Copper and copper alloys are widely used for their electrical and thermal conductivity. Major copper alloys include aluminum bronze, nickel copper, tin bronze, and zinc bronze. Aluminum bronze contains 3-15% aluminum and has increased strength but decreased ductility. Nickel copper contains 3-30% nickel and has increased strength and toughness. Tin bronze contains 2-10% tin and has increased fatigue resistance and hardness. Zinc bronze contains 20-36% zinc and has increased strength and thermal expansion. When welding copper alloys, factors like dual phase microstructures, oxide inclusions, and element evaporation must be considered and addressed through techniques like preheating and post-heating. Dissimilar welds

1. WELDING OF COPPER AND
COPPER ALLOYS
Prepared by: Gowrish

2. Copper Properties
• Face centre cubic structure
• High electrical and thermal conductivity
• Density three times higher than aluminum
about 8.94 mg/m3
• Good machine ability and malleability

3. Applications
• Electrical conductors
• Thermal insulation
• Cosmetics
• Fresh and salt water environments
• Alkaline solutions environments

4. Classification of Copper and Copper Alloys

5. Welding consumables

6. Copper alloys
To improve the properties of copper and make it suitable for
industrial applications, some alloys are added in different
proportions
Major alloys added are,
 Aluminum
 Nickel
 Tin
 Silicon
 Iron
 Boron
 Chromium
 Manganese
 Zinc

7. Copper Aluminum(Aluminum
Bronze)
UNS number
C95200-C95900(CAST product)
C60600-C64400(Wrought product)
Aluminum added in the proportion of 3
to 15%
Aluminum increase strength, yield
strength and hardness but decrease the
elongation
Aluminum up to 7.5% are single phase
and have only alpha phase
Aluminum above 7.5% to 15% exhibits
dual phase alpha and beta phase ( Hard
and martenstic structure)

8. Copper Aluminum(Aluminum Bronze)
Conti’..
Precautions in welding Aluminum Bronze
• Dual Phase Aluminum Bronze shall be
preheated to avoid HAZ due to Beta phase
• Aluminum oxide shall be cleaned prior to
welding which is hygroscopic and creates
porosity in weldment

9. Copper Nickel Alloys
UNS number
C70100-C72950 ( Wrought Alloys)
C96200-C96900 (Cast Alloys)
• Copper can completely dissolve Nickel in any
proportions
• Addition of Ni from 3% to 30%
• Ni increase strength and toughness
• Ni retains some austentic structure at room temp
• Titanium added as deoxidizer in weld
consumables

10. Copper Nickel Alloys
(Contin’..)
Precautions
• Sulfur and Lead embrittlement is usual and
such impurities is restricted to 0.02% max
• Preheating and post heating is not
recommended due to room temp austenitic
structure
• This alloys cannot hardened by heat treatment

11. Copper Tin Alloys
UNS number
Wrought Alloys – C40400-C49080
Cast Alloys – C94700-C94900
• Tin added in range of 2%-10% in addition to deoxidizer
Phosphorus(0.03%-0.04%)
• This alloy also known as Phosphorus Bronze
• Tin increase fatigue resistant, wear resistance and hardness
in cold worked condition

12. Copper Tin Alloys
(Conti’…)
Precautions
• Tin melting point is about 480deg cel and
upon further melting, tin will start to boil off
and cause porosity
• Copper tin alloys with addition of Lead as a
deoxidizer shall not welded due to radioactive
emission
• Cast form Copper Tin alloys have dendrites
formation issue

13. Copper Zinc Alloys
UNS number
Wrought Alloys – C20500-C49080,C66400-
C69950
Cast Alloys – C83300-C86800
• Zinc added in the range of 20% -36 % are single phase
• Zinc above 36% are dual phase and exhibit hardest micro structure
• Dual phase can be hardened by heat treatment (Q&T)
• Zinc addition increase strength, coefficient of thermal expansion
• Mainly used for fresh water transport system and decorative
purpose
• Preheat and post weld is recommended for dual phase copper zinc
alloys

14. Some other alloying elements in
Copper
Manganese
• Added in range of 0.05%-3.0%
• Improves the hot working characteristics
Iron
• Maximum solubility of iron in copper is 0.1%
• Iron increase solid solution strength and
precipitation hardening

15. Some other alloying elements in
Copper (contin’…)
Silicon
• Solubility of silicon in copper is 3% max at room
temp
• Silicon acts as a deoxidizer and improve
malleability and ductility
Chromium
• Copper can dissolve max of 0.55% Cr at room
temp
• Cr increase electrical conductivity

16. Issue of welding Copper with other
materials
• Copper to Stainless steel welding
Copper can’t dissolve Chromium and welding
this dissimilar combination, Stainless steel
shall be buttered with 99%Ni alloy and
welded by Copper alloy consumable

17. FILLER METAL SELECTION FOR DISSIMILAR WELDING

18. Suggested Shielding gas selection

19. Joint Design

20. References
• Copper Development Association (CDA)
• BOC world of welding
• TWI Global Knowledge