Key words : CO, laser beam welding, mild steel plate, absorption efficiency, water calorimetric ..... welding. The general layout of the CO2 laser machine and the.
[Quarterly Journal of Japan Welding Society, Vol. 17, No. 4, pp. 493-500 (1999)]
Measurement
of Beam Energy
by Tomohiko
SHIDA,
Taisuke
Absorption
WAKASA,
Susumu
in CO, Laser Beam Welding (2nd Report)
TSUKAMOTO
and
Kazuo
HIRAOKA
Abstract
Water-calorimetric measurements of absorption efficiencies in CO, laser beam welding of mild steel plates were made. In this study, the same measurement method was used to measure absorption efficiencies of heat in TIG-DCEN arc welding, electron beam welding in a high vacuum and CO2 laser beam welding. Improvements were applied to the welding jig and the measurement system used in the previous report No. 1. The absorption efficiencies for TIG arc welding and EB welding agreed with reported values in the literature. The values of absorption efficiency for CO, laser beam welding of mild steel specimen in bead-on-plate welding are changeable with welding conditions but generally in the range of 72-87%. Key words : CO, laser beam welding, mild steel plate, absorption efficiency, water calorimetric measurement
authors 1.
used the same measuring
considerable
Introduction
described Industrial various
applications
fields
spreading. applied
of
Metal in
is required
reason
Nd-YAG
as a welding
In the present absorption
mild
steel plates
ing
would
the
known,
or CO, laser
beams
are
a certain
amount
has been
study
measured
of
industrial
(Shida) subject.
widely
tried
efficiencies of heat in TIG arc welding and
using the same measuring
the accuracy 2.
selected
to measure
in CO, laser beam
in the belief
that
to better
improvements
method
to verify
of our measurements.
Measuring
method
of absorption
efficiency
using
the results
the
of
One of the co-authors also published to this report,
2.1
Measuring
system
using
water-calorimetry
of present
understanding of
the
welding
of weld-
processes
and
applications.
and Terauchi According
method)
efficiency again.
For this
There have been several reports on the topic published in the past.
the absorption
calorimetry
the authors
contribute
(water-calorimetric
is
Absorption
surface
applications.
method
electron beam (EB) welding in a high vacuum were also
beam
and
but made
in
steadily
laser
welding
in the welding
efficiency
phenomena,
wider
laser
in the report
principle
to the measuring
and measured
heat source.
heat
study
by
drilling,
As it is well
energy
power
fabrication
fabrication
cutting,
modification.
of high
material
improvements
of this report a report on this the absorption
The general
layout of the measuring
system is illus-
trated in Fig. 1. The measuring principle is the same as the previous system5~, but several important improvements are added to the previous the tank 1 is pumped
one. Cooling water
out by a constant
into the cooling channel of the welding jig. head in the tank is kept constant
in
volume pump The water
all the time. The outlet
efficiency of the CO, laser beam during bead-on-plate
water from the welding jig passes through
welding of a mild steel plate was in the range of 30-50%.
for reference.
However
is decided by dividing the exact mass of the total cooling
there were several problems
remaining
in this
report : namely accuracy of the laser power settings, the
water
method
the heat of welding from the backside
of applying
He side-shielding
gas and plume
control during welding, and the time constant speed)
of the sheathed
*Received
thermocouples.
(response
The present
by measuring
welding specimen.
: 1998 . 11. 19
of Ibaraki Institute
University for Metals
, Presently
time.
The cooling water
Each temperature
absorbs
of the T-shaped of the inlet water
to or the outlet water from the welding jig is separately
**Member
, Ibaraki University ***Formerly Graduate Student ****Member , National Research
a flow meter
The exact flow rate of the cooling water
Mitsutoyo
Corp.
