66
CHINA
WELDING
Vo
l. 20 No.4 December 2011
Laser welding
of
6061
aluminum alloy sheet with surfactant
Shi
Wenli
晤
,
Yang Lijun , Wang Jinjie
and
Wang
Xia
α
bo
石文玲,杨立军,王金杰,王小博**
•
Abstract
Aluminum
α
lloy
shows
10
町
absorption
to laser for its
essent
ω
1
high
r
矿
lection
property.
ln
this
paper
,
α n
active
1
α
ser
welding process
is
adopted to weld
6061
aluminum alloy with the halide surfactant coated on sheet
su
庐
ce
to improve the
welding quality. The sheets with
surfi
α
ctant
α
陀
welded
under
α
series
of
welding parameters
of
laser
power
αnd
welding speed
while the plasma
plum
臼
in
the welding
process
α
re
recorded by high-speed
cα
mera.
Then
α
metallographic
analysis
and
a
transverse tensile test are implemented
to.
ω
sess
the sheet butt joint property. The
e.
αz
哝
;p
enm
阳
en
附
t
归
s s
执
ho
仰
w
t
仇
h
αωt t
加
he
1
即阴
ve
口叩
eld
de
句
Eφpμ
th
is
deepened
and
the plasma plume
臼
sma
阳
α
all
扣如
e
旷
r
t
山
Ud
础
iut
仇
h
s
阳
u
':,
扩
fa
町
ω
ct
ωα
nt. A well formed
u
阴
v
时
y
增
eld
of
1
mr
丑
nm-t
仇
hi
凶
ckr
阳
B
回
ess
s
必
heet
of
6061
α
luminum
alloy can
be
obtained under laser power
of
920 W, welding speed
of
7 m
m/
s,
zero
d.
呐
cusmg-
α
mount
and α
n
argon shielding
gω
flow
of30
νmm.
Key words surfactant ,
6061
aluminum
alloy
, laser welding , plasma plume
o
Introduction
Aluminum
alloy
has
attracted
great
attention
in
indus-
trial
application
for
its
favorable
high
stren
gI
h-to-weight
ra-
tio.
But
the
laser
welding
of
aluminum
alloys
encounters
great
difficulties
due
to
their
high
reflection
[门.
Some
methods
,
such
as
applying
dark
substance
or
roughening
the
metal
surface
, were
used
to
reduce
the
reflection
of
a-
luminum
alloys ,
but
the
improvement
is
limited
[2]
•
Surfactants
can
be
applied
in
welding
to
improve
welding
quality.
A
number
of
studies
regarding
flux-assis-
ted
welding
have
been
published
,
such
as
TIG
welding
and
laser
welding
of
stainless
steel
and
magnesium
alloys
in
which
the
surfactant
was
adopted
to improve
the
fluidity
of
liquid
metal
in
weld
pool
and
enhance
the
arc
energy
density[34].
The
studies
on
active
laser
welding
of
aluîni-
num
alloys
have
been
rarely
reported.
In
this
paper
,
an
active
laser
welding
process
with a
kind
of
hal
i<
~e
surfac-
tant
to
reduce
the
laser
reflection is
proposed
to weld
6061
aluminum
alloy
sheets
,
and
the
action
mechanism
is
dis-
cussed.
'
1
Design
of
surfactant
Surfactants
are
the
substances
helpful
to
deepen
weld
depth
and
improve
weld
quality
in
welding
process.
In
this
work ,
chloride
and
fluoride were
selected
as
essential
component
of
surfactant
which
was
played
a significant role
in
laser
welding
of
6061
aluminum
alloy.
In
the
brazing
of
aluminum
,
the
flux
composed
by
chloride
and
fluoride
can
remove oxide film
and
protect
the
weld. Using this
kind
of
brazing
technique
for
reference
, a
supersaturated
solution
prepared
with
NaCl
, ZnCI
2
, LiCl
and
KF
in
a
certain
pro-
portion was
used
as
a
surfactant
in
laser
welding
of
alumi-
num
alloy.
If
the
sheet
is
overlaid
with
the
surfactant
,
the
sheet
surface
will
become
rough
and
the
absorptivity
of
la-
ser
will
increase
as
the
physical
characteristic
of
surfactant
is
different
from
aluminum
alloy.
The
molten
surfactant
floating
on
the
weld
pool
surface
will
not
only
protect
the
weld
pool
surface
but
also
change
the
surface
tension
of
weld pool.
In
the
surfact
且
nt
of
this work ,
the
mass
ratio for LiCl
and
KF
are
25
%…
50%
,
respectively
, while NaCl
and
ZnCl
2
are' totally
less
than
20%
,
less
than
129
毛
for
each.
* This project
is
supported
by
Natural Science Foundation
of
Tianjin
(I
IJCYBJC06100) and Science &
Technology
Pillar
Program
of
Tianjin (IOZCKFSF00200).
**
Shi
Wenling ,
Yang
Lijun ,
Wang
Jinjie and
Wang
Xiaobo
, School
of
Materials Science and Engineering , Tianjin University , Tianjin ,
300072.
Yang
Lijun , Tianjin
Key
Laboratory of Advanced Joining Technology , Tianjin University , Tianjin , 300072.
Yang
Lijun ,
Corresponding author , E-mail: tdyljabc@163.com