JJ104 Workshop Technology CHAPTER9 Welding Symbol
Transcript of 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