Materials Sciences and Applicatio ns, 2011, 2, 1443-1451
doi:10.4236/msa.2011.210195 Published Online October 2011 (http://www.SciRP.org/journal/msa)
1443
Effect of Laser Beam Welding Parameters on
Microstructure and Properties of Duplex
Stainless Steel
Abdel-Monem El-Batahgy1, Abdel-Fattah Khourshid2, Thoria Sharef2
1Manufacturing Technology Department, Central Metallurgical Research and Development Institute, Cairo, Egypt; 2Mechanical De-
sign and Production Department, Faculty of Engineering, Tanta University, Tanta, Egypt.
Received June 26th, 2011; revised July 19th, 2011; accepted August 25th, 2011.
ABSTRACT
The present study is concerned with laser beam welding and its effect on size and microstructure of fusion zone then, on
mechanical and corrosion properties of duplex stainless steel welded joints. In this regard, influence of different laser
welding parameters was clarified. Both bead-on-plate and autogenously butt welded joints were made using carbon
dioxide laser with a maximum output of 9 kW in the continuous wave mode. Welded joints were subjected to visual, dye
penetrant and radiography tests before sectioning it for different destructive tests. Accelerated corrosion test was car-
ried out based on tafel plot technique. The results achieved in this investigation disclosed that welding parameters play
an important role in obtaining satisfactory properties of welded joint. High laser power and/or high welding speed to-
gether with adjusting laser focused spot at specimen surface have produced welded joints with a remarkable decrease
in fusion zone size and an acceptable weld profile with higher weld depth/width ratio. Besides, acceptable mechanical
and corrosion properties were obtained. Using nitrogen as a shielding gas has resulted in improving mechanical and
corrosion properties of welded joints in comparison with argon shielding. This is related to maintaining proper fer-
rite/austenite balance in both weld metal and HAZ in case of nitrogen shielding. As a conclusion, laser power, welding
speed, defocusing distance and type of shielding gas combination have to be optimized for obtaining welded joints with
acceptable profile as well as mechanical and corrosion properties.
Keywords: Duplex Stainless Steel, Laser Beam Welding, Laser Power, Welding Speed, Defocusing Distance, Shielding
Gas Type, Fusion Zone, Microstructure, Mechanical Properties, Corrosion Resistance
1. Introduction
The duplex stainless steels have been developed to pro-
vide a combination of strength and resistance to pitting
and stress corrosion cracking in comparison with the
300-series austenitic stainless steels [1-3]. These unique
properties of the duplex stainless steels have resulted in
their use in a variety of industrial applications, including
chemical process plant piping, oil and gas transmission
lines, and structures for use in marine environments [4,5].
Since welding is widely used in these applications, un-
derstanding the factors which affect the weldability of
duplex stainless steels is critical to the successful imple-
mentation of these engineering materials.
Generally, the ferrite/austenite balance has a remark-
able influence on both mechanical and corrosion proper-
ties of duplex stainless steels [6,7]. The optimum proper-
ties of duplex stainless steels are achieved when nearly
equal proportions of austenite and ferrite are present in
the microstructure. In base metals, this phase balance is
obtained by an appropriate combination of composition
and solution heat treatment. However, control of the fer-
rite/austenite balance in welds is not as straightforward
as in the base metals [8-11].
Previous investigations have demonstrated that micro-
structure of both weld and heat affected zones is a func-
tion of the cooling rate from peak temperature [12-15].
Consequently, it is expected that the ferrite/austenite
balance in fusion zone is affected by laser power and
welding speed. However, this research area has received
comparatively little investigations and more work is re-
quired for deep understanding the effect of different laser

Effect of Laser Beam Welding Parameters on Microstructure and Properties of Duplex Stainless Steel 1444
welding parameters on properties of duplex stainless
steels. The present study is concerned with laser beam
welding and its effect on size and microstructure of fu-
sion zone then, on mechanical and corrosion properties
of duplex stainless steel welded joints.
2. Experimental Procedure
The used steel is a commercial duplex stainless steel;
2205 with 6.4 mm plate thickness. Its chemical composi-
tion and mechanical properties are given in Table 1.
Both bead-on-plate and autogenously single pass square
butt welds were made using CO2 laser beam welding
process. Schematic illustration of laser butt welding joint
is shown in Figure 1. Weld specimens (150 × 100 × 6.4
mm) were prepared as square butt joints with machined
surfaces and were held firmly using fixture to prevent
distortion. Laser beam welding parameters studied are
given in Table 2.
