welding of aluminium

1. WELDING OF ALUMINIUM &
TITANIUM
T. K. MITRA
BHEL, TRICHY

2. WELDING OF ALUMINIUM

3. Important Properties of Aluminium
 Pure Al. - Low strength :70-90 MPa.
 Al. Alloys - Mod. Strength : 90-500 MPa.
 Light weight : D  2.7 g/cc.
 High strength to weight ratio.
 Good corrosion resistance.
 Ductile.
 Good formability.
 Low temperature toughness.
 High electrical conductivity.
 High thermal conductivity.

4. Applications
 Transportation
 Aerospace & Defence
 Building & Architecture
 Packaging, Containers, Cryo-vessels
 Electrical cables & Bus-bars
 Household & consumer durables
 Machinery
automobile,
railway, marine
Aircraft, launch vehicles for
space & missiles, naval
ships, speedboats

5. Consumption of Aluminium
World Consumption of Aluminum,(1992)
Transport
24%
Building &
Construction 23%
Electricals
9%
Consumer
Durables 5%
Machinery
6%
miscellaneous
12%
Container & Packaging
21%
Consumption of Aluminiumin India,(1992)
Electricals
39%
Consumer
Durables 15%
Machinery 10%
Miscellaneous
5%
Container &
Packaging 8%
Transport 17% Bidg. & Cons.6%

6. Aluminium
Vessels
Application in Industry

7. Aluminium in
road transport
Application in Industry

8. Aluminium in
transport
industry
Application in Industry

9. Application in Aerospace Industry.

10. AA Series IS Series
 1XXX (99% Al) :1060 19800
 2XXX (Al-Cu) :2219 24345 (HT)
 3XXX (Al-Mn) :3003 31000
 4XXX (Al-Si) :4043 43000
 5XXX (Al-Mg) :5083 54300
 6XXX (Al-Mg-Si) :6061 65032 (HT)
 7XXX (Al-Zn) :7005 74530 (HT)
 8XXX (New Alloys) :8090
Aluminium Alloy Classification

11. Cast aluminium alloy groups
Alloy group Series designation
Aluminium, 99.00% min purity 1XX.X
Aluminium-copper 2XX.X
Aluminium-silicon-copper or
aluminium-silicon-magnesium
3XX.X
Aluminium-silicon 4XX.X
Aluminium-magnesium 5XX.X
Aluminium-zinc 7XX.X
Aluminium-tin 8XX.X
Other alloy systems 9XX.X

12. Aluminium Alloy Temper Designations
F As fabricated
O As annealed
Hxx Strain-hardened with combinations of
annealing, stabilisation, ¼ hard, ½
hard, ¾ hard, full hard etc.
W Solution heat-treated
T Thermally treated to produce stable
tempers other than F, O, or H
T1-T10 Different combinations of thermal
treatment with or without cold work,
stabilisation, ageing etc.

13. Problems in Welding Aluminium
High affinity for oxygen.
High thermal conductivity.
Softening in HAZ of age hardened alloys.
Susceptibility to cracking.

14. Problems in Welding Aluminium
High affinity for oxygen results in quick
formation of Tenacious Al. Oxide skin.
 Melting temp.of Al. oxide is high (2050C)
 3 times of Aluminium ( 650C)
 Al. Oxide promotes lack of bonding.
 In-process cleaning of oxide is achieved by
cathodic cleaning in TIG and MIG welding.
 (Meticulous cleaning of groove before
welding required)

15. Aluminium metal melts.
Aluminium oxide skin
remains unmelted.
Al. oxide skin
Mp.2050°C
Aluminium
Mp.650°C
Aluminium oxide in
weld-pool impedes
bonding

16. Oxide cleaning in electrode +ve half cycle,
Penetration in electrode --ve half cycles
in AC TIG welding

17. Problems in Welding Aluminium
Softening in HAZ in Age Hardened alloy.
Reasons:
 Resolutionizing of age hardening
precipitates.
 Overageing of precipitates.
Resulting in:
Joint Efficiency in as welded condition
60-70% of age hardened alloy.

