Saw
Content
Submerged Arc Welding
(SAW)
1
Submerged Arc Welding
1. Introduction
2. The SAW process
1. Introduction
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
2
Increasing deposition rate
SAW - 1. Introduction
SAW
MIG / MAG
(GMAW)
High productivity
Flat position
Manual
Versatile
MMA
(SMAW)
Productivity
Easy automation
TIG
(GTAW)
Laser
(LBW)
High speed
Accurate
Quality
3
SAW - 1. Introduction
SMAW
+ Versatile
+ All kind of preparation
+ All positions
- Low deposition rate
GTAW
+ High quality
+ All positions
- Very low deposition rate
4
SAW - 1. Introduction
GMAW
/ FCAW - gas (Outer shield)
+ All positions
+ Good deposition rate
- Need shielding gas
FCAW
- ss (Inner shield)
+ All positions
+ Typical for outdoor job
+ Good deposition rate
- Narrow operating range
5
SAW - 1. Introduction
SAW
+ High deposition rate
+ Very reliable
+ High quality welds
+ Deep penetration
+Environmental/ergonomic impact (no fumes or radiation)
- Only in flat position (and 2G with specific installation)
6
Submerged Arc Welding
1. Introduction
2. The SAW process
2. Thé SAW procès
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
7
SAW - 2. The process
Control box
Wire
Flux hopper
Power source
Cables
8
Welding head
SAW - 2. The process
• The welding current :
• CV power source for
wire up to 2.4mm, and for
Tiny Twin
• Higher WFS
• NA3 or NA5 control box
• The regulation is made
by the out put current only
9
SAW - 2. The process
• The welding current :
• CC (or VV) power
source for wire down to
2.4mm
• Lower WFS
• NA3 control box only
• The regulation is made
by changing the WFS
when voltage variations
occur
10
SAW - 2. The process
• The welding current :
•Reminder
•CC (or VV) for large puddle
• CV for small puddle
11
SAW - 2. The process
• How SAW works
Wire
Air
Solid slag
Flux
Molten slag
Arc
Solid weld metal
Molten pool of electrode,
flux and base metal
12
Submerged Arc Welding
1. Introduction
2. The SAW process
3. Main variables effect
3. Main variables
effect
4. Welding defects
5. Consumables
6. Reminder
13
SAW - 3. Main variables effect
• The main variables :
• Welding current - I (Amps)
• Voltage - U (Volt)
• Wire diameter - D (mm)
• Travel Speed (cm/min)
•Polarity (DC+ or DC- or AC)
14
SAW - 3. Main variables effect
• The secondary variables :
• Welding current type (CV or CC)
•Flux height
• Electrical Stick Out - ESO (mm)
• Ground position
• Joint preparation
• Backing
• Slope
15
SAW - 3. Main variables effect
• The special variables :
• Circular weld
• Fillet weld
• 2G weld
16
SAW - 3. Main variables effect
• The welding current :
Deeper penetration
• Increasing I
Higher current density
Higher WFS
Higher deposition rate
Erratic arc
Undercut
• Too much I
High narrow bead
17
SAW - 3. Main variables effect
I
I
I
The maximum penetration in one pass
22 mm (1100A)
18
SAW - 3. Main variables effect
• Compared current density (CD Amps/mm2):
diam
Smm2
I mini
CDmin Imax
CDmax
0.6
0.283
40
141
130
460
0.8
0.503
50
99
230
457
1.0
0.785
70
89
280
357
1.2
1.131
80
71
350
309
1.6
2.011
160
80
450
224
2.0
3.079
180
58
450
146
2.4
4.448
250
56
575
129
3.2
7.892
330
42
730
93
4.0
12.378 430
35
830
67
4.8
17.795 510
29
940
53
19
SAW - 3. Main variables effect
Reminder only:
From the previous table you can consider the following:
For a single electrode:
I mini = 100 x wire diameter
I maxi = 200 x wire diameter + 50
20
SAW - 3. Main variables effect
•Arc length = f( Voltage)
Wire and
contact tip
U0=0
L0=0
Short circuit
U1
U2
L1
L2
U1 < U2
L1 < L2
21
SAW - 3. Main variables effect
• Voltage : be careful of the drop
Control box
U and I
U from the control box =
U2
U1 + U2 + U3
U1
With U3 = other drop of voltage
(connections, cable length…)
22
SAW - 3. Main variables effect
• The voltage :
Longer arc length
• Increasing U
Little change only in the
penetration
Wider bead
Higher flux consumption
Less burn through
23
SAW - 3. Main variables effect
L1
U
U
U
L3
L2
24
SAW - 3. Main variables effect
• The voltage :
Undercut
• Too much U
Increase magnetic blow
susceptibility
Be careful with active flux
(over alloying with Mn and Si)
• When you increase the travel speed, the
voltage have to be as low as possible
25
SAW - 3. Main variables effect
45,0
40,0
Voltage
2.4
3.2
4
5.5
4.8
2
35,0
30,0
25,0
20,0
0
200
400
600
Welding current Amps
26
800
1000
1200
SAW - 3. Main variables effect
• Wire diameter :
