Solid‐State Welding, Brazing Soldering, Mechanical Fastening

Laser/E‐beam Welding

Feature of Fusion Welding

Fusion Zone

Base Metal

Fusion line

Solid‐State Welding

• Liquid phase is not present

• High temperature promotes bonding

• Pressure promotes bonding by plastic deformation

• Does not require consumable electrodes, shielding gases or flux

Diffusion Welding

• Bonding promoted by diffusion• Slow process• T > 0.5 TM• Pressure applied by dead weights, press, differentialgas pressure

• Parts are then heated in a furnace or by electricalresistance

• Generally suited for joining dissimilar metals• Also used for reactive metals (Ti, Be, Zr) andcomposites

Initial 'point' contact

Yielding and creep

Final yielding and creep

Continued vacancy diffusion

Bonding is complete

Diffusion Welding Process

Military aircraft has more than 100 diffusion‐bonded parts

Friction Welding

Friction Welding

www.directindustry.com

Ultrasonic Welding

www.lumotech.co.za

Typical applications include batteries, thread guides, textile cutting equipment and heavy duty electrical fuses.

Brazing

Brazing

Brazing is normally done TL > 450 °C 

Brazing Techniques:Controlled Atmosphere Brazing (CAB)Vacuum Brazing (VB)Salt Bath BrazingFlame Brazing

Brazing

The key is surface preparation before brazing

H2

O

CrFe

in SS

Brazing Fillers

Filler Metal Composition Aprox. Brazing Temperature(oC)

Base Metals

Al and Si 90 Al, 10Si 600 Al

Cu,P 95 Cu,5P 850 Cu,Ni

Cu,Zn 60Cu,40Zn 925 Steels, Cast Iron

Au,Ag 80Au,20Ag 950 SS, Ni‐alloys

Ni alloys Ni,Cr, Others 1120 SS, Ni‐alloys

Ag‐alloys Ag,Cu,Zn,Pd 730 Ti, Tool Steel

Brazed Joints

Brazing Techniques

Soldering

hacknmod.com

The key is surface preparation before soldering

Common Solders

Filler Metal Composition Aprox. Brazing Temperature(oC)

Applications

Pb‐Ag 96Pb, 4Ag 305 Elevatedtemp. joints

Sn‐Sb 95Sn, 5 Sb 238 Plumbing & heating

Sn‐Pb 63Sn, 37Pb60Sn, 40Pb50Sn,50Pb40Sn, 60Pb

183188199207

Electronic

Sn‐Ag 96Sn,4Ag 221 Food containers

Sn‐Ag 91Sn, 9Ag 199 Aluminumjoining

Adhesive Bonding

• Joining with adhesives– Natural: Starch, dextrin, soya flour, animal products

– Inorganic: Sodium silicate, magnesium oxychloride

– Synthetic organics: Epoxy, acrylics, Urethane, Silicon etc

Adhesive Bonding

Joints

Failure

Tensile Shearing Cleavage Peel‐off

Process Capabilities

• Joins a wide variety of similar and dissimilarmetallic and non‐metallic materials andcomponents of different shapes, sizes andthicknesses

• Designed to withstand shear, compressive andtensile forces

• Combined with mechanical fastening toimprove bond strength

• Aerospace, automotive, appliances, buildingproducts– Attachment of rear view mirrors to windshields

– Automotive brake lining assemblies

– Laminated windshield glass

– Helicopter blades

– Aircraft bodies

Mechanical Fastening

• Threaded fasteners: Nuts and Bolts, screws

• Rivets: Most common method of permanent or semi‐permanent joining– (a) solid, (b) tubular, ( c) split, (d) compression