This document summarizes the weldability of nickel and titanium alloys and selection of welding processes. It discusses that nickel alloys like monel and inconel have good weldability by TIG, MIG, and SMAW processes. Preheating is generally not required but post weld heat treatment may be needed. Titanium alloys including pure titanium, alpha, alpha-beta, and beta alloys can be welded by TIG and electron beam processes. Porosity is a major issue in titanium welds due to gas entrapment during solidification. Stress relief heat treatment may be required after welding of some titanium alloys.

1. WELDABILITY OF Ni & Ti ALLOYS
AND
SELECTION OF WELDING
PROCESS & PROCEDURE
Submitted by,
saroja.s
(ME , welding technology)
GCE,SALEM

2.  Nickel like copper, its FCC structure at all
temperature .
 Good corrosion resistance. its used food
processing plants ,chemical container and
other similar application.
 Nickel is used as alloying element to improve
mechanic properties.
 Resistant of oxidation in high temperature.
 Nickel melting point is 1453˚C.
 Nieq=%Ni+30*%C+0.5*%Mn.

6. Solid solution alloy:
 Ni-Cu=alloy 30-45%Cu its monel.
 Ni-Cr=16-20%Cr its nichrome.
 Ni-Fe-Cr=20-25%Ni,13-22%Cr,Fe-bal its INCONEL
 Ni-Mo=16-28%Mo,less % of Cr&Ni.
Precipitation hardening:
 Ni-cu.66.5%Ni,29.5%Cu monel
 Ni-Cr.76%Ni,19.5%Cr nichrome
 Ni-Fe-Cr. 73%Ni,15.5%Cr,7%Fe inconel

7. Solid Solution
Nickel - Copper
• Resistance to Sea Water
• Naval Application, Chlorination Plants, Water meter parts, pump
shafts, feed water heaters
Nickel-Chromium
• Corrosion Resistance at Elevated Temp
• Furnace muffles, heat treating equipment, nuclear steam tubing, heat
exchangers, aircraft engine components
Nickel-Iron-Chromium
• High Temp Strength, Resistance to Oxidation
• Heat exchangers, carburizing fixtures, pickling tank heaters, spent
nuclear fuel element recovery, hydrofluoric acid production
Nickel-Molybdenum
• Low temp corrosion resistance, some acids
• Cryogenic Service

8. Precipitation-hardening
Nickel-Copper Alloys
• Resistant to Sea Water, Chlorine
• Pump shafts, impellers, oil well drill collars, electronic components,
springs
•Sensitive to strain age cracking
Nickel-Chromium
• Good high temp oxidation
• Gas turbine components
Nickel-Iron-Chromium
• Forging applications

9. Phase diagram of Ni-Cu

13. MONEL AND INCONEL:
WELDING PROCESS:TIG,MIG,SMAW,elactron beam
PREHEAT: No
POST WELD: Necessary to avoid intergranular corrosion
REMARK: Good weldability
A=RECOMMENDED;C=POSSIBLY USABLE BUT NOT POPULAR
NO=NOT RECOMMENDED
proces
s
SMA
W
TIG PLAS
MA
SAW MIG FCAW
NICKEL A A A C A NO
INCON
EL
A A A NO A NO
MONEL A A A C A NO

14. GMAW techniques
 GMAW uses solid wires use for filler metal.
 The recommended polarity is DCEP with, normally,
constant-potential power sources.
 With a solid wire, the dominant mode of metal
transfer is spray transfer, but short circuiting and
globular welding are also widely employed
depending on the welding position and joint
thickness.
 For shielding the weld zone, shielding normally
use argon or argon mixed with helium.