Less penetration at a given
current
• Increasing D
Arc more difficult to start
Less burn through risk at
low current (poor fit up)
Higher acceptable welding
current
27
SAW - 3. Main variables effect
D1
D2
P1
P2
Same welding current
D1 < D2
P1 > P2
28
SAW - 3. Main variables effect
• The travel speed :
Less penetration
• increasing the TS
Smaller bead
Decrease the wetting
increase tendency to :
undercut
arc blow sensitivity
porosity
uneven bead shape
29
SAW - 3. Main variables effect
• The travel speed :
• Excessively slow speeds produce
•“Hat-shaped” bead that is subject to
cracking
•Flash through
•Large molten pool giving rough
bead, spatter and slag inclusions
•Less penetration
30
SAW - 3. Main variables effect
• Cracks problem
• Too much voltage or too slow travel speed
“Hat-shaped” bead
Concave bead
31
SAW - 3. Main variables effect
• The travel speed :
• Electrode angle and penetration
V
P0
P1
3 to 5 °
V
P2
V
P3
32
SAW - 3. Main variables effect
Penetration will change if you
change :
Penetration
Maximum
penetration
Welding current
ESO
Travel speed
Preparation
Wire diameter
Slope
Polarity
Welding flux
I3
I2
I1
I 1 < I2 < I 3
25/30
Travel speed
45/50
cm/min
33
SAW - 3. Main variables effect
• The Flux height and the Electrical Stick Out :
Wire and
contact tip
Flux
ESO
Flux
height
34
SAW - 3. Main variables effect
• The Flux height :
• Just enough to cover the arc light
Flashes
• Height too low
Porosity
Suppression of the
arc
• Height too deep
Narrow bead
Poor slag removal
35
SAW - 3. Main variables effect
• The Flux height :
• For single wire and Twin Arc
• 20 to 35 mm
•For Tandem or multi arcs
• 30 to 50 mm
36
SAW - 3. Main variables effect
• The Electrical Stick Out :
• For single wire, tandem, or multi arcs
applications
• ESO = 20 to 30 mm
•This length have to be defined regarding
Welding current
Wire diameter
Travel speed
Weld pool size
•Examples : small weld pool ESO = 20mm or less
•large weld pool ESO = 30 mm or more
37
SAW - 3. Main variables effect
• The Electrical Stick Out :
• Increasing the ESO will Increase the deposition
rate.
• Why ?
Electrical resistance
• R = x (l/s) with =resistivity, l=length, s=wire
section
• P = R x I2 with P=absorbed power, I=welding
current
• But be careful, you will have to increase the
voltage because of the drop in the wire (U = RI)
38
SAW - 3. Main variables effect
D=3,2 DC +
25,0
SO 125mm
20,0
SO 75mm
k g / he ure
15,0
SO 25mm
10,0
5,0
0,0
300
350
400
450
500
550
600
Am ps
39
650
700
750
800
850
900
SAW - 3. Main variables effect
• The Polarity :
•AC
Most resistant to arc blow
Greater penetration
• DC +
Better resistance to porosity
Smother weld
Higher deposition rate +30%
• DC -
Less penetration
To get a similar bead shape,
increase the voltage by 4 V
40
SAW - 3. Main variables effect
• The Polarity :
Better wetting
DC -
DC +
2/3
1/3
2/3
DC +
1/3
DC -
Greater penetration
• DC - applications :
Hard surfacing
Fillet weld
41
Filling
SAW - 3. Main variables effect
• The Alternating Current AC :
Polarity change 100
times / sec. (50Hz)
+
• Compared to DC+ :
Less penetration
-
Starting more difficult
To get a similar bead shape, increase the
voltage of 1 to 3 V
• Applications :
Higher deposition rate
+15%
Tandem
Arc blow troubles
42
SAW - 3. Main variables effect
1/3
1/2
2/3
2/3
1/2
1/3
DC +
AC
DC -
Deposition rate
+15%
+30%
43
Submerged Arc Welding
1. Introduction
2. The SAW process
4. Welding defects
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
44
SAW - 4. Welding defects
• Porosity are coming from :
Poor steel (high sulfur content)
Organic contamination - oil
Rusty joint or wire ( moisture bond in the rust)
Contaminants in the flux (moisture, dirt and “mil scale)
Electrode contamination under unusual storage
Insufficient flux
Tack welds
Arc blow
Trapped flux
45
SAW - 4. Welding defects
• Cracks are coming from :
•Bead shape (see the “hat shaped” bead and the W / D
ratio)
•Steel analysis (see after)
•Hydrogen content of the weld metal (see after)
•Mechanical stress (see after)
•Arc blow
•Admixture
•Improper procedure (solidification cracking)
•Movement of joint
46
SAW - 4. Welding defects
• Cold cracks are coming from :
Overlap
Overlap of
of 33 Factors
Factors
Result
Result in
in High
High Risk
Risk
Situation
Situation
Hydrogen
Reducing
Reducing the
the Size
Size of
of the
the
Circles
Circles Decreases
Decreases Risk
Risk Zone.