18. Problems in Welding Aluminium
Softening in HAZ in age hardened alloy.
Resolutioned B.M
Over aged B.M
Unaffected
B.M
Weld

19. Softening in HAZ of Age - hardened Aluminium Alloy

20. Problems in Welding Aluminium
Basically Hot Cracks :
 Solidification cracks in weld.
 Liquation cracks in weld & HAZ (PMZ).
Cracking in Aluminium
alloys

21. Cracking in Aluminium Alloys
1. Select an weldable alloy, which is
less susceptible to cracking.
2. Select a filler alloy to avoid crack
sensitive weld metal composition.
Filler alloy should have a lower
freezing range than base metal.
(Composition and freezing range are
important factors).
3. Use less heat-input.
4. Avoid rigid clamping / fixtures.

22. Cracking in Aluminium alloys
Crack sensitive Base Metals usually have wide
solidification range.
(Large difference between Solidus and Liquidus
temperatures is caused by minor alloy additions made to
increase strength.
Alloy Composi-
tion
Solidus
ºC
Liquidus
ºC
Weld
Rating
7075 Zn :5.6
Mg : 2.5
Cu :1.6
477 635 C
7079 Zn :4.3
Mg : 3.3
Cu :0.6
482 638 C
7178 Zn :6.8
Mg :2.8
Cu :2.0
477 629 C
Strength
572 MPa T6
538 MPaT6
607 MPa T6

23. 6061 pipe welding (Root run )
(A) Without filler addition (B) With filler addition

24. Selection of filler metal for lesser risk
of cracking.
Fig.5. Crack sensitivity of some base metal / filler metal combinations. Source : ASM Metals Handbook, Ref.1.

25. Filler Metals for Welding of Aluminium
Some important filler metals:
ER1100.
ER2319.
ER4043 (Al-5%Si), 4047, 4045.
ER5356(Al-5%Mg), 5183, 5556.
Available in spools of wire,
dia 1.2mm and 1.6mm(MIG, Mech. TIG).
Dia 2.0mm, 2.4mm, 3.2mm, 4.0mm in straight
lengths for TIG welding.
Similar
classification
as Base
Metals

26. Chemical Composition of Wrought Aluminium Filler Metals
Elements, wt% Other
Elements
Filler
Alloy
Si Fe Cu Mn Mg Cr Zn Ti Each Total
Al
1100 Note b Note b 0.05 -
0.20
0.05 --- --- 0.10 --- 0.05
C
0.15 99.0
min
2319 0.20 0.03 5.8 -
6.8
0.20-
0.40
0.02 --- 0.10 0.10 -
0.20
0.05
C
0.15 Rem
4043 4.5 -
6.0
0.80 0.30 0.05 0.05 --- 0.10 0.20 0.05
C
0.15 Rem
4047 11.0 -
13.0
0.80 0.30 0.15 0.10 --- 0.20 --- 0.05
C
0.15 Rem
4145 9.3 -
10.70
0.80 3.3 -
4.7
0.15 0.15 0.15 0.20 --- 0.05
C
0.15 Rem
5183 0.40 0.40 0.10 0.50 -
1.0
4.3 -
5.2
0.05 -
0.25
0.25 0.15 0.05
C
0.15 Rem
5356 0.25 0.40 0.10 0.05 -
0.20
4.5 -
5.5
0.05 -
0.20
0.10 0.06 -
0.20
0.05
C
0.15 Rem
5554 0.25 0.40 0.10 0.50 -
1.0
2.4 -
3.0
0.05 -
0.20
0.25 0.05 -
0.20
0.05
C
0.15 Rem
5556 0.25 0.40 0.10 0.50 -
1.0
4.7 -
5.5
0.05 -
0.20
0.25 0.05 -
0.20
0.05
C
0.15 Rem
5654 Note g Note g 0.05 0.01 3.1 -
3.9
0.15 -
0.35
0.20 0.05 -
0.15
0.05
C
0.15 Rem

27. Filler Metals for Welding of Aluminium
Criterion for selection of filler metal:
1. Base metal composition.
2. Ease of welding / Cracking tendencies.
3. Strength and ductility of the weld.
4. Corrosion resistance.
5. Colour match between weld and base metal
after anodising.