The used laser was a carbon dioxide with a maximum
output power of 9 kW in the continuous wave mode. Af-
ter welding, the specimens were visually inspected, ra-
diographed then, sectioned transverse to the welding di-
rection where it were subjected to metallographic ex-
aminations as well as mechanical and corrosion tests. For
metallographic examination, the specimens were pre-
pared using standard techniques. The size and micro-
structure of fusion zone were examined using optical
microscope. Compositional variations across welded
joints were determined in scanning electron microscope
equipped with an energy dispersive spectrometer (EDS)
at an accelerating voltage of 30 kV. The elements ana-
lyzed included both ferrite and austenite stabilizing ele-
ments.
Mechanical tests including tensile, bending and hard-
ness were performed for laser beam butt welded joints
having complete penetration. These tests were performed
at room temperature according to relevant standards.
Tensile test was performed for three samples in each
condition and the data reported are the average of the
three individual results. The given hardness values are
the average of five readings. Regarding corrosion test,
selected laser beam welded samples were subjected to
accelerated corrosion test based on tafel plot technique
where corrosion rate was measured using Potentio-
stat—Auto Lab PGSTAT 30 device.
3. Results and Discussion
3.1. Effect of Laser Power
The effect of laser power was clarified using 0.5m/min
welding speed, 0.0 and −2.0 mm defocusing distances.
Figure 2 shows macrographs of cross sections of laser
bead-on-plate welds made using 0.5 m/min welding
Figure 1. Schematic illustration of laser butt welding joint.
Table 1. Chemical composition (wt%) and mechanical properties of used base metal.
Chemical composition
Cr Ni Mn C Si P S Mo Cu N
21.9 4.70 1.71 0.03 0.50 0.03 0.002 2.60 0.20 0.17
Mechanical properties
Tensile strength (MPa) Yield strength (MPa) Elongation (%)
730 685 30
Table 2. Laser beam welding parameters.
Weld type P (kW) S (m/min) △Z (mm) Shielding gas/ Flow rate (l/min)
Bead-on-plate 4, 5, 6, 7, 7.5, 8 0.5 −2, 0 Argon/20
Bead-on-plate 7 0.25, 0.4, 0.5, 1, 2, 3, 4, 5, 6 −2, 0 Argon/20
Bead-on-plate 7 0.5 3, 2, 1, 0, −1, −2, −3, −4 Argon/20
Butt joint 8 0.25, 0.5 −2 Nitrogen/20
P: Power; S: Speed; △Z: Defocusing distance.

Effect of Laser Beam Welding Parameters on Microstructure and Properties of Duplex Stainless Steel1445
Figure 2. Macrographs of cross sections of laser bead-on-plate welds made using 0.5 m/min speed, −2 mm defocusing dis-
tance, 20 l/min Ar and different laser powers. (a) 4 kW; (b) 5 kW; (c) 7 kW; (d) 8 kW.
speed, −2 mm defocusing distance, 20 l/min Ar and dif-
ferent laser powers. It is clear that penetration depth in-
creases with increasing laser power. The weld bead
showed a characteristic of laser welding where the de-
velopment of the weld is essentially symmetrical about
the axis of the laser beam. No welding cracks or porosity
were found and this could be partly due to the good crack
resistance of the base metal and the welding conditions
provided. Figure 3 summarizes the results of penetration
depth measurements as a function of laser power. It can
be noticed that penetration depth is sharply increasing
with the increase of laser power. It increased from
3.4mm to 4.7mm with increasing power from 4 to 8 kW.
3.2. Effect of Laser Welding Speed
Macrographs of cross sections of laser bead-on-plate
welds made using 8 kW laser power, –2 mm defocusing
distance, 20 l/min Ar and different welding speeds are
shown in Figure 4. It is noteworthy that the fusion zone
is symmetrical about the axis of the laser beam. However,
size and depth/width ratio of fusion zone are significantly
affected by welding speed. A lower welding speed re-
sulted in a remarkable increase in the fusion zone size.