Zone.
Stress
(Mechanical)
MicroStructure
(Material)
47
Submerged Arc Welding
1. Introduction
2. The SAW process
5. Consumables
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
48
SAW - 5. Consumables
• SAW is a combinaison of two consumables.
•It can be confusing, and result of that is a lack of
confidence in your product.
49
SAW - 5. Consumables:Flux
• How to choose the proper filler metal ?:
•A) Flux choice will be driven by :
•1)Base metal (stainless/non or low alloy)
•2)Single pass or multiple passes (non and low
alloyed steels only)
•2)Mechanical properties (impacts)
•3)Dedicated to one job or “universal “ product
in the workshop (optimisation)
50
SAW - 5. Consumables:Flux
• How to choose the proper flux:
•1)Base metal (stainless/non or low alloy):
•This will drive you to two different range of
products:
•Stainless :
P2000
•
P2000S
•
P7000 (Ni Base)
•Non & low alloyed : rest of the range
51
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
• 1)Single
pass / two run :
•What is it ?
•Two different kind of application
•High tech :2 passes (pipes)
•Low tech : one or 2 passes (sound weld at low cost)
52
SAW - 5. Consumables:Flux
Non & low alloyed steels, two run technique:
– 1)
Low tech
Main objective is sound welds at low cost
– Very often no or poor weld prep
• Oxy cutting + grinded edges
• Shear and grinded
Therefore we need an ACTIVE flux in
order to “clean the puddle
serie 7XX
53
SAW - 5. Consumables: Flux
•And In the 7XX family, how to choose it ?
•761 = Large weld puddle, low speed, resistance
to hot cracking
•780 = Because of is Medium Viscosity and high
freezing point It’s the best on roundabout
•782 = Because of is low viscosity and medium
freezing point it’s the best at high speed
54
SAW - 5. Consumables: Flux
•Q1) Therefore why don’t we use “7XX” fluxes everywhere ?
•A1)The Mn &Si will build up at each pass, therefore
multipass can drive to a very brittle weld.
•A2) Alloying depend on the voltage (non neutral fluxes)
55
SAW - 5. Consumables: Flux
Q2)“I
know some “single pass”
application with basic fluxes” ?
•A1) Definitely, but then the electrode chemistry
has to be adapted (Mo ,Mo Ti B or others).
•A2) Welding speed will be low and could probably
be optimized with an other type of fluxes.
56
SAW - 5. Consumables:Flux
Q3) Why not a fully basic flux for “high quality “ in single
or two run technique ?
57
SAW - 5. Consumables: Flux
Non & low alloyed steels, two run technique:
• 2) High Tech (pipes)
•Main objective is mechanical characteristics speed
and reliability
•Very clean and accurate weld prep
•Main concern will be:
•MICROSTRUCTURE
•(see the 9XX flux family)
58
SAW - 5. Consumables: Flux
Non & low alloyed steels:
• 3)Multipass :
We need a non active flux in order to control
the weld metal chemistry.
I.e alloys will be in the wire, tensile & yield will
depend on it.
In our LINCOLN range =
8XXX , P2XX, Mil 800H family
59
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
Basicity of the flux will drive the impact values
in multipass (but not the operability).
60
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
• 3)Multipass :
•860 : Very good operating characteristics, impact @ -20°c
•P230: Very good mechanical properties.Good operating
characteristics
•P240: Specific multipass flux.Very good mechanical ppt
Good slag removal if opening larger than 16mm
•8500: Very good mechanical properties and impacts even
in cap passes.Good operating characteristics
61
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
• 4)Multipass & / or single pass:
•We need a slightly active & neutral flux in
order to cover the all range =9XX family
But do not forget that if you can
cover everything, it’ a compromise.