研究論文
494
Tomohiko
SHIDA
et al.:
Measurement
of Beam Energy Absorption
Fig.3
Fig.1
General system.
layout
of the water-calorimetric
measured
Appearance
type temperature
The output signals from the thermistors computer
and necessary
are connected calculations
The appearthe welding
assembled
welding
jig and
Fig.5
Position
maximum
60°C. The electrical
acrylic
water temperature
by considering
thermal
and
The dimension of the jig is shown in Fig.
3 and the cross-section
at the mid-length is shown in Fig.
4. Acrylic pieces marked the cross-sectional Bead-on-plate
as A and B are used to adjust
area for cooling water flow. welding
through the slit opening.
in the flat position
sensor
is made
The water inlet and the outlet
holes of the jig are 10 mm in diameter thermistor
insulation
is placed,
respectively.
of the thermistor
temperature
specimen is shown in Fig. 2. The welding jig is made of transparency'.
welding
jig at the
sensor
and orifices.
are
ance
plastics
of the acrylic
sensor.
made as described in the following section. of the
Cross-section mid-length.
of the assembled welding jig.
using a thermistor
to a personal
Shape and dimension of the acrylic welding jig.
measuring
Fig.4
Fig.2
in CO, Laser Beam Welding (2nd Report)
The
as shown in Fig. 5, in the
high precision absorption
range of each thermistor
resistance
of the thermistor
was calibrated
thermometer.
by comparing
is 10 to at each with a
In the following study, the
efficiency of EB welding in a high vacuum,
which is the most typical high energy density welding, is going to be measured also for comparison. For that reason the welding jig is so designed and made that the jig can be used in a high vacuum modification. 2.2
Welding
chamber
without
specimen
middle of the hole where two orifices are placed to mix the outlet supplied
(warm)
water
by Shibaura
flow.
Electronic,
The thermistors and
were
the guaranteed
The welding specimens steel
were made of SM400A mild
(C: 0.15, Si : 0.14, Mn : 0.94 mass%)
and capital
溶接学 会論 文 集
第17巻(1999)第4号
Fig.7 Fig.6
Shape
and dimension
letter T-shapes necessary
of the welding
Change pattern of water temperature-rise (Defined as outlet temperature minus inlet temperature).
specimen .
were adopted as shown in Fig. 6. It is
that the welding heat which is absorbed
the welding specimen during welding is carried
into
away by
Then
bead-on-plate
started.
The
welding
several
welding specimen should be small and the water-cooled
the temperature
area should be large.
ture
And also the deformation
of the
length.
The
minus
will be no water leakage between
MT,
and the rubber packings The
cross
section
of the
becomes a T-shape.
and welding conditions demagnetized
welding
Thickness
was 10 mm but it is changed water temperature
the specimen surface
in a high vacuum.
with the welding
so that a desirable EB welding
laser beam welding
received
inlet
value
thus
FR and WT as shown
The principle the same
method
pattern
Measurement
is shown
of
tempera-
in Fig . 7.
The
DT, and values
of
e is absorption
efficiency,
treat-
DT is average
temperature
of each experiment,
report;
where
To
some of
by TIG arc welding at the
are
/ V(V)•~I(A)•~WT(s)•~0.238846(cal/J)
for
surface
for the calculation
duration
I is arc current, by
replaced
beam
WT
water,
water,
V•~I
is
of cooling
for measurement,
of cooling
V is arc voltage,
laser
and some were stud-welded
is time
rise
LP
(laser
power
W)
in
case
of
welding,
is welding
time.
of the EB welding specimen.
and
calculation
of
absorption
3.
Measurement
of absorption
efficiency
in TIG arc
welding
The welding
specimen
were assembled
and the acrylic
using rubber
packings
welding
jig
and 18-8 type
Absorption measured Okada.
the two thermistors
and reported
were connected
to an A/D con-
and the digitized output signals were processed computer.
efficiency in TIG-DCEN
and
stainless steel bolts. The cooling water hoses were connected to the welding jig. The voltage signals from
by a personal
One example as outlet
in our previous
are
efficiency
verter
in
increases
in Fig. 7 are used for calcula-
All specimens
men to fix the specimen to the acrylic cover plate.