Also, weld depth/width ratio was remarkably increased
with decreasing welding speed. Consequently, acceptable
weld profile was obtained where the fusion zone inter-
face is a smooth curve with no inflections. Complete
penetration with relatively acceptable fusion zone size
for the 6.4 mm base metal thickness was obtained at
welding speed of 0.25 m/min (Figure 4(d)). In other
words, 0.25 m/min is considered as the optimum welding
speed at 8kW laser power since it resulted in fusion zone
with a slight taper configuration. This fusion zone shows
a characteristic of laser welding with an acceptable weld
depth/width ratio. At low welding speed, attenuation of
beam energy by plasma is less significant. This results in
relatively more exposure of the laser beam on the sample
surface. Consequently, the depth/width ratio would be
decreased and the fusion zone would be increased.
Inspite of the development of the weld is essentially
symmetrical about the axis of the laser beam, increase
0.5m/min, -2.0mm, 20l/min Ar
2
2.5
3
3.5
4
4.5
5
345678
Power, k W
Dep th , mm
9
Figure 3. Effect of laser power on weld depth of laser bead-
on-plate welds made using 0.5 m/min speed and −2 mm
defocusing distance and 20 l/min Ar shielding.
penetration at the root side was observed particularly at
lower welding speed suggesting an unsteady fluid flow.
This is due to the presence of two strong and opposing
forces, namely, the electromagnetic and the surface ten-
sion gradient forces. At these locations, the electromag-
netic force may have overcome the surface tension force,
thereby, influencing convective heat transfer. As a result,
any local perturbation in the over weld can cause the
flow field to change dramatically, resulting in the ob-
served increased penetration.
It can be noticed that no welding cracks or porosity
were found and this could be partly due to the good crack
resistance of base metal and the welding conditions pro-
vided. Figure 5 summarizes the results of weld depth
measurements as a function of welding speed. Weld
depth is decreased with the increase in welding speed. It
decreased from 7.4mm to 1.9mm with increasing weld-
ing speed from 0.25 to 6 m/min.
3.3. Effect of Defocusing Distance
Defocusing distance, focus position, is the distance be-
tween specimen surface and optical focal point. In order
to study its effect on both penetration depth and weld
profile, bead-on-plate was made with changing defocus-
ing distance of −4.0 mm up to 3.0 mm. Welding condi-
tions were selected to obtain incomplete penetration.
2mm
(a) 2mm (b) 2mm (c) 2mm (d)

Effect of Laser Beam Welding Parameters on Microstructure and Properties of Duplex Stainless Steel 1446
Figure 4. Macrographs of cross sections of laser bead-on-plate welds made using 8 kW laser power, –2 mm defocusing dis-
tance, 20 l/min Ar and different welding speeds. (a) 5 m/min; (b) 1 m/min; (c) 0.5 m/min; (d) 0.25 m/min.
8kW, 0.0mm, 20l/min Ar
0
2
4
6
8
10
01234567
Speed, m / mi n
Depth, mm
Figure 5. Effect of welding speed on weld depth of laser
bead-on-plate welds made using 8 kW power, −2 mm defo-
cusing distance and 20 l/min Ar shielding.
Examples of macrographs of cross sections of laser
bead-on-plate welds made using 8 kW power, 0.5 m/min
welding speed, 20 l/min argon shielding and different
defocusing distances are shown in Figure 6. No cracking
or porosity was observed in all welds. Figure 7 summa-
rizes results of weld bead depth/width ratio as a function
of defocused distance of laser bead-on-plate welds made
using 8 kW power, 0.5 m/min welding speed and 20 l/min
Ar. Changing defocusing distance from zero to either
minus or plus values has resulted in decrease in depth/
width ratio. In other words, shifting the focused beam
position to either below or above specimen surface re-
sults in decrease in depth/width ratio. However, shifting
the focused beam position above the specimen surface
results in much decrease in depth/width ratio in com-
parison with shifting it below specimen surface. This is
related to decrease in laser beam density in case of shift-
ing the focused beam position above specimen surface.
The above results are in good agreement with other re-
search work [16].
3.4. Effect of Type of Shielding Gas
Based on results obtained from above experiments, op-
timum welding parameters were obtained and imple-
mented for welding square butt joints. Nondestructive
investigations including visual, dye penetrant and radio-
graphic tests confirmed that laser butt welded joint is free
from both external and internal defects. Then, welded
joint was sectioned for metallographic examinations.
Figure 8(a) shows macrograph of a cross section of laser
butt welded joints made using 8 kW power, 0.5 m/min
speed, 0.0mm defocusing distance and 20 l/min argon.