9XX compromise impact of 8XX and
operability of 7XX
62
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
• 4)Multipass & / or single pass:
•960 = Slow speed, large puddles, impact @ 20°C.
Plates thickness from 25mm and up
•980 = Impact @-0°C, good with contaminated plates.
Welding speed can be higher than 960 . Thin gauge
plates
•995N = Specific application with LNS 140TB
•P223 = Good impact and because of his slag freezing
point and viscisity very good in spiral pipe mills
63
SAW - 5. Consumables: Electrodes
Non & low alloyed steels:
•1) Single pass / two run :
•L61 : impact @0°C Consider it as a reference
(higher alloy if scale or rust, lower alloy if organic contamination
•Mo addition will improve impacts:
64
SAW - 5. Consumables: Electrodes
Non & low alloyed steels:
•
Single pass / two run :
•Addition of Mo +Ti B for optimum impacts (LNS 140TB)
65
SAW - 5. Consumables: Electrodes
•Non & low alloyed steels:
•2) Multipass :
•Electrodes composition will depend on the
requested mechanical characteristics.
•It will be defined according the requirement
: yield, tensile, impacts, PWHT or not …..
66
Submerged Arc Welding
1. Introduction
2. The SAW process
6. Reminder
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
67
SAW - 6. Reminder
D=2,4 DC 25,0
SO 83mm
y = 0,0048x 1,2864
R2 = 0,998
20,0
y = 0,0047x 1,2552
R2 = 0,9989
kg / heure
15,0
y = 0,0072x 1,1468
R2 = 0,9979
SO 57mm
SO 25mm
10,0
5,0
0,0
300
350
400
450
500
Am ps
68
550
600
650
700
SAW - 6. Reminder
D=2,4 DC +
SO 83mm
18,0
16,0
y = 0,0008x 1,5154
R2 = 0,9997
SO 57mm
14,0
y = 0,0004x 1,6165
R2 = 0,9982
kg / heure
12,0
10,0
SO 25mm
y = 0,0036x 1,1896
R2 = 0,9915
8,0
6,0
4,0
2,0
0,0
300
350
400
450
500
550
Amps
69
600
650
700
SAW - 6. Reminder
D=3,2 DC +
25,0
SO 125mm
y = 0,001x 1,4841
R2 = 0,998
20,0
y = 0,0019x 1,3438
R2 = 1
kg / heure
15,0
y = 0,0011x 1,3751
R2 = 0,9977
10,0
SO 75mm
SO 25mm
5,0
0,0
300
350
400
450
500
550
600
650
Am ps
70
700
750
800
850
900
SAW - 6. Reminder
D=3,2 DC 30,0
SO 125mm
y = 0,0013x 1,4715
R2 = 0,9996
25,0
kg / heure
20,0
15,0
y = 0,0029x 1,3107
R2 = 0,9958
SO 75mm
y = 0,0057x 1,1708
R2 = 0,9999
SO 25mm
10,0
5,0
0,0
300
350
400
450
500
550
600
650
Am ps
71
700
750
800
850
900
SAW - 6. Reminder
D=4 DC +
25,0
SO 125mm
20,0
SO 75mm
kg / heure
15,0
SO 25mm
10,0
5,0
0,0
400
450
500
550
600
650
700
Am ps
72
750
800
850
900
950
1000
SAW - 6. Reminder
D=4 DC30,0
SO 125mm
25,0
SO 75mm
kg / heure
20,0
SO 25mm
15,0
10,0
5,0
0,0
400
450
500
550
600
650
700
Am ps
73
750
800
850
900
950
1000
SAW - 6. Reminder
SOUDAGE A L'ARC SUBMERGE
500
450
Vitesse de dévidage en cm /m n
400
350
Polynomial (2mm)
300
Polynomial (2,4mm)
250
Polynomial (3,2mm)
Polynomial (4mm)
200
Polynomial (4,76mm)
150
100
50
0
200,00
400,00
600,00
800,00
1000,00
Intensité en Am pères
74
1200,00
SAW - 6. Reminder
Basicity
of flux :
Basi. Index
–
–
–
–
Acid
<0,9
Neutral
0,9<BI<1,2
Basic
1,2<BI<2
Highly basic
<2
75
Melting range
1100°c /1300°c
1300°c/ 1500°c
>1500°c
>1500°c
(SAW)
1
Submerged Arc Welding
1. Introduction
2. The SAW process
1. Introduction
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
2
Increasing deposition rate
SAW - 1. Introduction
SAW
MIG / MAG
(GMAW)
High productivity
Flat position
Manual
Versatile
MMA
(SMAW)
Productivity
Easy automation
TIG
(GTAW)
Laser
(LBW)
High speed
Accurate
Quality
3
SAW - 1. Introduction
SMAW
+ Versatile
+ All kind of preparation
+ All positions
- Low deposition rate
GTAW
+ High quality
+ All positions
- Very low deposition rate
4
SAW - 1. Introduction
GMAW
/ FCAW - gas (Outer shield)
+ All positions
+ Good deposition rate
- Need shielding gas
FCAW
- ss (Inner shield)
+ All positions
+ Typical for outdoor job
+ Good deposition rate
- Narrow operating range
5
SAW - 1. Introduction
SAW
+ High deposition rate
+ Very reliable
+ High quality welds
+ Deep penetration
+Environmental/ergonomic impact (no fumes or radiation)