28. Welding Processes for Aluminium
Most widely used processes :
 AC TIG
 MIG (conventional)
Other Special processes :
DCSP TIG
Pulsed MIG
Plasma Arc Welding (key hole mode)
Electron Beam Welding

29. AC TIG Welding of Aluminium
 Most widely used method to weld Al.
 Good oxide cleaning by the arc.
 Average penetration.
 Suitable for manual welding in all positions
and mechanised welding.
 Use pure or zirconiated tungsten
electrodes with hemispherical tip.

30. Oxide cleaning in electrode +ve half cycle
Penetration in electrode --ve half cycles
in AC TIG welding.

31. Sine Wave In AC TIG Welding
AC Freq.50 Hz.
EN/EP 50/50

32. Wave balance (EN/EP ) & AC frequency Variables
In Square Wave AC TIG Welding

33. Requirements:
 Short arc length & Helium shielding.
 Mechanised welding, faster speed.
Advantages:
 Weld and HAZ width are narrower.
 Less softening of HAZ.
 Square butt joints produced in single
pass.
DCSP TIG Welding of Aluminium

34. DCSP TIG Weld, 7.4mm Sq. butt
Single Pass, 350mm /min.
Top Bead
Root Penetration Bead
DCSP TIG, 7.4mm 2219 alloy
Square butt joint

35. TIG Weld Bead Profile in Al. Alloy.
DCSP TIG weld
7.4mm thick
Al. Alloy
AC TIG weld
4mm thick
Al. Alloy

36. MIG Welding of Aluminium requires
“Spray” type of metal transfer.
Process Options :
 Conventional MIG (Un-pulsed)
 Pulsed MIG.
MIG Welding of Aluminium

37. Spray type of metal transfer
 Has a typical fine arc
column with pointed wire tip.
 Very small drops are formed
and detached at rate of
hundreds per sec.
 Drops are accelerated
axially across the arc gap.
(helps in overhead welding).

38. High current required for spray transfer.
1.6mm dia.wire :180 amperes
1.2mm dia.wire :135 amperes
Resultant high arc force cuts thro’ thin
metal.
High wire feed rate leads to high deposition
and weld pool flooding.
PROBLEMS IN CONVENTIONAL
MIG WELDING

39. Welding current is pulsed between a
high peak current (in the spray region)
and a low background current (below
spray region) in a given pulsing
frequency. Average current remains
below spray region, but with spray
transfer.
Pulsed MIG Welding

40. Parameters in Pulsed MIG Welding:
1. Peak Current, Ip (metal transfer)
2. Background Current, Ib (No metal transfer)
3. Time at Peak Current, Tp
4. Time at Background Current, Tb
5. Wire Feed Rate.
Transfer rate of ONE drop per pulse is ideal.
Pulsed MIG Welding

41. Pulsed MIG Wave form

42. Bead Appearance in Butt Joints
AA 5083 alloy, 3.15mm thick.
Pulsed MIG
Conv. MIG
AC TIG

43. Shielding Gases for TIG & MIG welding:
 Argon (AC TIG, MIG).
 Helium (DC TIG, MIG).
 Argon-Helium mixture.
(80/20 – AC TIG), (50/50 - MIG)
 Control of impurity important for high
quality welds.
 Moisture, oxygen, nitrogen and hydro-
carbons are impurities.
Welding of Aluminium

44. Welding Techniques:
1. Fore Hand.
2. Vertical up.
3. 6’O clock to 12’O clock in 5G
positional welding.
4. Stringer bead preferred. Avoid
wide weaving.
5. Use min. or no preheat.
Preheat <200ºC.
Welding of Aluminium

45. Always Forehand
and Vertical up in
Welding Aluminium
Direction of welding

46. Joint design in
Aluminium welding

47. Joint design for welding pipe from outside

48. Joint geometries for arc welding aluminium in horizontal position.

49. Welding Aluminium
Defects in Aluminium welds :
1. Pores
2. Lack of fusion/bonding.
Remedy: Adjust parameter (heat input),
Improve cleanliness.
3. Cracks
Remedy: Reduce heat input,
Select proper B.M
& filler metal combination.

50. Defects in Aluminium welds
Pores :
Caused by dissolution of
hydrogen in weld metal.
Causes : Impurity from gas,
filler metal, base metal
and environment.
Remedy:
Keep B.M., F.M. clean.
Use argon with high purity
(Controlled moisture content).