Fusion zone shows a characteristic of laser welding with
complete penetration and acceptable weld profile where
the fusion zone interface is a smooth curve with no in-
flections.
In order to clarify the effect of shielding gas type, ar-
gon was replaced by nitrogen with other welding condi-
tions kept constant. Figure 8(b) shows macrograph of a
cross section of laser butt welded joint made using 8 kW
power, 0.5 m/min speed, 0.0 mm defocusing distance and
20 l/min nitrogen. It can be noticed that typical laser
weld with complete penetration and acceptable weld pro-
file, similar to that of argon shielding, was obtained.
3.5. Microstructure of Laser Butt Welds
The microstructure of the used 2205 duplex stainless
steel base metal is shown in Figure 9. It can be noticed
that this microstructure is duplex with approximately
equal volumes of both ferrite and austenite phases. Since
hot working of duplex stainless steel is normally per-
formed in the austenite-ferrite, two phase region, the re-
sultant microstructure tends to be strongly oriented along
the working direction. An average hardness value of
about 305 Hv was obtained for this microstructure.
Optical micrographs of laser butt welded joint made
using 8 kW power, 0.5 m/min speed, 0.0 mm defocusing
distance and 20 l/min of argon and nitrogen shielding are
shown in Figures 10 and 11 respectively. The noticeable
feature is the highly directional nature of the microstruc-
ture around the axis of the laser beam in both cases. This
is due to solidification of the weld metal at high cooling
rate. No solidification cracking was found in the weld
structure. Structures of weld metal in both joints were
almost similar. For weld metal, a dendritic microstructure
was developed at fusion boundary due to fast cooling
conditions (Figures 10(c), 11(c)). More globular struc-
tures were observed at weld metal center that exposed to
2mm
(a) 2mm (b) 2mm
(c) 2mm
(d)

Effect of Laser Beam Welding Parameters on Microstructure and Properties of Duplex Stainless Steel1447
Figure 6. Macrographs of cross sections of laser bead-on-plate welds made using 8 kW power, 0.5 m/min speed, 20 l/min Ar
with difference defocusing distances. (a) Dd = −4 mm; (b) Dd = −1 mm; (c) Dd = 0.0 mm; (d) Dd = +3 mm.
Depth/ W idth Rat io
0
0.2
0.4
0.6
0.8
1
1.2
-6-4-2024
Defocusi ng Di st ance , m m
Figure 7. Weld bead depth/width ratio versus defocusing
distance of laser bead-on-plate welds made using 8 kW
power, 0.5 m/min speed and 20 l/min Ar.
(a) 3mm
(
b
)
3mm
Figure 8. Macrographs of cross sections of laser butt welded
joints made using 8 kW power, 0.5 m/min speed, 0.0 mm
defocusing distance and 20 l/min of (a) argon; (b) nitrogen.
lower cooling rates and with a less pronounced heat flow
direction. During solidification of duplex weld metal an
almost completely ferrite structure is formed. Further
cooling initiates the formation of the austenite phase nu-
cleating at the ferrite grain boundaries. In other words,
duplex stainless steel weld metal solidifies completely to
α-ferrite and the volume fraction of austenite is deter-
mined by subsequent solid state phase transformation
(17).
50
µ
m
Figure 9. Optical micrographs of base metal of duplex stain-
less steel used.
Regarding heat affected zone, its microstructure is
critical for welded joint properties. In general, narrow
HAZ of about 400 - 500 µm was observed for the exam-
ined welds (Figures 10(a), 11(a)). The heat affected
zone is consisting firstly of a grain growth zone charac-
terized by coarse α-ferrite grains decorated with al-
lotriomorphic layers of austenite, some austenite plates
and some intra-granularly nucleated particles formed on
inclusions where the volume fraction of austenite in this
region is low compared with the base metal. Beyond this
partially ferritised zone, the major difference being the
spacing of the grains which is a function of the distance
from the fusion zone and the peak temperature reached
during heating. In other words, the coarse grained region
adjacent to the fusion line could be resulted from nearly
complete austenite dissolution on heating and subsequent
ferrite grain growth. Higher magnifications for HAZ mi-
crostructure are shown in color etching in Figure 12 and
hardness measurements allowed a clear distinction be-
tween the ferrite and austenite in both weld metal and
HAZ. The ferrite content in both weld metal and HAZ
was relatively higher in comparison to base metal. This
has been confirmed using energy dispersive X-ray (EDX)
technique. Results showed that the concentrations of
elements; such as Cr and Mn in ferrite phase is higher,
while Ni concentration is lower than in austenitic phase.