- Only in flat position (and 2G with specific installation)
6
Submerged Arc Welding
1. Introduction
2. The SAW process
2. Thé SAW procès
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
7
SAW - 2. The process
Control box
Wire
Flux hopper
Power source
Cables
8
Welding head
SAW - 2. The process
• The welding current :
• CV power source for
wire up to 2.4mm, and for
Tiny Twin
• Higher WFS
• NA3 or NA5 control box
• The regulation is made
by the out put current only
9
SAW - 2. The process
• The welding current :
• CC (or VV) power
source for wire down to
2.4mm
• Lower WFS
• NA3 control box only
• The regulation is made
by changing the WFS
when voltage variations
occur
10
SAW - 2. The process
• The welding current :
•Reminder
•CC (or VV) for large puddle
• CV for small puddle
11
SAW - 2. The process
• How SAW works
Wire
Air
Solid slag
Flux
Molten slag
Arc
Solid weld metal
Molten pool of electrode,
flux and base metal
12
Submerged Arc Welding
1. Introduction
2. The SAW process
3. Main variables effect
3. Main variables
effect
4. Welding defects
5. Consumables
6. Reminder
13
SAW - 3. Main variables effect
• The main variables :
• Welding current - I (Amps)
• Voltage - U (Volt)
• Wire diameter - D (mm)
• Travel Speed (cm/min)
•Polarity (DC+ or DC- or AC)
14
SAW - 3. Main variables effect
• The secondary variables :
• Welding current type (CV or CC)
•Flux height
• Electrical Stick Out - ESO (mm)
• Ground position
• Joint preparation
• Backing
• Slope
15
SAW - 3. Main variables effect
• The special variables :
• Circular weld
• Fillet weld
• 2G weld
16
SAW - 3. Main variables effect
• The welding current :
Deeper penetration
• Increasing I
Higher current density
Higher WFS
Higher deposition rate
Erratic arc
Undercut
• Too much I
High narrow bead
17
SAW - 3. Main variables effect
I
I
I
The maximum penetration in one pass
22 mm (1100A)
18
SAW - 3. Main variables effect
• Compared current density (CD Amps/mm2):
diam
Smm2
I mini
CDmin Imax
CDmax
0.6
0.283
40
141
130
460
0.8
0.503
50
99
230
457
1.0
0.785
70
89
280
357
1.2
1.131
80
71
350
309
1.6
2.011
160
80
450
224
2.0
3.079
180
58
450
146
2.4
4.448
250
56
575
129
3.2
7.892
330
42
730
93
4.0
12.378 430
35
830
67
4.8
17.795 510
29
940
53
19
SAW - 3. Main variables effect
Reminder only:
From the previous table you can consider the following:
For a single electrode:
I mini = 100 x wire diameter
I maxi = 200 x wire diameter + 50
20
SAW - 3. Main variables effect
•Arc length = f( Voltage)
Wire and
contact tip
U0=0
L0=0
Short circuit
U1
U2
L1
L2
U1 < U2
L1 < L2
21
SAW - 3. Main variables effect
• Voltage : be careful of the drop
Control box
U and I
U from the control box =
U2
U1 + U2 + U3
U1
With U3 = other drop of voltage
(connections, cable length…)
22
SAW - 3. Main variables effect
• The voltage :
Longer arc length
• Increasing U
Little change only in the
penetration
Wider bead
Higher flux consumption
Less burn through
23
SAW - 3. Main variables effect
L1
U
U
U
L3
L2
24
SAW - 3. Main variables effect
• The voltage :
Undercut
• Too much U
Increase magnetic blow
susceptibility
Be careful with active flux
(over alloying with Mn and Si)
• When you increase the travel speed, the
voltage have to be as low as possible
25
SAW - 3. Main variables effect
45,0
40,0
Voltage
2.4
3.2
4
5.5
4.8
2
35,0
30,0
25,0
20,0
0
200
400
600
Welding current Amps
26
800
1000
1200
SAW - 3. Main variables effect
• Wire diameter :
Less penetration at a given
current
• Increasing D
Arc more difficult to start
Less burn through risk at
low current (poor fit up)
Higher acceptable welding
current
27
SAW - 3. Main variables effect
D1
D2
P1
P2
Same welding current
D1 < D2
P1 > P2
28
SAW - 3. Main variables effect
• The travel speed :
Less penetration
• increasing the TS
Smaller bead
Decrease the wetting
increase tendency to :
undercut
arc blow sensitivity
porosity
uneven bead shape
29
SAW - 3. Main variables effect