2.3
is each
ƒÃ= DT(•Ž)•~MT(s)•~FR(m3/s)•~1000(kg/m3)•~0.001(cal/kg•Ž)
FR is flow rate
directly on the surface
is started.
and the equation
as described
of
There are bolt-holes in the welding speci-
of the specimen
water
is defined
temperature,
MT
backside
welding
in
120 to 200 mm
outlet
of the temperature-rise
8 ,um Rmax.
the bolts were tack-welded
of
and specimens
shot-blast
the slit-opening somewhat
it is from
rise, which
ment before welding to achieve the surface roughness of
comply with the objective
but
after
through varies
tion of F.
specimen
t in the original design
rise is obtained.
before
length
temperature
seconds
average
welding
bead
experiment,
the cooling water flow quickly and almost completely . To achieve this objective, the heat capacity of the
specimen during welding should be small so that there
495
the absorption authors DCEN
reported
previously
In their study, Hiraoka
arc welding was by
Hiraoka
and
and Okada measured
efficiency in stationary
TIG arc welding
that it was in the range of 85-90% . The measured the absorption efficiency in TIG-
arc
welding
using
the
above-mentioned
new
研究論文
496
Tomohiko
SHIDA
et al.:
Measurement
of Beam Energy Absorption
Fig.9 Fig.8
Appearance
measuring
system.
of setup
except
to
the improved
Absorption
efficiency
in TIG-DCEN
arc welding.
of TIG arc welding.
The welding
Fig. 8 is identical
in CO,. Laser Beam Welding (2nd Report)
that
of
measuring
setup
which
is shown
Hiraoka's
Cooling water
in
Four values
experiment
four
system.
flow rate : approx. 50 L/hour.
of absorption
experiments
efficiency
: namely
86.5,
were obtained 83.0,
89.3
from
and
86.9%
respectively. 3.1
Stationary
TIG arc
on a water-cooled
copper
plate 3.3
Stationary tungsten
TIG-DCEN
electrode
(3.2 mm in diameter)
cooled copper plate welding jig. Arc
current
Arc voltage Arc
length
Tip
angle
arc was ignited between
(1.5 mm in thickness)
The welding conditions
Moving
TIG arc
and a water-
Bead-on-plate
placed in the
steel specimen
are as follows :
in the experiments.
: 10 V,
obtained
tungsten
electrode
ted by Hiraoka
50 or 100 L/hour.
When the arc is ignited, the temperature increases
and sometime
moment,
measurement
efficiency
The values of absorption
Results of experiments
: 45deg,
Cooling water flow rate : approx.
this
jig.
in section 3.2 was also used
from five experiments
summarized
during
in the welding
efficiency
were 92.2, 94.1, 93.8, 89.
1 and 99.1% respectively.
: 3 mm,
between
steel plate
welding was made on a SM400A mild
Welding condition described
Shielding gas flow rate : Ar 10 L/min,
difference
on a mild
(t=10 mm) placed
: 100 A,
of the
welding
the
later
is started.
The
inlet and outlet
stationary
condition
is calculated.
Three
efficiency were obtained
of outlet water
is stabilized.
At this
temperature
water
is recorded
and
values
from three experiments
: name-
3.1, 3.2 and 3.3 are
in Fig. 9. The absorption
efficiencies repor-
et al.') are in the range of 85-90%.
The
values obtained in our experiments are in the range of 83 -94% except 99.1% which is apparently a result of unclarified
measurement
independent surement
error,
experiments
As a conclusion,
absorption of absorption
in sections
and agreement
of two
is almost good.
it is clear that the developed
mea-
method and the welding jig has passed the first
step of check and evaluation.
ly 92.4 (at 101.6 L/h), 86.9 (at 54.45 L/h) and 84.5% (at 4.
