Laser Welding of Thick Structural Steels
Hans Engström, Jan Flinkfeldt, Klas Nilsson Luleå University of Technology
Tony Nilsson, SSAB Tunnplåt AB Anders Skirfors, SSAB Oxelösund AB
Marcus Miller, Volvo Articulated Haulers AB
Presentation
• Introduction
• Experimental
• Results
– Properties of welded material – Weld defects
– Process windows – Fatigue testing
• Conclusion
Introduction
Benefits of Laser Welding
• High Welding Speeds
• Low distortion
• New design opportunities
Laser equipment used
Laser I II
Power [kW] 12 17
Focal length [mm] 270 300
Beam diameter in focus [mm] 0,5 0,8 Double focusing optics 0,6 mm between focal spots
Shielding gas He He
Shielding gas arrangement ”Ring nozzle”
1Coaxial nozzle + plasma gas Workstation Moving laser beam, fixed work
table
Fixed laser beam, x/y-table
Experimental set-up
Materials
High Strength Cold Forming Steel - DOMEX
High Strength Structural Steel - WELDOX
Wear Resistant Steel - HARDOX
Steel grade R
p0,2MPa
R
mMPa
A
5(A
80)
%
Charpy-V J/cm
2/C Domex 355 XP 10 mm 376 462 38 (41) 344 / -20
Domex 460 MC 8 mm 523 616 19 (19) 223 / -20 220 / -40 Domex 600 MC 8 mm 674 749 22 (23) 103 / -20 80 / -40 Domex 390 XP 12 mm 410 507 28 (32) 363 / -20 295 / -40
Materials
Steel grade T mm
Rp 0,2 MPa
Rm MPa
A5
%
Charpy V J/ °C
Hardness HB
CE
IIW3WELDOX 960 10 1027 1073 13 35 / -40
1- 0,55
HARDOX 400 10 -- -- -- -- 408 0,37
HARDOX 400 15 989
41250
412
480 / -40
2, 4400
40,38
Joint types and preparation
•I-joint, (butt weld) autogenous, laser cut or milled edges
•I-joint (butt weld) filler material 1 , laser cut or milled edges
•V-joint filler material 1
•Edge joint 90°
•Edge joint 45º
DOMEX 390XP 12 mm DOMEX 355XP 10 mm
Cutting machine 1 above; 2 below
1.Esab OK Autrod 12.51, 12.64
Results DOMEX steels
Domex 355XP 10 mm
0 100 200 300 400
0 2 4 6 8 10 12 14 16
Distance (mm)
Vickers
Hv5
Domex 600 MC 8,0 mm
0 100 200 300 400
0 2 4 6 8 10 12 14 16
Distance (mm)
Vickers
Hv5
Results DOMEX
Strength OK Fracture in base material
Elongation OK Guaranteed values for base material achieved V-bending OK (Punch diameter=4xt)
Toughness OK Demand normally 50J/cm 2 at -20 º (base material)
Weld metal 355XP 390XP 460MC 600MC
8 mm -60º (-40º ?) -60º
10 mm -60º
12 mm -60º
Results WELDOX and HARDOX
200 250 300 350 400 450
0 2 4 6 8 10 12 14 16 18
Distance (mm)
Hardness (HV5)
WELDOX 960 10 mm HARDOX 400 10 mm
Results WELDOX and HARDOX
Material T [mm] ∆t8/5
[s]
RP 0,2
[Mpa] Rm
[MPa] A50
[%] Fracture
position Charpy V toughness
5–40°C [J]
WM
3/HAZ
4WELDOX 960 10 6 1036 1088 24 BM
218/18
10 2 1032 1086 23 BM 15/15 HARDOX 400 10 5 1032 1058 4 HAZ 20/22
10 2 1108 1213 6 HAZ 30/15
10 1 1114 1230 7 HAZ 23/20
15 5 1011 1108 8 HAZ 30/27
Welding defects
2000x 400x
40x
1 mm
Process Windows
Power
[kW] Welding speed
[mm/min]
11 500 700 900 1100 1300 1400 1500 1600 14 800 1000 1200 1400 1600 1800 2000 2200 17 1000 1200 1500 1800 2000 2200 2400 2600
DOMEX 390 XP, 12 mm bead-on-plate
Process windows
11 14 17 kW
1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6 m/min DOMEX 390 XP, 10 mm, lasercut
Autogenous
Not approved Approved Approved He/4% O2
1,2 1,4 1,6 1,8 2,0 2,2 2,4 11
14 17 kW
DOMEX 390 XP, 10 mm, milled Autogen
not approved approved
approved, He/4%O2
DOMEX 390 XP 10 mm
Laser cut
Milled
Autogenous
Process Windows
not approved
11 14 17 kW
1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 m/min DOMEX 390 XP, 10 mm, lasercut
Filler material
DOMEX 390XP 10 mm Filler material
Laser cut
Milled
1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6 11
14 17 kW
m/min DOMEX 355 MC, 10 mm, milled,
Filler material
not approved approved
Process windows
11 14 17 kW
0,8 1,0 1,2 1,4 1,6 1,8 2,0 m/min DOMEX 390 XP, 12 mm, lasercut
Autogenous
= not approved
= not approved He/4%O2
= approved
= approved He/4%O2
11 14 17 kW
0,8 1,0 1,2 1,4 1,6 1,8 2,0 m/min DOMEX 390 XP,12 mm, milled
Autogenous
not approved not approved He/4%O2
approved approved He/4%O2
DOMEX 390XP, 12 mm
11 14 17 kW
0,8 1,0 1,2 1, 1,6 1,8 2,0 m/min DOMEX 390 XP, 12 mm, lasercut
Filler material
not approved, welding speed/wire speed=1:1 not approved, welding speed/wire speed=1:2 approved, welding speed/wire speed=1:1
approved, welding speed/wire speed=1:2
Autogenous
Laser cut
Milled Filler material
Bead-on-plate
Process windows
m/min Hardox 400, 10 mm laser cut
Autogenous
not approved approved
1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6 11
14 17 kW
Weld speed/wire speed 1:1
11 14 17 kW
m/min Hardox 400, 10 mm, laser cut
Filler material
not approved approved
1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6
HARDOX 400, 10 mm
Autogenous Filler material
Laser cut
Weld Geometry
Thickness
[mm] Focal point position
[mm] Weld
geomertry Welding Speed [m/min]
Weld quality
10 +5 1,5 Approved
1,8 Approved
-5 1,2 Approved
± 0
12 -5 1,5 Approved
± 0 1,5 Not approved
+5 Not full penetration
Torsion Fatigue
150 120
Laser- stråle
10 1000
100000 1000000 10000000
No of cycles to failure, Nf
Stress range Mpa
MAG
Laser
Laser 2