17.  Ni & its alloy are used in coin.
 Chemical plant , heat exchanger , reaction
furnace are used
 Turbine blades,bumper , cutting tool
Imperfection:
Porosity
Lack of inter run fusion
Weld metal solidification cracking
Precaution:
Post weld heat treatment

18.  Pure Ti low tensile strength but excellent
ductility
 High strength to weight ratio compare to Al
 Suitable alloys added properties can
increased
 Above 650℃ reduce oxidation resistance
 Low thermal expansion & thermal
conductivity.
 Room temp , HCS called alpha phase. above
the 883℃ beta phase in BCC.
 Melting point is 1670 ℃

20. Ti phase diagram

21. Designation Commerically Medium
Pure Titanium Strength
Alloys
Alloy Type Alpha Alpha-Beta
0.2% Proof Stress MPa 345 - 480 480 – 550
Tensile Strength MPa 480 - 620 600 – 650
Elongation % 20 - 25 15 -20
Tensile Modulus GPa 103 104
Torosion Modulus Gpa 45 43
Hardness HV 160 - 220 200 - 280
Density kg/1 4.51 4.48 - 4.51
Thermal Expansion 10-6/ºC 8.9 8.3
Conductivity W/mK 22 8.0
Specific Heat J/kg/ºC 525 544
Properties of Ti

22.  i) commercially pure titanium
 Ii) alpha and near alpha alloy
 Iii) alpha- beta alloy
 Iv) beta alloy

23.  pure Ti 98.5 to 99 %Ti
 pure Ti has moderate strength but good
ductility. Its has good corrosion resistance,
formability , weldability
 Very important to maintain iron content
below 0.05%
 Use low iron content filler wire , avoid steel
brushes
 Weld in annealed condition . because stress
relieved , not need in after welding

24. Alpha Ti
 similar to pure Ti.
 alpha alloys and near alpha alloys have good
weldability because of there good ductility.
 The strength of cold worked material in the HAZ
is decreased as a result of heating.
 Therefore alloy are normally weld in annealed
condition
 Its has higher strength at elevated temperature

25.  Near alpha alloy:
 Its excellent creep strength at elevated
temperature
 they are weldable but residual stress can be
high
 therefore stress relieving of weldment is
always recommended.
 Iron contamination degrades creep strength
and should be avoided

26. Beta +alpha Ti:
 Ti-6Al-4V alloy has the best weldability
 Ti-10V-2Fe-3Al has good weldability
because it is highly beta stabilized and fine
grain size during welding
 Annealing temp 750-790℃
Beta alloy:
 Beta alloy weldable in either annealed or the
heat treated condition
 Weld joints have good ductility but relatively
low strength.

27. α & pure Ti:
WELDING PROCESS:TIG,MIG, electron beam,resistance, flash
butt.
PREHEAT: weld in annealed condition
POST WELD: stress relief 400-650⁰ C
REMARK: highly reactive requires good shielding. No filler is
used below 2.5mm thickness, otherwise parent metal or
commercial purity titanium is used
(α+β)Ti:
WELDING PROCESS:TIG, electron beam, resistance, flash butt
PREHEAT: No
POSTWELD: 2hours at 538⁰ C complete aging during stress
relief

28. A=RECOMMENDED;C=POSSIBLY USABLE BUT NOT POPULAR
NO=NOT RECOMMENDED
PROCESS SMAW TIG PLASMA SMA MIG FCAW
Ti & its
alloy
NO A A NO A NO
Beta Ti:
Process : electron beam , resistance, flash butt
Preheat: weld in annealed condition
Post weld heat : -
Remark : not recommended

30.  major problem with Ti weldments Is porosity.
 It is a persistent problem and mostly it is caused
by gas bubbles formed during solidification of
weld metal.
 Oxidation form.
 Other variables affecting porosity in Ti welds:
 Heat input
 Cooling rare
 Welding speed
 Arc voltage
 Shielding gas flow rate

31.  i) ASM handbook vol 6A-welding fundamental
and process
 Ii) Nadkarni .S.V. modern arc welding
technology
 Iii)Dr.R.S.parmar: welding engineering and
technology