Transcript No Slide Title

Copper
Resistance Welding
Lesson Objectives
When you finish this lesson
you will understand:
•
Keywords
Learning Activities
1. View Slides;
2. Read Notes,
3. Listen to lecture
4. Do on-line workbook
Copper & Iron Sulfates
Electrolytic
Refined
Copper
Ingot
Cu2 S  O2  Cu  SO2
Rosenqvist, Extractive Metallurgy
McGraw-Hill, 1974
Induction
Furnace
Melting
AWS Welding Handbook
Alloy
Aluminum
Arsenic
Beryllium
Boron
Cadmium
Chromium
Iron
Lead
Manganese
Nickel
Phosphorus
Silicon
Tin
Zinc
Percent
(max
soluble)
15
Effect
<8% Solid solution strengthening
>8% Ppt and martensitic transformation
Inhibit dezincification corrosion
Detrimental to welding in Ni containing alloys
2
Age hardening, refractory oxide
Strengthen and deoxidize
1.25
Strengthens, Class 1 Electrodes, Evaporates easily,
0.55
Age hardening, refractory oxide
3
SS Strengthening, ppt strengthening, corrosion resistance in
Cu-Ni
Machinability, bearing properties, poor weldability
3
Improves hot working
Complete Strength, corrosion
soluble
1.7
Strengthening, deoxidizer
5.3
Deoxidizer, strength, malleability, ductility, silicon oxide
13.5
Strength, tin oxide
32.5
Strength
AWS Welding Handbook
Not Recommended
Fair
Good
Excellent
The lower thermal &
electrical conductivity
materials are weldable
Plain Carbon
Copper
Distance
Welds can be
made with sheets
having 30% or
less IACS
No Welds with
IACS over 60%
Resistance
Spot Welding
Weld Force
Weld forces are usually set to 50-70% of that used for
the same thickness uncoated plain carbon steel
Spot Welding
Weld Current: Higher than for plain carbon steel
Weld Time: Shorter than for plain carbon steel
Spot Weld Experience with 65% Cu – 35% Zn Brass
3"
Radius
Class 1
Increased Resistance
Class 2
Min Penetration
Poor Electrode Life
Class 11
Excessive penetration
Electrode Sticking
Increased Nugget Dia.
Resistance Welder manufacturers Association
Bulletin # 25
Spot Welding
Tungsten or molybdenum
tipped electrode are preferred to
minimize tip sticking
Higher Resistance = Heat
Soaking
Lower Thermal Conductivity =
Less Heat Loss
More Spot Weld Experience with 65% Cu – 35% Zn Brass
Cracks Under Load
When Nugget Too Close
to Edge
Resistance Welder manufacturers Association
Bulletin # 25
Welding of Unequal Thickness Brass
3"
Radius
3"
Radius
Seam Welding
Problems:
• Shunting of Weld Current
• High thermal conductivity
• Low Electrical Contact Resistance
Result:
• Limited Alloys Seam Weldable
• Need Electrical Conductivity less than 30% IACS
Flash Welding
Flash Welding
Rapid Upset
Premature Interruption
of Flashing Results in
Low Temp & CL
Defects
Excessive Flashing will
Overheat & Improper
Upset
Copper Characteristics:
• Low melting temp
• Narrow Plastic Range
Result
• Rapid Upset at low force
• Immediate & Full Flashing Required
Low Pressure at Start
to get Platen Motion
Immediately
Savage, Flash Welding,
Welding Journal March 1962
Flash Welding
Leaded Copper Alloys are limited to approximately 1% Lead
High Frequency Welding
HF
Induction Coil
HF
HF
Tube Butt SeamTube Butt Seam
Tube Mash Seam
Nearly all Copper Alloys can by HF Welded - Tubing is a
Popular Application
Electro-Brazing
Plain Carbon
Copper
Distance
Welds can be
made with sheets
having 30% or
less IACS
No Welds with
IACS over 60%
Resistance
Electro-brazing
W. Stanley, Resistance Welding
McGraw-Hill, 1950