• The travel speed :
• Excessively slow speeds produce
•“Hat-shaped” bead that is subject to
cracking
•Flash through
•Large molten pool giving rough
bead, spatter and slag inclusions
•Less penetration
30
SAW - 3. Main variables effect
• Cracks problem
• Too much voltage or too slow travel speed
“Hat-shaped” bead
Concave bead
31
SAW - 3. Main variables effect
• The travel speed :
• Electrode angle and penetration
V
P0
P1
3 to 5 °
V
P2
V
P3
32
SAW - 3. Main variables effect
Penetration will change if you
change :
Penetration
Maximum
penetration
Welding current
ESO
Travel speed
Preparation
Wire diameter
Slope
Polarity
Welding flux
I3
I2
I1
I 1 < I2 < I 3
25/30
Travel speed
45/50
cm/min
33
SAW - 3. Main variables effect
• The Flux height and the Electrical Stick Out :
Wire and
contact tip
Flux
ESO
Flux
height
34
SAW - 3. Main variables effect
• The Flux height :
• Just enough to cover the arc light
Flashes
• Height too low
Porosity
Suppression of the
arc
• Height too deep
Narrow bead
Poor slag removal
35
SAW - 3. Main variables effect
• The Flux height :
• For single wire and Twin Arc
• 20 to 35 mm
•For Tandem or multi arcs
• 30 to 50 mm
36
SAW - 3. Main variables effect
• The Electrical Stick Out :
• For single wire, tandem, or multi arcs
applications
• ESO = 20 to 30 mm
•This length have to be defined regarding
Welding current
Wire diameter
Travel speed
Weld pool size
•Examples : small weld pool ESO = 20mm or less
•large weld pool ESO = 30 mm or more
37
SAW - 3. Main variables effect
• The Electrical Stick Out :
• Increasing the ESO will Increase the deposition
rate.
• Why ?
Electrical resistance
• R = x (l/s) with =resistivity, l=length, s=wire
section
• P = R x I2 with P=absorbed power, I=welding
current
• But be careful, you will have to increase the
voltage because of the drop in the wire (U = RI)
38
SAW - 3. Main variables effect
D=3,2 DC +
25,0
SO 125mm
20,0
SO 75mm
k g / he ure
15,0
SO 25mm
10,0
5,0
0,0
300
350
400
450
500
550
600
Am ps
39
650
700
750
800
850
900
SAW - 3. Main variables effect
• The Polarity :
•AC
Most resistant to arc blow
Greater penetration
• DC +
Better resistance to porosity
Smother weld
Higher deposition rate +30%
• DC -
Less penetration
To get a similar bead shape,
increase the voltage by 4 V
40
SAW - 3. Main variables effect
• The Polarity :
Better wetting
DC -
DC +
2/3
1/3
2/3
DC +
1/3
DC -
Greater penetration
• DC - applications :
Hard surfacing
Fillet weld
41
Filling
SAW - 3. Main variables effect
• The Alternating Current AC :
Polarity change 100
times / sec. (50Hz)
+
• Compared to DC+ :
Less penetration
-
Starting more difficult
To get a similar bead shape, increase the
voltage of 1 to 3 V
• Applications :
Higher deposition rate
+15%
Tandem
Arc blow troubles
42
SAW - 3. Main variables effect
1/3
1/2
2/3
2/3
1/2
1/3
DC +
AC
DC -
Deposition rate
+15%
+30%
43
Submerged Arc Welding
1. Introduction
2. The SAW process
4. Welding defects
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
44
SAW - 4. Welding defects
• Porosity are coming from :
Poor steel (high sulfur content)
Organic contamination - oil
Rusty joint or wire ( moisture bond in the rust)
Contaminants in the flux (moisture, dirt and “mil scale)
Electrode contamination under unusual storage
Insufficient flux
Tack welds
Arc blow
Trapped flux
45
SAW - 4. Welding defects
• Cracks are coming from :
•Bead shape (see the “hat shaped” bead and the W / D
ratio)
•Steel analysis (see after)
•Hydrogen content of the weld metal (see after)
•Mechanical stress (see after)
•Arc blow
•Admixture
•Improper procedure (solidification cracking)
•Movement of joint
46
SAW - 4. Welding defects
• Cold cracks are coming from :
Overlap
Overlap of
of 33 Factors
Factors
Result
Result in
in High
High Risk
Risk
Situation
Situation
Hydrogen
Reducing
Reducing the
the Size
Size of
of the
the
Circles
Circles Decreases
Decreases Risk
Risk Zone.
