traidia@ensta-paristech.fr 1

A Transient Unified Model of Arc Weld Pool Couplings during Spot

GTA Welding

COMSOL Conference, Boston 2010

A. TRAIDIA, and F. Roger

ENSTA-Paristech & AREVA NP, FRANCE

traidia@ensta-paristech.fr 2

Introduction

Gas Tungsten Arc Welding – Tungsten Inert Gas

A highly coupled multiphysics problem

traidia@ensta-paristech.fr 3

Numerical modeling of pulsed GTA welding

State of art – Towards a unified formulation

Hsu et al (1982, …)

Gonzalez et al (1993, 1998, 2005, …)

Lowke, Tanaka et al

(1992, 1997, …, 2010)

Plasma

Plasma

+

Cooled copper anode

(No weld pool)

Cathode

+

Plasma

+

Stainless steel anode

(weld pool)

traidia@ensta-paristech.fr 4

Numerical modeling of pulsed GTA welding

Toward a unified model Mathematical formulation

Inside the cathode, plasma, and anode

Plasma-cathode interface

Plasma-anode interface

Free surfaces of the weld pool

Main boundary conditions

4( ) ( ) i i e c Bcathode plasmak T n k T n jV j T

4( ) ( ) a Banode plasmak T n k T n j n T

( )a L

v s Tf

n T s

0

01

ln 11

exp

sg s s s

s

g

Ka HA R Ka

T Ka T

HK T k

R T

traidia@ensta-paristech.fr 5

Numerical modeling of pulsed GTA welding

Application to pulsed current

welding 80/160 A

1 Hz

α 60°

Arc length 3 mm

Heating time: 15 s

304 L with 290 ppm sulfur

Pure argon

Tu

ng

ste

n

Imax

Imin

Time(s)

Welding current (A)

traidia@ensta-paristech.fr 6

Numerical modeling of pulsed GTA welding

Results Application to pulsed current

welding

80/160 A- 1 Hz

α 60°- h 3 mm

traidia@ensta-paristech.fr 7

Numerical modeling of GTA welding

80/160 A- 1 Hz

α 60°- h 3 mm Results Application to pulsed current

welding

Details about the weld pool evolution in: A. Traidia, F. Roger, E. Guyot. “Optimal parameters for pulsed gas

tungsten arc welding in partially and fully penetrated weld pools”. IJTS 2010.

traidia@ensta-paristech.fr 8

Numerical modeling of pulsed GTA welding

80/160 A- 1 Hz

α 60°- h 3 mm

Fully penetrated weld pool

Solutions at t=4.5 s and t=5 s Free surfaces shape at different times

Results Application to pulsed current

welding

traidia@ensta-paristech.fr 9

Experimental validation

Experimental procedure

Observation of the weld pool using an IR camera

traidia@ensta-paristech.fr 10

Experimental validation

Validation

Experimenal width of the weld pool Matlab image processing algorithm

traidia@ensta-paristech.fr 11

Experimental validation

Validation

Experiments/Calculations

Accumulation

of metal

vapors in the

arc plasma

traidia@ensta-paristech.fr 12

Thank you for your attention,

Any questions ?

traidia@ensta-paristech.fr 14

Numerical modeling of GTA welding

Appendix A

Cathode (-)

Anode (+)

Plasma

Joule effect

Conduction to

the cathode

Thermoionic

emission

Ions absorption

Conduction to

the anode

Radiation

Joule effect

Air convection

Air convection

Radiation Conduction from

the plasma

Electrons

absorption

Radiation

Plasma physics

traidia@ensta-paristech.fr 15

Numerical modeling of pulsed GTA welding

80/160 A- 1 Hz

α 60°- h 3 mm Appendix B Application to pulsed current

welding

Weld pool dimensions for a pulsed current welding and its constant mean current