Transcript Перенос электродного металла при сварке

MIG/MAG spray and streaming metal
transfer modes
- Welding conditions for these metal transfer
modes
- Their advantages and limitations
NTUU “KPI”, UFU, PWI TQC
E1815-01
Ponomarev V., Slivinsky A.
Transfer modes versus welding
current and arc voltage
Ua
CO2, or argon
based mixtures
Argon based mixtures
Transition
current
Streaming rotating
Globular
Streaming
Spray
MIG-Pulsed
Short-circuiting
NTUU “KPI”, UFU, PWI TQC
E1815-01
Iw
Ponomarev V., Slivinsky A.
Globular – spray transfer transition
Droplet diameter
180 A
Iw < Itr (190 А)
AWS ER70S-6
1.0 mm; Ar2%O2
Rate of droplet transfer
Transition current
250 A
211 A
Iw > Itr
Current
Iw
Iw
Iw
Femr
Femz
NTUU “KPI”, UFU, PWI TQC
Femz
E1815-01
Ponomarev V., Slivinsky A.
Transition current for different electrode
materials and diameters as well as for
different shielding mixtures
Electrode wire material
Electrode wire
diameter, mm
Low-carbon steel
0,8
1,0
1,2
1,6
Low-carbon steel
0,8
1,0
1,2
1,6
Stainless steel
0,9
1,0
1,2
1,6
Aluminium
0,8
1,0
1,2
1,6
NTUU “KPI”, UFU, PWI TQC
E1815-01
Shielding mixture
Transition current,
А
95%Ar + 5%CO2
140
180
240
280
80%Ar + 20%CO2
160
200
275
280
98%Ar + 2%O2
170
170
225
285
Argon
90 - 95
100
120
170 - 180
Ponomarev V., Slivinsky A.
Examples of spray metal transfer
 1 mm; Ar+5%O2; 197 А
 1 mm; Ar+2%O2; 211 А
The welding current slightly
exceeds
the
transition
current level
The droplets are transferred in line with electrode
rather than along the shortest path between the
electrode and workpiece that is typical for this
mode of the metal transfer.
NTUU “KPI”, UFU, PWI TQC
E1815-01
Ponomarev V., Slivinsky A.
The spray transfer can be experienced
at different arc lengths
Melting rate:
8.1 m/min
8.8 m/min
9.5 m/min
The shorter is the arc, the longer becomes the electrode extension (provided the
contact tube – to - work distance is kept changeless) and, as a result, the electrode
gets more intensive preheating by the current and therefore its melting rate rises
(low-carbon wire of 1 mm and 211 А for all three tests).
NTUU “KPI”, UFU, PWI TQC
E1815-01
Ponomarev V., Slivinsky A.
Welding conditions and application sphere
of the spray and streaming transfers
Welding conditions for spray and streaming
transfers:
1. High arc voltage and welding current;
2. Shielding: argon based mixtures.
MIG/MAG spray and streaming transfer
application is restricted to welding only in the
flat position because, in spite of the fact that
all droplets are getting into the weld pool, the
pool itself is too large to be properly
controlled when welding in the vertical or
overhead position.
NTUU “KPI”, UFU, PWI TQC
E1815-01
Ponomarev V., Slivinsky A.