Zone.
Stress
(Mechanical)
MicroStructure
(Material)
47
Submerged Arc Welding
1. Introduction
2. The SAW process
5. Consumables
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
48
SAW - 5. Consumables
• SAW is a combinaison of two consumables.
•It can be confusing, and result of that is a lack of
confidence in your product.
49
SAW - 5. Consumables:Flux
• How to choose the proper filler metal ?:
•A) Flux choice will be driven by :
•1)Base metal (stainless/non or low alloy)
•2)Single pass or multiple passes (non and low
alloyed steels only)
•2)Mechanical properties (impacts)
•3)Dedicated to one job or “universal “ product
in the workshop (optimisation)
50
SAW - 5. Consumables:Flux
• How to choose the proper flux:
•1)Base metal (stainless/non or low alloy):
•This will drive you to two different range of
products:
•Stainless :
P2000
•
P2000S
•
P7000 (Ni Base)
•Non & low alloyed : rest of the range
51
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
• 1)Single
pass / two run :
•What is it ?
•Two different kind of application
•High tech :2 passes (pipes)
•Low tech : one or 2 passes (sound weld at low cost)
52
SAW - 5. Consumables:Flux
Non & low alloyed steels, two run technique:
– 1)
Low tech
Main objective is sound welds at low cost
– Very often no or poor weld prep
• Oxy cutting + grinded edges
• Shear and grinded
Therefore we need an ACTIVE flux in
order to “clean the puddle
serie 7XX
53
SAW - 5. Consumables: Flux
•And In the 7XX family, how to choose it ?
•761 = Large weld puddle, low speed, resistance
to hot cracking
•780 = Because of is Medium Viscosity and high
freezing point It’s the best on roundabout
•782 = Because of is low viscosity and medium
freezing point it’s the best at high speed
54
SAW - 5. Consumables: Flux
•Q1) Therefore why don’t we use “7XX” fluxes everywhere ?
•A1)The Mn &Si will build up at each pass, therefore
multipass can drive to a very brittle weld.
•A2) Alloying depend on the voltage (non neutral fluxes)
55
SAW - 5. Consumables: Flux
Q2)“I
know some “single pass”
application with basic fluxes” ?
•A1) Definitely, but then the electrode chemistry
has to be adapted (Mo ,Mo Ti B or others).
•A2) Welding speed will be low and could probably
be optimized with an other type of fluxes.
56
SAW - 5. Consumables:Flux
Q3) Why not a fully basic flux for “high quality “ in single
or two run technique ?
57
SAW - 5. Consumables: Flux
Non & low alloyed steels, two run technique:
• 2) High Tech (pipes)
•Main objective is mechanical characteristics speed
and reliability
•Very clean and accurate weld prep
•Main concern will be:
•MICROSTRUCTURE
•(see the 9XX flux family)
58
SAW - 5. Consumables: Flux
Non & low alloyed steels:
• 3)Multipass :
We need a non active flux in order to control
the weld metal chemistry.
I.e alloys will be in the wire, tensile & yield will
depend on it.
In our LINCOLN range =
8XXX , P2XX, Mil 800H family
59
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
Basicity of the flux will drive the impact values
in multipass (but not the operability).
60
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
• 3)Multipass :
•860 : Very good operating characteristics, impact @ -20°c
•P230: Very good mechanical properties.Good operating
characteristics
•P240: Specific multipass flux.Very good mechanical ppt
Good slag removal if opening larger than 16mm
•8500: Very good mechanical properties and impacts even
in cap passes.Good operating characteristics
61
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
• 4)Multipass & / or single pass:
•We need a slightly active & neutral flux in
order to cover the all range =9XX family
But do not forget that if you can
cover everything, it’ a compromise.