53.72 L/h) respectively. 3.2
Moving
TIG arc
on the water-cooled
copper
TIG arc was moved on the same water-cooled plate placed in the welding jig. are as follows :
Measurement
of absorption
ing in a high
vacuum
copper
The welding conditions
Electron typical
: 100 A, : 10 V,
reported
Shielding
tungsten
aluminum
gas flow rate
electrode
: Ar 10 L/min,
Welding speed : 100, 150 mm/min, Bead
length : 120 mm,
: 45deg,
density
into a base metal
voltage
: 3 mm,
energy
in a high vacuum
with
current
of the
welding
compared
Arc
angle
beam
high
Arc
Tip
in EB weld-
plate
absorption
Arc length
efficiency
tion
tem
beam
to be in the range alloy".
efficiency
measured
laser
to verify
welding.
is often
Electron
beam
in the past and
of 80-95%"
or 92-97%
welding
experiment,
in a high
the above-mentioned
the system
which
was studied
In the following
of EB
using
welding
is the most
performance.
vacuum
measurement
for
absorpwas sys-
溶 接 学 会 論 文 集
4.1
Preparation
第17巻(1999)第4号
of measurement
in EB welding
in a 5.
high vacuum A
high
Mitsubishi
The
confirmed setting to
experiments,
bolts
problem.
and
The at
cooling
avoid
the
of
cooling jig
to
of
rate water
in the
setup
in
the
measuring
Experimental
Accelerating
voltage
Beam
conditions
L/hour jig.
vacuum
Fig.
Pressure
position in
: Df =320 the
chamber
mm,
:
ments.
He shielding gas is supplied through
The
These
identical to the values reported able with another
report"
racy of measurement
Fig.10
The welding chamber.
100 L/hour were 95.
are almost
twice
power
setting
which
accuracy
in reference
and agree-
by comparing
with the accu-
in TIG arc welding.
jig setup
in the high vacuum
the
(1)
4 kW
is
The focus
a
was
welding
as shown later in Fig. 17.
the
power
laser
machine
settings
hand-hold
and type
within •}5%).
were
made
at
was
used
for
Deviation
Experiment
Fig.11
from
using
CO, laser
The
welding
at
value
average
5.2
and reported"
power
brated
efficiency.
values
the nozzle
direction of the focusing beam.
output
average
efficiency obtained
trans-
position of the laser beam and relation between the focus position and the depth of penetration were sepa-
measurements
: 200 mm,
The values of absorption
was used in the
This laser machine is of a 3-axial
to the coaxial
down-slope
ab=1.03,
flow rate : approx.
Electric
(PURE: Phase Unified REsonator, trade name). A ZnSe lens of 254 mm focal length is used in all experi-
: 2•~10-2Pa,
4 and 97.9% respectively.
system is shown in Fig. 11. A 6 kW CO2 laser
verse flow type and emits the PURE mode laser beam
Bead
Cooling water
beam
layout of the CO2 laser machine and the
made by Mitsubishi
Welding speed : 1000 mm/min, length
in CO2 laser
10
welding
were not used), Focus
measure-
experiments.
are as follows
and
a good
by using the developed
of measurement
rately measured
(up-slope
to make
welding
to
: 69.5 kV,
current : 50.2 mA
Preparation
machine
plate and measuring
possible
experi-
system.
measuring
was
result of EB welding on a mild steel
The welding
it is quite
The general
chamber.
4.2
from the above-mentioned
for CO2 laser beam
5.1
welding,
100
clear
welding
specimen
welding high
beam
leakage
during at
in CO, laser
with
water
fixed
that
ment
cup
specimens
welding
was
ments
(70 focus
Faraday
minimize
the
kW
the
efficiency
welding
It has become
Throughout
melting-through
flow
welding
the
power.
welding
used
35 beam
and
using
T-shaped
avoid
water
boiling
shows
to
the
of absorption
by The
is
of
method,
EB
made
experiment.
machine
test
exact
thickness
13 mm
the
the
measured
were
machine
position
ab
the
the
stud-welded
fixed
the
was
know
in
of
exact
by
method
welding
used
power
mA).
