2a. At least
three specimens with a spacing of 0.5 mm were tested in each hardness test, and the
average values were plotted in Fig. 2b. Hardness values for the base metal and weld zone
are 299 and 361 HV, respectively. The maximum hardness value (395 HV) is observed on
the HAZ face side. These results can be exlpained via the analysis of the weld metal
microstructure.
The microstructure of low-alloy steels is quite complex, consisting of different
morphologies of ferrite (including allotriomorph ferrite, ferrite side plates, and acicular
ferrite), bainite, microphases and some inclusions. Microphase is a collective term for small
fractions of martensite, degenerated pearlite, and retained austenite that develops from
saturated austenite at the last stage of transformation.
Figure 3 shows a typical cross-sectional macrograph of the multipass welded joint,
which is composed of weld metal with coarse grain zone, overheated zone, and base metal.
During DSDAW, the arc heating and chilling thermal cycles are responsible for the
formation of acicular ferrite, granular bainite and martensitein weld metal as shown in
Fig. 3c. The hardness of martensite phase is higher than ferrite phase. Therefore, the weld
center has a higher hardness than HAZ.
Moreover, in all welded specimens, the maximum hardness occurs at the surface of
fusion line. This is attributed to higher cooling rates due to the chilling effect of the
adjacent base metal. During welding, high peak temperature thermal cycles are responsible
for austenite grain growth in the base plate near the weldment. The grain size decreases as
the peak temperature falls monotonically with distance from the fusion line. Therefore, the
coarse grain zone is located next to the fusion line, while the fine grain zone is located
marginally away from the fusion line. Meanwhile, the martensite phase growth decreases
Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints ...
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1 189
a b
Fig. 2. Hardness measurement positions (a) and hardness profile (b) of the weld metal.
with distance from the fusion line. As a result, various sections of the HAZ develop
different microstructures with different mechanical properties.
2.2. Tensile Strength. It is found that the average tensile strength of welded joint is
862.73 MPa, the average elongation 20.74%. Figure 4 show the fracture micromorphologies
of weld and fusion line by SEM, which explains the scatter between the tensile test results.
Compared with fusion line in surface fracture, the dimples of weld are deeper and
distributed more uniformly, indicating a higher toughness. Moreover, more second-phase
particles are dispersed in the dimples at the fracture surface of the fusion line, which
phenomenon implies a higher hardness. However, the improved mechanical properties of
190 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1
a b
c d
Fig. 3. Microstructure of DSDAW weld metal: (a) base metal; (b) overheated zone; (c) weld metal;
(d) coarse grain zone.
a b
Fig. 4 Fracture morphologies of weld (a) and fusion line (b).
Y. X. Chen, C. D. Yang, X. J. Wang, and S. B. Chen
weld are attributed to the finer grain size. In the process of DSDAW, the second heat cycle
is induced by the rear pass, which can be treated as a post-heating action to the fore pass.
Similarly, the fore pass provides a preheating for the rear pass and, consequently, the
resulting grain size can be reduced.
2.3. Charpy Impact Toughness. The impact test results for each specimen and thier
average values, which are listed in Table 2, indicate that the Charpy impact toughness
values correlate well with hardness and tensile properties. A general increase in the Charpy
impact toughness with the distance from the weld fusion line is observed. The toughness of
the weld face is higher than that of the weld root. There are several parameters affecting the
impact toughness of the weld joints:
(i) hardness (or strength) level;
(ii) microstructure (share of different regions in the Charpy notch zone);
(iii) characteristics of inclusions like volume fraction, size, and spacing [5].
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1 191
T a b l e 2
All-Weld Metal Charpy Absorbed Energy
Notch location Discrete values (J) Average value (J)
Weld center (face/root) 76, 78, 72/66, 74, 72 75/71
Fusion line (face/root) 76, 76, 60/62, 68, 60 71/63
Fusion line + 2 mm (face/root) 162, 178, 152/162, 152, 150 164/155
Fusion line + 5 mm (face/root) 160, 162, 166/92, 160, 156 163/136
a
b
Fig. 5. Microstructure (a) and EDS results (b) for the root side in the weld center.
Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints ...
In generally, the toughness value decreases with hardness (or strength), because the
material susceptibility to plastic deformation reduces, and hence work of fracture decreases.
Some microstructural constituents, like an acicular ferrite, have higher strength and
hardness than other ferrite morphologies, but also are characterized by a high level of the
impact toughness [5–7]. Microstructures like bainite, which includes parallel bands with
low-angle boundaries, also have a low impact toughness.
However, one of the measured Charpy impact toughness values, which corresponds to
th weld foot in the weld center, is 66 J, which is less than other values (74 and 72 J,
respectively), as is shown in Table 2. To clarify this problem, a comprehensive analysis of
the fusion and solidification processes of the Q690 workpiece during multipass welding is
required. Figure 5a illustrates the microstructure of the root side in the welding center,
while the EDS analysis results presented in Fig. 5b indicate that the inclusion particle is
mainly composed of O, Mn, Si, and Fe elements. In multipass welds, the shielding gas or
the addition of CO2 or O2 to argon interacts with the weld pool and causes oxidation, which
results in some loss of alloy constituents and produces inclusions in the weld. Especially,
inclusions like welding slag SiO2 should be considered in the multipass welds. Presence of
a very high volume fraction of inclusions may initiate a premature ductile fracture [8]. In
general, the presence of inclusions is detrimental to weld properties.