The element partitioning between ferritic and austenitic
phase is consistent with the stabilizing effect of each
2mm
(a) 2mm
(b) 2mm
(c) 2mm
(d)

Effect of Laser Beam Welding Parameters on Microstructure and Properties of Duplex Stainless Steel 1448
Figure 10. Optical micrographs of laser butt welded joint made using 8 kW power, 0.5 m/min speed, 0.0 mm defocusing dis-
tance and 20 l/min argon shielding.
Figure 11. Optical micrographs of laser butt welded joint made using 8 kW power, 0.5 m/min speed, 0.0 mm defocusing dis-
tance and 20 l/min nitrogen shielding.
(a)
HAZ
100
µ
m
WM
(b)
HAZ
100
µ
m
WM
Figure 12. Color etched optical micrographs of HAZ of
laser butt welded joint made using 8 kW power, 0.5 m/min
speed, 0.0 mm defocusing distance and 20 l/min of (a) argon
shielding; (b) nitrogen shielding.
element on the respective phase.
Generally, laser weld results in a rapid cooling rate
through the transformation temperature range which in
turn resulted in decreasing austenite content and this
agreed qualitatively with optical metallography. Variation
in ferrite/austenite balance among different heat input of
laser welds can be rationalized using a constant iron sec-
tion of a Fe-Cr-Ni ternary phase diagram. The composition
band superimposed on the 60% constant iron section is
representative of the range of duplex stainless steel con-
sidered in this investigation. The diagram predicts that
primary solidification of this alloy occurs as delta ferrite
and that the structure is completely ferritic at completion
of solidification. On cooling in the solid state, partial trans-
formation of ferrite to austenite occurs at temperatures
below the ferrite solves. The austenite content formed
during cooling in solid state is depended on cooling rate.
The higher the laser power and/or the lower welding speed,
the coarser is the dendritic structure due to decreasing
cooling rate. However, the effect of laser power was rela-
tively less than that of welding speed.
3.6. Mechanical Properties of Laser Butt Welds
Hardness profile through weld metal, HAZ and base
metal of welded joint made using 8 kW power, 0.5
m/min speed, 0.0 mm defocusing distance and 20 l/min
argon is shown in Figure 13. It can be noticed that no
significant difference in hardness values of weld metal,
HAZ and base metal was obtained. Similar hardness pro-
file was obtained in case of nitrogen shielding.
The bending test at room temperature showed good
ductility for all joints where no cracks were found after
U-bends made. Results of tensile test of laser butt welded
joint, made using 8 kW power, 0.5 m/min speed, 0.0 mm
(a)
HAZ
400
µ
m
BM
WM
(b)
HAZ
100
µ
m
BM
(c) 50
µ
m
WM
(a)
HAZ
400
µ
m
BM
WM
(b)
HAZ
100
µ
m
BM
(c) 50
µ
m
WM

Effect of Laser Beam Welding Parameters on Microstructure and Properties of Duplex Stainless Steel1449
200
250
300
350
012345
Distance from Weld Centerline, mm
Hardness, HV (200g)
WM BMHAZ
Figure 13. Hardness profile through weld metal, HAZ and
base metal of welded joint made using 8 kW power, 0.5
m/min speed, 0.0 mm defocusing distance and 20 l/min ar-
gon.
defocusing distance and 20 l/min argon, as well as that of
base metal are shown in Table 3. Tensile tested welded
specimens were failed outside weld zone. Tensile proper-
ties of welded specimens are very close to that of base
metal. Only, ductility or elongation of welded joint is
slightly lower than that of base metal. This is related to
decreasing austenite volume fraction of welded joint in
comparison with base metal.
The obtained mechanical properties, in general, are
correlated to microstructure that was affected by shield-
ing gas type. In other words, mechanical properties of
welds made using nitrogen shielding are relatively im-
proved in comparison with that of welds made using ar-
gon shielding. This could be related to better balancing
of ferrite-austenite phases in both weld metal and heat
affected zone since nitrogen is austenite stabilizer and is
of great importance in the reforming of austenite that in
turn could result in structure with approximately equal
amounts of ferrite and austenite, similar to that of base
metal. This is conformed to results of other researchers’
work [18].
