Clad Materials

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

Steel - Aluminum Cladding

Cleaning

Rollinga. Coldb. 600-750 F

Post-Heating ~ 1000F

Hansen, Const of Binary AlloysMcGraw-Hill, 1958

Aluminum

Steel

FeAl3, Fe2Al5

(Brittle)Si > 0.25% in SteelTends to Reduce Brittle Iron-Alumindes Thus Higher Post Roll Temperatures can be employedSteel

Steel

Aluminum

Steel

Steel

Aluminum

Oikawa et al, RSW of Steel & Al Sheet Using Insert,Science & Tech of Welding & Joining, vol4, 1999

Fe-Al Clad Material

Table of Steel and Aluminum Properties

MP Elect ResistmicroOhm Cm

Therm CondW/(m K)

Fe 2700-2800 F ~15 ~51Al 890-1180 F ~5 167

Heat Flow in Spot Welding (Fe - Al)

Steel

Aluminum

Fe

Al

Fe

Al

The lower MP of AluminumCauses Rapid Nugget GrowthWhich Can Lead to Al ExpulsionA Larger Electrode on the AlSide Might Help

Chang et al, Spot Welding Al to Steel,Practical Welding Today, May/June 1999

Steel

Aluminum

Fe-Al Weld

Oikawa et al, RSW of Steel & Al Sheet Using Insert,Science & Tech of Welding & Joining, vol4, 1999

Fe-Al

Fe-Fe/Al-Al

IMC = Fe2Al5

Chang et al, Spot Welding Al to Steel,Practical Welding Today, May/June 1999

Oikawa et al, RSW of Steel & Al Sheet Using Insert,Science & Tech of Welding & Joining, vol4, 1999

Fracture Occurred on Tensile LoadAt the IMC Interface

With Thinner Aluminum Sheet,Fracture Occurred by NuggetPull-out

Chang et al, Spot Welding Al to Steel,Practical Welding Today, May/June 1999

Heat Flow in Spot Welding (Fe - Trans - Al)

Steel

Steel

Aluminum

Aluminum

Oikawa et al, RSW of Steel & Al Sheet Using Insert,Science & Tech of Welding & Joining, vol4, 1999

Steel

AluminumSteel Aluminum Transition

Fe-Fe/Al-Al Weld

Chang et al, Spot Welding Al to Steel,Practical Welding Today, May/June 1999

Weld With 2 mm Steel

Chang et al, Spot Welding Al to Steel,Practical Welding Today, May/June 19991 MM Thick Steel (Faster Cooling)

Shrinkage Voids in AlDue to Faster Cooling

Oikawa et al, RSW of Steel & Al Sheet Using Insert,Science & Tech of Welding & Joining, vol4, 1999

Chang et al, Spot Welding Al to Steel,Practical Welding Today, May/June 1999

Titanium

Aluminum

Aluminum - Titanium

Properties of Ti & Al

MP Elect ResistmicroOhm Cm

Therm CondW/(m K)

Ti ~3035 F 57-171 6-16Al 890-1180 F ~5 167

Ti-Ti Welds

AluminumHigh ConductivityLow ResistivityLow MP

TitaniumLow ConductivityHigh ResistivityHigh MP

Ti melts, Heat flows to Al (melts a little because lower MP)but because of High Al Conductivity, Heat conducted to Electrodes

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

The high MP & high Resistance Ti pushes heat into the AluminumCausing melting and expulsion along the Interface

Ti-Al WeldsElectrode IndentedForcing Al Expulsion

Ti

Ti

Al

Al

Ti

Al

TiAl

Ti to Al Weld

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

No Current RangeExpulsion

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

Oxide film betweenAl & Ti prevents interdiffusion

This also promotesInterfacial Failure

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

Al-Al WeldsCase 1 Electrode Free

to MoveCase 2 Electrode

Restrained

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

No RestraintWith Restraint

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

Watanabe, Resistance Welding of Ti/Al clad plate,Welding International, May 1996

AluminumStainless Steel

Stainless Steel Clad Aluminum & Copper

CopperStainless Steel

Hot Rolled