Copper

Resistance Welding

Lesson ObjectivesWhen you finish this lesson you will understand:•

Learning Activities1. View Slides; 2. Read Notes, 3. Listen to lecture4. Do on-line workbook

Keywords

Copper & Iron Sulfates

222 SOCuOSCu

Rosenqvist, Extractive MetallurgyMcGraw-Hill, 1974

CopperIngotElectrolytic

Refined

InductionFurnaceMelting

AWS Welding Handbook

Alloy Percent(max

soluble)

Effect

Aluminum 15 <8% Solid solution strengthening>8% Ppt and martensitic transformation

Arsenic Inhibit dezincification corrosionDetrimental to welding in Ni containing alloys

Beryllium 2 Age hardening, refractory oxideBoron Strengthen and deoxidizeCadmium 1.25 Strengthens, Class 1 Electrodes, Evaporates easily,Chromium 0.55 Age hardening, refractory oxideIron 3 SS Strengthening, ppt strengthening, corrosion resistance in

Cu-NiLead Machinability, bearing properties, poor weldabilityManganese 3 Improves hot workingNickel Complete

solubleStrength, corrosion

Phosphorus 1.7 Strengthening, deoxidizerSilicon 5.3 Deoxidizer, strength, malleability, ductility, silicon oxideTin 13.5 Strength, tin oxideZinc 32.5 Strength

Not Recommended

FairGoodExcellent

The lower thermal &electrical conductivitymaterials are weldable

AWS Welding Handbook

Resistance

Dis

tanc

ePl

ain

Car

bon

Cop

per

Welds can be made with sheets having 30% or less IACSNo Welds with IACS over 60%

Weld Force

Weld forces are usually set to 50-70% of that used forthe 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 Welding

Spot Weld Experience with 65% Cu – 35% Zn Brass

3 "Radius

Class 1 Class 2 Class 11

Increased Resistance

Min PenetrationPoor Electrode Life

Excessive penetrationElectrode Sticking

Increased Nugget Dia.

Resistance Welder manufacturers Association Bulletin # 25

Spot Welding

Tungsten or molybdenum tipped electrode are preferred to minimize tip stickingHigher Resistance = Heat SoakingLower Thermal Conductivity = Less Heat Loss

Resistance Welder manufacturers Association Bulletin # 25

More Spot Weld Experience with 65% Cu – 35% Zn Brass

Cracks Under Load When Nugget Too Close to Edge

3 "Radius

3 "Radius

Welding of Unequal Thickness Brass

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

Savage, Flash Welding, Welding Journal March 1962

Flash Welding

Copper Characteristics:• Low melting temp• Narrow Plastic RangeResult• Rapid Upset at low force• Immediate & Full Flashing Required

Rapid Upset

Low Pressure at Startto get Platen Motion Immediately

Premature Interruptionof Flashing Results inLow Temp & CL DefectsExcessive Flashing willOverheat & ImproperUpset

Flash Welding

Leaded Copper Alloys are limited to approximately 1% Lead

High Frequency Welding

Tube Butt Seam Tube Butt Seam Tube Mash Seam

HF

HF

HFInduction Coil

Nearly all Copper Alloys can by HF Welded - Tubing is a Popular Application

Electro-Brazing

Resistance

Dis

tanc

ePl

ain

Car

bon

Cop

per

Welds can be made with sheets having 30% or less IACSNo Welds with IACS over 60%

Electro-brazing

W. Stanley, Resistance WeldingMcGraw-Hill, 1950