copper alloys welding
DESCRIPTION
Cu weldingTRANSCRIPT
WELDING OF COPPER AND COPPER ALLOYS
Prepared by: Gowrish
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
Applications
• Electrical conductors• Thermal insulation• Cosmetics• Fresh and salt water environments• Alkaline solutions environments
Classification of Copper and Copper Alloys
Welding consumables
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
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 elongationAluminum up to 7.5% are single phase and have only alpha phaseAluminum above 7.5% to 15% exhibits dual phase alpha and beta phase ( Hard and martenstic structure)
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
Copper Nickel Alloys
UNS numberC70100-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
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
Copper Tin Alloys
UNS numberWrought Alloys – C40400-C49080Cast 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
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
Copper Zinc Alloys
UNS numberWrought Alloys – C20500-C49080,C66400- C69950Cast 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
Some other alloying elements in Copper
Manganese• Added in range of 0.05%-3.0%• Improves the hot working characteristicsIron• Maximum solubility of iron in copper is 0.1%• Iron increase solid solution strength and
precipitation hardening
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 ductilityChromium• Copper can dissolve max of 0.55% Cr at room
temp• Cr increase electrical conductivity
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
FILLER METAL SELECTION FOR DISSIMILAR WELDING
Suggested Shielding gas selection
Joint Design
References
• Copper Development Association (CDA)• BOC world of welding• TWI Global Knowledge