current
EB
was
output
kV•~500 was
type
Electric
maximum
Measurement beam
vacuum
497
of less
each
than
beam
once
power Three
each
power
cali-
at
5 kW
probe
(of
independent setting
calculation measured
was
of power
and
the
absorption level
from
1%.
welding
on a mild
steel plate
conditions
in this experi-
No. 1 and measuring
General layout of the COz laser measuring system.
machine
and the
研 究論文
498
ment
are
as
Tomohiko
follows
SHIDA et al.: Measurement of Beam Energy Absorption in CO, Laser Beam Welding (2nd Report)
:
Laser power : 4 kW nominal
(calibrated
Focus
position
the surface,
Laser
nozzle
: 2 mm below distance
: 5 mm
above
3923 W),
the surface,
Shielding gas : He 15 L/min, Welding speed : 500 mm/min, Cooling
water
flow rate
The experimental of absorption
: variable
result is shown in Fig. 12. The values
efficiency
stay in the range
above the flow rate of 20 g/s flow rate
is below
15 g/s
(72 L/hour).
(54 L/hour),
efficiencies fluctuate widely.
of 80-87% When the
the absorption
The phenomenon
is attrib-
utable to boiling of water in the cooling channel
Fig.12
Absorption efficiency in CO, laser beam welding (Effect of cooling water flow rate).
Fig.13
Absorption efficiency in CO, laser beam welding (Effect of shielding gas flow rate and welding speed).
of the
welding jig. (2)
Experiment
No. 2
In the experiment
No. 2, effects
of the shape
of slit
opening of the welding jig, flow rate of He shielding gas and welding measuring Laser
speed were evaluated.
conditions power
: 4 kW
Focus
position
Laser
nozzle
The welding
in this experiment
and
are as follows :
nominal,
: 2 mm
below
distance
the
surface,
: 5 mm above
the surface,
Shielding gas : He 15, 30, 45 L/min, Welding
speed : 500, 1000 mm/min,
Thickness
of the
Cooling water
specimen
: 10 mm,
flow rate : approx.
welding
20 L/hour
mm acrylic block in the water
with 10
channel
It was found that the shape of the slit opening had little effect on absorption
efficiency.
The experimental
is shown in Fig. 13. The values of absorption
result
efficiency
are in the range of 72-81% and not affected by the flow
Focus
position
: 2 mm
below
Laser
(3)
Shielding gas : He 15, 30 L/min,
No. 3
In the experiment water
Nos. 1 and 2, boiling
in the cooling
channel
was
of cooling
observed.
When
boiling occurs, water flow is blocked for a moment and fluctuates. cooling increase
It is effective
water
to reduce
causes decrease
to increase
the flow rate
the boiling.
However
of the maximum
of that
of tempera-
ture rise at the same time and thus reduces sensitivity measurement.
of
For this reason the flow rate of cooling
water is fixed at 100 L/hour in the following experiment No. 3. Thickness
t of the welding specimen was adjust-
with welding speed , and depth of the cooling channel in the welding jig was also adjusted to
1 mm
above
the
surface,
rate of He shielding gas. EXperiment
and
nozzle
distance
: 5 mm above
the surface,
Welding speed : 500, 1000 mm/min, Thickness
of the specimen : 17 mm (500 mm/min),
10
mm (100 mm/min), Cooling
water
flow rate : approx.
acrylic block in the water The
experimental
result
100 L/hour
with
channel is shown
in Figs.
14 and
15.
The values of absorption efficiency are in the range of 74 -78% for the focus position of -2 mm below the surface (Fig. 14). When the focus position is at +1 mm above the surface, absorption efficiency is somewhat lower
ed in accordance
than this value and in the range of 65-71%
become
(4) Experiment No. 4 In the experiment No. 4, the effect of focus position on
The ment
7.5 to 8.0 mm. welding
and measuring
are as follows
conditions
in this experi-
:
Laser power : 4 kW nominal
the absorption
efficiency was investigated.
