jj104 workshop technology chapter9 welding symbol

7/21/2019 JJ104 Workshop Technology CHAPTER9 Welding Symbol

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Arc voltage the voltage across the welding arc

Arc Length the distance between the tip of the electrode and the

weld puddle

Bead Result of the weld deposited on the metals being joined.

Weld puddle the molten metal form a pool

Slag outer layer of the weld bead deposited during welding

(SM!"

Deposited Metal-#iller metal that has been added during a welding

operation

Depth of Fusion the distance from the original surface of the base

metal to that point at which fusion ceases in a

welding operation.


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!eld puddle % weld pool

rc length

!eld &ead'epth of fusion% weld penetration


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leg )he distance from the root to the toe of the fillet weld. )he si*e of the fillet weld isdetermined by the length of its legs.

Throat )he shortest distance between the weld root and the weld face. )he throatdetermines a fillet weld+s si*e and strength.

Toe point at which the weld face and the base metal meet.

Face )he e,posed surface of a weld on the side from which welding occurs.

Root)he depth that a weld e,tends into the joint root


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The importance ofwelding symbolthe weld that needs to be done

these weld symbols will be easier to read.

they tell you the type of weld to dothe size of the weld you should do and other

information about how you will process it ornish the job.

helps to keep things form getting to confusing

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Leader

Reference Line

Tail

!elding symbol is based on 3S4%!S 2.5 Standard and symbols forwelding Bra!ing and "on-destructive testing


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Frequently Used Symbol Elements For

Structural Welding


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Fillet Weld

Weld around

Arrow side

Opposite side

Specification Result


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undercutting is a defect that appears as a groove in the parent metal directly

along the edges of the weld. 4t is most common in lap fillet welds5 but can also

be encountered in fillet and butt joints. )his type of defect is most commonly

caused by improper welding parameters6 particularly the travel speed and arc

voltage.

)he arc length should be 7ept short5 not only to avoid undercutting but to

increase penetration and weld soundness


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)he most common causes of porosity are atmosphere contamination5 e,cessively

o,idi*ed wor7 piece surfaces5 inade8uate deo,idi*ing alloys in the wire and the

presence of foreign matter. tmospheric contamination can be caused by9

1" 4nade8uate shielding gas flow.

2" :,cessive shielding gas flow. )his can cause aspiration of air into the gas

stream.

$" Severely clogged gas no**le or damaged gas supply system (lea7ing hoses5

fittings5 etc."


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4ncomplete fusion weld pool did not wet surface of wor7piece due to

fast traveling speed. )he molten material solidified rapidly and not enough

#usion form.


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Spatter; surface damage caused by molten metal from arc or weld pool.rc length too long.


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pieces of slag trapped inside solidified weld pool6 may result from

e,cessive stirring in weld pool5 or failure to remove slag from prior weld


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)his type of defect is found in any of three ways9

1" weld bead does not penetrate the entire thic7ness of the base plate.2" )wo opposing weld beads do not interpenetrate.

$" weld bead does not penetrate the toe of a fillet weld but only bridges across it.


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2:,cessive penetration

4ncomplete penetration insufficient heating during welding for weld pool to penetrate

to opposite side (or centerline" of weld6 results in a gap behind%under weld

jj104 workshop technology chapter9 welding symbol

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