9XX compromise impact of 8XX and
operability of 7XX
62
SAW - 5. Consumables: Flux
•Non & low alloyed steels:
• 4)Multipass & / or single pass:
•960 = Slow speed, large puddles, impact @ 20°C.
Plates thickness from 25mm and up
•980 = Impact @-0°C, good with contaminated plates.
Welding speed can be higher than 960 . Thin gauge
plates
•995N = Specific application with LNS 140TB
•P223 = Good impact and because of his slag freezing
point and viscisity very good in spiral pipe mills
63
SAW - 5. Consumables: Electrodes
Non & low alloyed steels:
•1) Single pass / two run :
•L61 : impact @0°C Consider it as a reference
(higher alloy if scale or rust, lower alloy if organic contamination
•Mo addition will improve impacts:
64
SAW - 5. Consumables: Electrodes
Non & low alloyed steels:
•
Single pass / two run :
•Addition of Mo +Ti B for optimum impacts (LNS 140TB)
65
SAW - 5. Consumables: Electrodes
•Non & low alloyed steels:
•2) Multipass :
•Electrodes composition will depend on the
requested mechanical characteristics.
•It will be defined according the requirement
: yield, tensile, impacts, PWHT or not …..
66
Submerged Arc Welding
1. Introduction
2. The SAW process
6. Reminder
3. Main variables effect
4. Welding defects
5. Consumables
6. Reminder
67
SAW - 6. Reminder
D=2,4 DC 25,0
SO 83mm
y = 0,0048x 1,2864
R2 = 0,998
20,0
y = 0,0047x 1,2552
R2 = 0,9989
kg / heure
15,0
y = 0,0072x 1,1468
R2 = 0,9979
SO 57mm
SO 25mm
10,0
5,0
0,0
300
350
400
450
500
Am ps
68
550
600
650
700
SAW - 6. Reminder
D=2,4 DC +
SO 83mm
18,0
16,0
y = 0,0008x 1,5154
R2 = 0,9997
SO 57mm
14,0
y = 0,0004x 1,6165
R2 = 0,9982
kg / heure
12,0
10,0
SO 25mm
y = 0,0036x 1,1896
R2 = 0,9915
8,0
6,0
4,0
2,0
0,0
300
350
400
450
500
550
Amps
69
600
650
700
SAW - 6. Reminder
D=3,2 DC +
25,0
SO 125mm
y = 0,001x 1,4841
R2 = 0,998
20,0
y = 0,0019x 1,3438
R2 = 1
kg / heure
15,0
y = 0,0011x 1,3751
R2 = 0,9977
10,0
SO 75mm
SO 25mm
5,0
0,0
300
350
400
450
500
550
600
650
Am ps
70
700
750
800
850
900
SAW - 6. Reminder
D=3,2 DC 30,0
SO 125mm
y = 0,0013x 1,4715
R2 = 0,9996
25,0
kg / heure
20,0
15,0
y = 0,0029x 1,3107
R2 = 0,9958
SO 75mm
y = 0,0057x 1,1708
R2 = 0,9999
SO 25mm
10,0
5,0
0,0
300
350
400
450
500
550
600
650
Am ps
71
700
750
800
850
900
SAW - 6. Reminder
D=4 DC +
25,0
SO 125mm
20,0
SO 75mm
kg / heure
15,0
SO 25mm
10,0
5,0
0,0
400
450
500
550
600
650
700
Am ps
72
750
800
850
900
950
1000
SAW - 6. Reminder
D=4 DC30,0
SO 125mm
25,0
SO 75mm
kg / heure
20,0
SO 25mm
15,0
10,0
5,0
0,0
400
450
500
550
600
650
700
Am ps
73
750
800
850
900
950
1000
SAW - 6. Reminder
SOUDAGE A L'ARC SUBMERGE
500
450
Vitesse de dévidage en cm /m n
400
350
Polynomial (2mm)
300
Polynomial (2,4mm)
250
Polynomial (3,2mm)
Polynomial (4mm)
200
Polynomial (4,76mm)
150
100
50
0
200,00
400,00
600,00
800,00
1000,00
Intensité en Am pères
74
1200,00
SAW - 6. Reminder
Basicity
of flux :
Basi. Index
–
–
–
–
Acid
<0,9
Neutral
0,9<BI<1,2
Basic
1,2<BI<2
Highly basic
<2
75
Melting range
1100°c /1300°c
1300°c/ 1500°c
>1500°c
>1500°c