(Fig. 15).
In this exper-
iment the laser power is fixed at 5 kW (nominal value) (calibrated
3801 W) ,
so that the result is directly compared
with the result of
溶接 学会 論 文集
our
Fig.14
Absorption efficiency in CO, laser beam welding (Effect of shielding gas flow rate, focus : -2 mm).
Fig.15
Absorption efficiency in CO, laser beam welding (Effect of shielding gas flow rate, focus: +1 mm).
previous
machine.
experiment
The welding
experiment
using
Laser
nozzle
CO,
conditions
laser in this
Fig.16
Absorption efficiency in CO, laser beam welding (Effect of focus position).
Fig.17
Penetration
(calibrated
5572 W),
the surface,
: 5 mm above
and dimension
compared.
lowered below the surface
of the specimen.
This trend
to the data on pene-
depths in the published reference
on mild steel plates All welding
was
(Fig. 17). The
experiments,
the
obtained
efficiency for TIG-DCEN
values
reported
values in the references.
the developed measurement
He shielding gas are changeable
Discussions
a new
As the results of of
absorption
well with previously This means that
The values of absorption efficiency obtained by abovementioned experiments for CO, laser beam welding in conditions.
above,
and
by bead-on-plate
method is reliable and appli-
6.
described
Using the new
arc welding and EB welding in
a high vacuum agreed considerably
cable to CO, laser beam welding.
of experiments
to over-
were measured
made
difference of absorption efficiencies between Ar shielding gas and He shielding gas is not appreciable.
In this series
as well as the
efficiency for TIG-DCEN
welding on a SM400 mild steel plate.
as the focus position is
and the data in Fig. 16 correspond tration
100 L/hour
result is shown in Fig. 16. The values
efficiency decrease
The shape
arc welding, EB welding in a high vacuum and CO, laser beam welding
of absorption
and used.
were also re-examined
method, values of absorption
the surface,
focus position.
come problems in the previous report".
Welding speed : 1000 mm/min, The experimental
of various
of the welding specimen system
Shielding gas : He 30 L/min, Ar 30 L/min, Cooling water flow rate : approx.
depth
acrylic welding jig was developed measurement
6, 2, 0 mm below distance
same
:
Laser power : 5 kW nominal position:
the
and measuring
are as follows
Focus
499
第17巻(1999)第4号
The absorption
depending
on welding
efficiency is in the range of
72-87% within our experimental
conditions
of 4-5 kW
laser
Tomohiko
研究論文
500
power,
0.5-1.0 m/min
SHIDA et al.: Measurement of Beam Energy Absorption in CO2 Laser Beam Welding (2nd Report)
welding
speed,
bead-on-plate
the focus
position at 2-0 mm below the surface, He shielding gas 15-45 L/min. and bead-on-plate welding on a SM400
(3)
The
From
data
maximum
ciable
of Figs. 16 and
17 it is understood
depth of the moving
absorption
difference
He shielding
mild steel plate. follows ; when the depth of penetration of beam
energy
on a SM400
of absorption
mild steel plate.
efficiencies
gas and Ar shielding
in our experiments.
ACKNOWLEDGEMENT:
is increased,
is also increased.
This
The authors
would like to express
sincere thanks to
phenomena is probably attributable to multi-reflections and increased absorption of the beam energy in the
the following persons for their contributions
key-hole.
the National
The above-mentioned
values
of absorption
for CO, laser are by approximately those for TIG-DCEN than those
0-10% lower than
in a high vacuum.
difference of approximately mainly
to formation
10-20% maybe
above the keyhole and partly
to reflection
of the laser
is always larger for gas.
efficiencies between
in Fig. 16. This means that
an amount
energy, which is once absorbed
7.
DCEN
newly
values arc
welding,
and CO2 laser were
developed
welding
does not
ably
previously
well
with
references',".