51. Welding of Titanium

52. TITANIUM
& its
ALLOYS
Silver coloured, reactive,
exotic metal.
High specific strength,
modulus & toughness.
Exceptional corrosion and
fatigue resistance.
High temperature
serviceability.
Lighter than steel
(D  4.5g /cc).

53.  Ti oxidises rapidly at elevated temperature.
 Ti dissolves O2, N2, H2 interstitially at high
temperature encountered in welding causing
embrittlement.
 Requires additional shielding of hot solidified weld
bead till cooled to 350ºC.
 Fusion welding with steel or most other metals not
feasible.
 Expensive metal
TITANIUM : Basic Characteristics

54. APPLICATIONS:
• Aerospace
• Defence
• Marine
• Chemical & petrochemical Process
Equipment
• Surgical Implants
• Sports Equipment
TITANIUM

55. Applications in TITANIUM

56. Nominal Composition, wt% Impurity limits (max.), wt%
Mechanical Properties
At Room Temperature
Designation
Al Sn Zr Mo Others N C H Fe O UTS (MPa) YS %E
Unalloyed Grades
ASTM Gr.1 --- --- --- --- --- 0.03 0.10 0.015 0.20 0.18 262 A 186 30
ASTM Gr.2 --- --- --- --- --- 0.03 0.10 0.015 0.30 0.25 414 A 310 28
ASTM Gr.3 --- --- --- --- --- 0.05 0.10 0.015 0.30 0.35 517 A 414 25
ASTM Gr.4 --- --- --- --- --- 0.05 0.10 0.015 0.50 0.40 621 A 517 20
ASTM Gr.7 --- --- --- --- 0.2Pd 0.03 0.10 0.015 0.30 0.25 427 A 317 27
ASTM Gr.11 --- --- --- --- 0.12-0.25Pd 0.03 0.10 0.015 0.20 0.18
ASTM Gr.12 --- --- --- 0.3 0.6-0.9 Ni 0.03 0.10 0.015 0.30 0.25 510 A 414 33
Alpha and Near-Alpha Alloys
Ti-5Al-2.5Sn 5 2.5 --- --- --- 0.05 0.08 0.02 0.50 0.20 862 A 827 15
Ti-5Al-
2.5Sn-ELI
5 2.5 --- --- --- 0.07 0.08 0.0125 0.25 0.12
Ti-8Al-1Mo-
1V
8 --- --- 1 1 V 0.05 0.08 0.015 0.30 0.12 924 A 855 14
Ti-6Al-2Sn-
4Zr-2Mo
6 2 4 2 --- 0.05 0.05 0.0125 0.25 0.15 986 A 938 13
TITANIUM ALLOYS : ASTM GRADES
TITANIUM ALLOYS : RUSSIAN GRADES
PT – 1M : C < 0.07, O < 0.12, H < 0.006, N < 0.04,
Fe < 0.20, Al: 0.2- 0.7, Zr < 0.30, Si < 0.10, Ti –Bal.
PT – 7M : C < 0.10, O < 0.15, H < 0.006, N < 0.04, Fe < 0.25
Al :1.8 - 2.5, Zr : 2.0 - 3.0, Si < 0.12, Ti – Bal .

57. Titanium Alloys : ASTM Grades
Titanium Alloys
Nominal Composition, wt% Impurity limits (max.), wt%
Mechanical Properties
At Room Temperature
Designation
Al Sn Zr Mo Others N C H Fe O UTS (MPa) YS %E
Alpha-beta Alloys
Ti-6Al-4V 6.0 --- --- --- 4.0 V 0.05 0.10 0.0125 0.30 0.20 931 A
1117 STA
896
1034
15
12
Ti-6Al-4V
ELI
6.0 --- --- --- 4.0 V 0.05 0.08 0.0125 0.25 0.13
Ti-3Al-2.5V 3.0 --- --- --- 2.5 V 0.015 0.05 0.015 0.30 0.12 717 A 586 22
Beta Alloys
Ti-13V-
11Cr-3Al
3.0 --- --- --- 11Cr, 13 V 0.05 0.05 0.025 0.35 0.17 910 A
1207 STA
869
1138
10
4
Ti-8Mo-8V-
2Fe-3Al
3.0 --- --- 8.0 8.0 V 0.05 0.05 0.015 2.5 0.17 883 A
1241 STA
848
1207
12
8
Ti-11.5Mo-
6Zr-4.5Sn
(BetaIII)
--- 4.5 6.0 11.5 --- 0.05 0.10 0.020 0.35 0.18 841 A
1524 STA
793
1427
15
6
A: Annealed. STA : Solution treated & aged.
PT – 3B : C < 0.10, O < 0.15, H < 0.006, N < 0.04, Fe < 0.25
Al :3.5-5.0, V :1.2 - 2.5, Zr < 0.30, Si < 0.12, Ti – BAL
Titanium Alloys : Russian Grades