It should be reported that tensile elongation of laser
welded joint was not remarkably affected by increasing
heat input as a function of higher laser power and/or
lower welding speed inspite of higher austenite volume
fraction in this case. This could be related to larger fusion
zone size in case of higher heat input. In other words, the
effect of fusion zone size to decrease tensile elongation is
higher than the effect of austenite volume fraction to in-
crease it.
Table 3. Tensile properties of laser butt welded joint made
using 8 kW power, 0.5 m/min speed, 0.0 mm defocusing
distance and 20 l/min argon, as well as that of base metal.
Tensile
specimen
Tensile strength
(MPa)
Yield strength
(MPa)
Elongation
(%)
Welded joint713 669 25
Base metal 730 685 30
3.7. Corrosion Properties of Laser Butt Welds
The effect of both heat input, as a function of welding
speed, and shielding gas type on corrosion resistance of
laser butt welded joints are shown in Table 4 and Figure
14. It is found that corrosion rate of welded joint de-
creases with the increase in welding speed that means
with the decrease in heat input. This effect of heat input
can be rationalized in terms of cooling rate. For the low
heat input of laser welds, the fast cooling rate resulted in
insufficient amount of austenite and significant chro-
mium nitride precipitation. This could lead to depletion
of chromium around these precipitates which in turn
could have a deleterious effect on the pitting resistance.
It is found also that using nitrogen as a shielding gas to
replace argon, under same flow condition, has resulted in
a remarkable decrease in corrosion rate of welded joint
(Figure 14). Again, improvement in corrosion properties
of laser beam welded joints made using nitrogen as a
shielding gas is related to improvement in ferrite-auste-
nite balance in both weld metal and heat affected zone, as
has been reported by other research works [19,20].
4. Conclusions
Based on the results achieved in this study, it can be con-
cluded that laser power, welding speed, defocusing dis-
tance and type of shielding gas combinations have to be
optimized for obtaining welded joints with acceptable
fusion zone size, weld profile as well as mechanical and
corrosion properties.
The minimum fusion zone produced by laser beam is
depended on heat input as a function of laser power and
welding speed. High laser power and high welding speed
together with adjusting laser focused spot at specimen
surface have produced welded joint with a remarkable
decrease in fusion zone size and an acceptable weld profile
Table 4. Corrosion rate of laser beam welded joints made using different welding speeds and different shielding gases.
Welding condition Corrosion rate, mm/year Remarks
8 kW, 0.5 m/min, 20 l/min, Nitrogen 0.001637 Weld metal-fusion line corrosion
8 kW, 0.5 m/min, 20 l/min Argon 0.05334 Weld metal-fusion line corrosion
8 kW, 0.25 m/min, 20 l/min, Argon 0.2171 Weld metal-fusion line corrosion

Effect of Laser Beam Welding Parameters on Microstructure and Properties of Duplex Stainless Steel 1450
Figure 14. Comparison between corrosion rate of laser beam welded joints made using different welding speeds and shielding
gases.
with higher weld depth/width ratio. The nature of ferrite to
austenite transformation in fusion zone is strongly influ-
enced by cooling rate, which is depended on heat input as
a function of laser power and/or welding speed. Low heat
input laser welds resulted in considerable variation in the
ferrite/austenite balance of fusion zone relative to the base
metal as a result of high cooling rate.
Satisfactory mechanical properties including yield
strength, tensile strength, elongation and bending were
obtained for laser welds. Results indicated that heat input
has no remarkable effect on mechanical properties, ex-
cept elongation that was improved with either increasing
laser power or decreasing welding speed that means with
increasing heat input. This is related to maintaining pro-
per ferrite-austenite balance in fusion zone in this case.
Using nitrogen to replace argon as a shielding gas, under
same flow rate, has resulted in remarkable decrease in
corrosion rate and increase in ductility of welded joint.
Improvement in both mechanical and corrosion proper-
ties of laser beam welded joints made using nitrogen as a
shielding gas is related to maintaining proper ferrite-
austenite balance in both weld metal and heat affected
zone.
5. Acknowledgements
The authors would like to acknowledge Libyan Research
Institute for conducting laser beam welding experiments.
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