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PERMANENT JOINTS

Riveting -Nituire

Brazing -Brazare

Soldering -Lipire

Bonding (with adhesives) -Incleiere

Welding Sudare

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filler parental (base)

material

thermally influenced base material

(structurally modified)

inter-diffusion and alloying

WELDING

. Structural modifications during welding Reduced mechanical properties ofthe welded seam in respect with base material

High residual stresses and deformations are induceddue to local heating

Thermal or thermo-mechanical stress relieving treatment is recommended

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WELDING-Methods of welding

electric-arc welding

Shielded Metal Arc Welding(SMAW)

Gas Metal Arc Welding(GMAW)

Gas Tungsten Arc Welding (GTAW)

Flux-Cored Arc Welding (FCAW)

Submerged Arc Welding (SAW)

gas welding (oxyacetylene or hydrogen flame)

resistance welding (percussion welding, resistance spot welding)

thermit welding(superheated liquid metal from a chemical reaction )

NON FUSION (friction welding, ultrasonic welding, etc)

other(plasma arc welding, laser beam welding, induction welding, etc)

FUSION

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Ce < 0.5%

WELDING -Weldability

1556

CuNiVMoCrMnCCe

++

++++=Composition

Material

Thickness 1 mm < g < 30 mm

Carbon steel - the best

Cast iron - pre-heated & special electrodes

Aluminum - MIG (inert gas) & ultrasonic heating

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MaterialArc

Welding

Oxy-

acetylenic

Welding

Electron

Beam

Welding

Resistance

WeldingBrazing Soldering

Adhesive

Bonding

Cast iron 7 9 1 1 3 1 7

Carbon steel & low-alloy

steel10 10 7 10 10 3 7

Stainless steel 10 7 7 10 10 5 7

Aluminum 7 7 7 7 7 1 10

Magnesium 7 7 7 7 7 1 10

Copper & Copper alloys 7 7 7 7 10 10 7

Nickel & Nickel alloys 10 7 7 10 10 5 7

Titanium 7 1 7 7 3 1 7

Lead 7 7 1 3 1 10 10

Zinc 7 7 1 3 1 7 10

Thermoplastics 10* 10** 1 7*** 1 1 7

Thermosets 1 1 1 1 1 1 7

Elastomers 1 1 1 1 1 1 10

Ceramics 1 1 7 1 1 1 10

Dissimilar metals 3 3 7 3 3 - 7 N/A 10

Note: 10 = Excellent, 5 = Fair, 1 = Seldom/never used. * : Heated tool; ** : Hot gas; *** : Induction.

Weldability and Joinability of Common Materials

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flexibility (combine simple shapes into very complicated structures

economy of materials & labor

adaptability to automatization

sealing capacity

uniform force flow (reduced stress concentration)

WELDING - Characterisation

Advantages

residual stresses and thermal deformations

requires positioning devices

operator ability is important

requires costly control procedures (X-rays, ultrasonic tests, etc)

Shortcomings

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butt

edge

corner

lap

Tee

WELDING-Classification

relative position of the welded parts shape of the seam

fillet weld

square weld

V-groove weld

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WELDING-Nomenclature

Root

Fusion zone

(Filler penetration)

Theoretical

throat

Face

Actual

throat

Size of weld

(Leg)

Toe

Toe

Fillet weld

Original

surface

Toe Toe

FaceFusion zone

(Filler penetration)

Root Root

Root penetration

Size of weld

(Leg)

Square weld

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WELDING-STRENGTH calculation

Welded seams should be always considered critical sections

Residual stresses are neglected

Cross section of the welded seam effective height and effective length.

aeff 2= ll

Stress calculation has a conventional character

( )2//22 ++= e =12.5compound stresses

Permissible stress calculated on the basis of the strength of parental materials

aas kk 10= k0 = 0.751

GENERAL PRINCIPLES

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WELDING-STRENGTH calculation

Butt welds

s

b

case A. Traction F

aseff

ss

F

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F Fb

b)

WELDING-STRENGTH calculation

Butt welds

effs

F

l

//// =

aseff

ss

F

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case B.bendingMb

Transverse lap weld

b

s

a

WELDING-STRENGTH calculation

conventional shear stress

as

eff

bs

a

M

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WELDING-STRENGTH calculation

Parallel lap weld

b

a

s

( ) aseffb

sasb

M