This
measurement
The
method beam
absorption
for
TIG-
steel
The obtained
for TIG-DCEN
in a high
vacuum
that
is reliable
plates
1)
2)
4)
6)
consider-
values the
5)
in the
developed
and applicable
to
7) 8)
welding. efficiency
of CO, laser
beam
weld-
ing is in the range of 72-87% within our experimental conditions of 4-5 kW laser power, 0.5-1.0 m/min. welding speed, the focus position at 2-0 mm below the
surface,
He shielding
gas
Mr.
of Ibara-
to Production
of Hitachi, Ltd. (TIG arc specimens)
of Hitachi,
and
Ltd. (Finan-
effort and help from Mr. M. Mr. H. Fuchida
during experiments
and Mr. T. are also quite
References
values
arc welding
agreed
reported
means
(Ph. D. student), (ex-students)
(Technicians
of welding
Laboratory
Dedicated
University),
thanks
of
Mr. Y.
appreciated.
in a high vacuum on mild
and compared. efficiency
and EB welding
CO, laser
Research
cial support).
form
water-calorimetric efficiency
EB welding
Institute
Hitachi
of the specimen.
beam
measured
of absorption
(2)
(which
of absorption
Training
for preparation
3)
the
method,
Also sincere
welding
trans-
Conclusion
(1) Using
Technology
of Ibaraki
and Mr. M. Ohtani
ki University).
for Metals),
of laser beam
in a scattered
heating
mean melting)
Y. Yasuzawa
Hirano
: Mr. G. Asai (Technician Institute
(Chief technician
as shown
is consequently
ferred on the surface of the specimen necessarily
But the
into Ar gas and metal
vapor plume above the keyhole, to general
Miyazaki
Research
and support
He shield-
ing gas and Ar shielding gas is not appreciable
and contributes
plume
to conduct the experiments
Oguma
gas than for Ar shielding
of absorption
vapor
surface.
In Fig. 17, the depth of penetration difference
This
attributable
of gas and metal
beam from the specimen He shielding
efficiency
arc welding and by 10-20% lower
for EB welding
between
gas is not appre-
as
(that means the
key-hole)
welding
15-45 L/min.
and
9)
Tarui, T., Sakamoto, H. and Shibata, K.: Energy coupling between materials and beam in laser welding (2nd report), Preprints of the National Meeting of JWS, No. 55, Oct. 1994, pp. 40-41 (in Japanese). Tarui, T., Sakamoto, H. and Shibata, K.: Energy coupling between materials and beam in laser welding (3rd report), Preprints of the National Meeting of JWS, No. 56, Mar. 1995, pp. 44-45 (in Japanese). Maruo, H., Miyamoto, I., Kawabata, F. and Arata. Y.: Laser welding of metal, Journal of the Japan Welding Soc., Vol. 50 (1981), No. 4, pp. 404-409 (in Japanese). Dausinger, F., Beck, M. et al.: Energy Coupling in Surface Treatment Processes, Journal of Laser Applications, Summer/Fall 1990, pp. 17-21. Shida, T. and Terauchi, T.: Measurement of Beam Energy Absorption in CO, Laser Beam Welding, Quarterly Journal of JWS, Vol. 14, No.3, pp. 477-482 (1996). Hiraoka, K. and Okada, A : Heat input characteristics in TIG arc welding with Ar or Ar-He mixture shielding gas, Report presented to 87th Welding Arc Physics Research Committee of JWS, 23rd July 1987 (in Japanese). AWS ed.: Welding Handbook 8th ed., Vol. 1, p. 69 (1987). Irie, H., Hashimoto, T. et al.: Investigation on factors influencing weld penetration depth in electron beam welding, Transactions of National Research Institute for Metals, Vol. 21, No. 2, pp. 8-18 (1979). Tsukamoto.
S.. Hiraoka.
K. et al.:
Effect of plasma
forma-
tion on penetration depth in C02 laser welding, Preprints of the National Meeting of JWS, No. 61, Sept. 1997, pp. 330-331 (in Japanese).