58. FUSION WELDING:
TIG Welding
Plasma Arc Welding
Electron Beam Welding.
NON-FUSION SOLID PHASE PROCESS:
DIFFUSION BONDING
SUPER-PLASTIC FORMING /
DIFFUSION BONDING (SPF/DB)
FRICTION WELDING
EXPLOSIVE BONDING
Joining Processes for Titanium

59.  WELDING IN INERT ATMOSPHERE
CHAMBERS
(FLOW PURGED & VACUUM PURGED).
 OPEN AIR WELDING WITH AUX.
SHIELDING.
TIG Welding of Titanium

60. TIG Welding of Titanium
WELDING IN INERT ATMOSPHERE CHAMBER :
Welding in Flow
purged chamber
Welding in Vacuum
purged chamber

61. TIG Welding Of Titanium
Primary shielding Thro’ TIG torch for
weld-pool
Secondary shielding Thro’ Trailing shield
for solid weld & HAZ
Back side shielding Thro’ Grooved
backing bar for root
bead shielding
Open air welding with auxiliary
shielding:

62. Open Air TIG Welding of Titanium
trailing shield
TIG welding of
titanium pipe with
trailing shield
TIG welding of
titanium plate with
trailing shield and
grooved backing bar

63. Contamination leads to
cracking, porosity, embrittlement
Contamination caused by:
 Ineffective primary shielding
 Ineffective trailing shield
 Contaminated shielding gas
 Contaminated base metal & filler metal
Contamination in Titanium Weld

64. Cleanliness – cleanliness & cleanliness
 High purity shielding gas (Ar)
 Good shielding – Primary, Trailing, Root
 Clean base metal,filler metal & work station
(i) degreasing, pickling,
(ii) high surface finish of groove & Filler
(iii) protect joint area after m/c till welding
(iv) dust free Clean Room environment,
(v) clean tools & welding accessories,
(vi) welding personnel with clean white gloves apron.
Countering Contamination

65. Contaminated surface colouration
Colour Shielding Efficiency Effect
Shining
Silver
Good effective trailing
shield
No embrittlement
Golden Slight contamination Contamination at about
540ºC. No serious effect.
Can be brushed off.
Largely acceptable.
Light Blue Inadequate shielding.
Slightly more
contamination.
Acceptable depending on
application.
Deep Blue Exposed at high
temperature after
solidification.
Embrittlement of weld.
Remove Weld bead.
Grey / White
Flaky
Exposed at melting or
close to melting
temperature.
Highly brittle. Not
acceptable.
Contamination in Titanium Weld

66. Contamination
colours in
Titanium
welds.
Clean weld
in Titanium

67. Brittleness by contamination
Clean silver
coloured bead
Effective shielding.
Oxygen content in the weld : 0.074%
T.S. : 460 MPa.
Hardness : 188-193 HV10

68. Brittleness by contamination
Light golden / straw
coloured bead
Slightly disturbed trailing shielding.
Oxygen content in the weld : 0.101%
T.S. : 485 MPa.
Hardness : 195-205 HV10

69. Brittleness by contamination
White flaky bead
Contaminated primary shielding (Ar+O2).
Trailing shield inadequate.
Oxygen content in the weld : 0.410%
T.S. : 580 MPa.
Hardness : 400-413 HV10
Cracked in bend test.

70. Welding of pipe branch connections

71. TIG Welding of pipe branch connections
Ti pipe
Ø100x6mm
Branch pipes,
Ø21-40mm,
Th.:2.1-4.5mm
Shielding :
Inside
pipes by
purging.
Shielding :
Outside by
trailing shield