Brief explanation about welding of copper and its alloys. A short table to categorize consumables used for welding copper alloys. Content help : KOBE steels limited

1. Copper and Copper Alloys
Prepared by,
Nithesh P
Venkatesh S
PSG College of Technology

2. Copper properties:
• Electrical and thermal conductivity.
• Corrosion resistance against atmosphere,
sea water and chemicals.
• Wear resistance.
• Good machinability.
• Non-magnetic.

3. Welding processes for Copper alloys
• Gas tungsten arc welding
• Gas metal arc welding
• Shielded metal arc welding
• Oxy-fuel gas welding
• Laser welding
• Electron beam welding
• Ultrasonic welding
• Resistance welding
• Flash welding
• Friction welding
• Pressure welding
Most extensively used
Non critical applications

4. Pure Copper Copper Alloys
High electrical conductivity Relatively lower electrical
conductivity
High thermal conductivity Relatively lower thermal
conductivity
Higher corrosion resistance Corrosion resistance depends
on alloying element
Lower strength compared to
alloys
Relatively higher strength than
pure metals

5. Pure Copper
Electrolytic tough
pitch copper
Oxygen free Copper
Phosphorus
deoxidized Copper
•Contains less oxygen
0.03% in the form of
Cu2o
•Presence of oxygen
amount reduces the
electrical conductivity
•It does not contain any
oxygen content so
electrical conductivity
relatively higher than
electrolytic tough pitch
copper
•Phosphorus is
sufficiently added to
promote
deoxidization and
give high thermal
conductivity.

6. Pure Copper – 1xxx series
Alloy
Designation
Content of main
alloying elements
Features
C1020 Cu-99.90% min Excellent electrical and thermal conductivity
Excellent malleability and drawability
Good corrosion and weather resistance
Good weldability
Known as “oxygen-free copper”
C1100 Cu-99.90% min ▪ Excellent electrical and
thermal conductivity
▪ Excellent malleability and drawability
▪ Good corrosion and weather resistance
▪ Known as “electrolytic tough pitch copper”
C1201 Cu-99.90%
P-0.04%
▪ Good malleability and drawability
▪ Good corrosion and weather resistance
▪ Good heat conductivity
▪ Good weldability
▪ Known as “deoxidized copper”

7. Copper alloys
• Copper-Zinc (Brass)
• Copper-Tin ( Phosphor Bronze)
• Copper- Aluminum (Aluminum Bronze)
• Copper-Silicon (Silicon Bronze)
• Copper-Nickel (Cupronickel)

8. Copper-Zinc (Brass) – 2xxx series
• Addition of zinc to copper decreases the melting
temperature, density, electrical and thermal
conductivity, and modulus of elasticity.
• Zinc additions increase the strength, hardness, ductility,
and coefficient of thermal expansion.
• Weldability problem: Zinc Vaporization results in
incomplete fusion and blow holes. So low zinc brasses
has good weldability than high zinc brasses
• Remedies: High energy density process like GTAW,
EBW used to avoid excessive zinc vaporization

10. Copper-Tin ( Phosphor Bronze) – 5xxx Series
• Tin bronzes are also called as 'phosphor bronzes' due to
the presence of small amount (0.01–0.5%)
of phosphorous used as deoxidizer in casting.
• The wrought alloy usually contain 1-10% tin. Copper
containing up to 6% tin are soft alloys whereas those
containing more than 6% tin are hard.
• Weldability Problem: wide freezing ranges so it is more
susceptible to Hot Cracking
• Remedies: Short peening after each pass and multi pass
welding to reduce the thermal stress

12. Copper - Aluminum (Aluminum Bronze) – 6xxx series
• Its containing about 3-15% Aluminum
• Types 1: Non Heat Treatable ( Al < 7 %) (single phase)
• Type 2 : Heat Treatable ( Al : 9.5 – 11.5%) ( Dual phase)
• Alpha phase is hot-short .
• Beta phase more ductile and tough.
• Having α+β phase reduces the hot cracking
susceptibility.
• Weldability problem : Formation of Al203 during
welding cover the molten weld metal Causing
insufficient fill and porosity
• Remedies: Welding with DCEP or AC polarity

14. Copper-Silicon (Silicon Bronze)
• It offers high strength and excellent corrosion resistance,
and has good weldability.
• Weldability advantages : Silicon bronzes are
comparatively better weldable due to their low thermal
conductivity and thus low heat loss to the surrounding
base metal, good deoxidization of the weld metal by the
silicon.
• Main disadvantage is hot-short at elevated
temperatures.
• Remedies: Reduce preheating and restrict inter-pass
temperature not more than 70 deg C.

16. Copper-Nickel (Cupronickel) – 7xxx series
• Iso-morphous ( Completely soluble in one another)
• Copper-nickel alloys have moderately high tensile strengths
that increase with nickel content.
• They are less thermal & electrical conductive
• These alloys are ductile, relatively tough, and well resistible to
the seawater corrosion
• Weldability problem : Hot cracking and porosity.
• Remedies:
 Preheat should be avoided & Inter pass temperature should
be kept below 100 deg C to avoid hot cracking.
 Having Titanium content in filler metal during welding of
cupronickel helps in avoiding porosity

18. Weldability Concerns
• Copper alloys has less thermal conductivity than copper,
In that case copper alloys considered to be good
weldable than pure copper.
• Most of the copper alloys are hot-short, so preheating to
high temperature itself may produce problem in copper
alloys.
• We can obtain good penetration and good fusion in
copper alloys even without much preheating since these
alloys less thermal conductive.
• For pure copper – High preheat & He shielding
• For copper alloys – Less preheat & Ar shielding

20. Fillers – Chemical composition

21. Filler properties and applications

22. Reference
• Arc welding of non-ferrous metals – KOBE
steels limited, 5th edition,.