C o n c l u s i o n s
1. Q690 HSLA steel of 50 mm in thickness is effectively joined by DSDAW process
without preheating, postheating and back chipping.
2. The average tensile strength of DSDAW is 862.73 MPa, and the average elongation
is 20.74%. Compared with fusion line, the dimples on the fracture surface of weld are
deeper and more uniformly distributed, which indicates a higher toughness.
3. Hardness in the base metal and weld zone is 299 and 361 HV, respectively. The
maximum value of hardness (395 HV) occurs in the HAZ. Furthermore, the higher strength
of weld metal is as a result of faster cooling rate which leads to formation of a higher share
of martensite.
4. The average toughness values of the face and root sides of the fusion line are 71
and 63 J, respectively. The average toughness values of the face and root sides of the weld
center are 75 and 71 J, respectively. The impact properties of weld metals improve with the
share of acicular ferrite in as-deposited regions. Nevertheless, the toughness reduction may
be due to inclusions like the remaining slag in the multipass weld.
Acknowledgments. The authors would like to express their gratitude to Shanghai Jiao
Tong University for the financial support of this study through Grant No. 201310211468.
Also, this work was supported by Changzhou Natural Science Foundation Project No.
CJ20130031.
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double-sided welding and double-sided arc welding of 6 mm 5A06 aluminium alloy,”
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709–713 (2013).
192 ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1
Y. X. Chen, C. D. Yang, X. J. Wang, and S. B. Chen
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Received 20. 10. 2014
ISSN 0556-171X. Ïðîáëåìû ïðî÷íîñòè, 2015, ¹ 1 193
Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints ...
|
| id | nasplib_isofts_kiev_ua-123456789-173280 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0556-171X |
| language | English |
| last_indexed | 2025-12-01T13:34:52Z |
| publishDate | 2015 |
| publisher | Інститут проблем міцності ім. Г.С. Писаренко НАН України |
| record_format | dspace |
| spelling | Chen, Y.X. Yang, C.D. Wang, X.J. Chen, S.B. 2020-11-28T15:40:50Z 2020-11-28T15:40:50Z 2015 Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel / Y.X. Chen, C.D. Yang, X.J. Wang, S.B. Chen // Проблемы прочности. — 2015. — № 1. — С. 187-193. — Бібліогр.: 8 назв. — англ. 0556-171X https://nasplib.isofts.kiev.ua/handle/123456789/173280 539.4 High-strength low-alloy steel 50 mm thick is well joined by metal-active gas double-sided doublepower arc welding, which does not require preheating, postheating, and back chipping. Mechanical properties of the weld seam and base metal were investigated. Results of the tensile test indicate that the strength of the weld seam is about 862.73 MPa and its average elongation is 20.74%. The hardness of the base metal and weld zone is 299 and 361 HV, respectively. The maximum hardness (395 HV) is observed in the heat-affected zone. The average toughness of the face and root sides of the weld center is 75 and 71 J, respectively. Высокопрочная низколегированная сталь толщиной 50 мм хорошо соединяется с помощью двухсторонней дуговой сварки металлическим электродом в среде активного защитного газа при наличии двух источников питания, которая не требует предварительного и последующего нагрева, а также вырубки корня шва. Исследованы механические свойства сварного шва и основного металла. Результаты испытания на растяжение показывают, что прочность сварного шва составляет примерно 862,73 МПа, а среднее удлинение 20,74%. Твердость основного металла и зоны шва составляет соответственно 299 и 361 HV. Максимальная твердость (395 HV) наблюдается в зоне термического влияния. Средняя жесткость лицевой стороны и корня шва в центре составляет 75 и 71 Дж соответственно. The authors would like to express their gratitude to Shanghai Jiao Tong University for the financial support of this study through Grant No. 201310211468. Also, this work was supported by Changzhou Natural Science Foundation Project No. CJ20130031. en Інститут проблем міцності ім. Г.С. Писаренко НАН України Проблемы прочности Научно-технический раздел Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel Оценка качества швов, полученных двухсторонней дуговой сваркой с двумя источниками питания, на высокопрочной низколегированной стали Article published earlier |
| spellingShingle | Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel Chen, Y.X. Yang, C.D. Wang, X.J. Chen, S.B. Научно-технический раздел |
| title | Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel |
| title_alt | Оценка качества швов, полученных двухсторонней дуговой сваркой с двумя источниками питания, на высокопрочной низколегированной стали |
| title_full | Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel |
| title_fullStr | Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel |
| title_full_unstemmed | Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel |
| title_short | Evaluation of Metal-Active Gas Double-Sided Double-Power Arc Welded Joints of High-Strength Low-Alloy Steel |
| title_sort | evaluation of metal-active gas double-sided double-power arc welded joints of high-strength low-alloy steel |
| topic | Научно-технический раздел |
| topic_facet | Научно-технический раздел |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/173280 |
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