Advanced Metal Seminar

8/18/2019 Advanced Metal Seminar

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FILLET WELDS

• A weld of approximately triangular cross section joining two surfaces, approximate

right angles to each other.

• Fillet welds are most common and used widely.

• The fillet weld is used to make lap joints, corner joints, and t- joints.

FILEET WELD TERMS

• Root : The root of the weld is the point where the faces of the metallic members me

• Throat Thickness : The theoretical throat of a weld is the shortest distance fro

root to the hypotenuse of the triangle.

• Leg length or Size of weld : The side of the triangle is taken as the leg length or siz

weld.


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Types of fillet weld:

a!"ide fillet

b!#nd fillet

c! $iagonal fillet

$iagnol fillet weld

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Weld specifications IS!""#$""%&:

Mini'(' size of weld:

• The size of fillet weld should not be less than % mm nor more than the thickn

the thinner part joined.

• To ensure fusion, minimize distortion, and to a&oid the risk of cracking '" ()

*))+ and '" ( pro&ide for a minimum size weld based on the thickness of

pieces being joined .

MI)IM*M*M SI+E ,F - SI).LE R*) FILLET WELD -S /ER !""#$""%&

Thickness of thicker part

&er, mm /p to and including, mm

'ini'(' size 0''

- ) %

) *) 0

*) %*

%* 0) ( for first run,) for minimum

"ize of weld

)ote 11 when the minimum size of the fillet weld gi&en in the table is greater than the

thickness of the thinner part, the minimum size of the weld should be e2ual to the thickne

the thinner part. the thicker part shall be ade2uately pre-heated to pre&ent cracking of the

)ote $ 1 where the thicker part is more than 0)-mm thick, special precautions like pre-he

should be taken.

Ma2i'(' fillet weld size along edges:

The maximum size of fillet weld used along the edges of pieces being jointed is limit

pre&ent the melting of base material at the location where the fillet would meet the cor

the plate, if the fillet were made to the full plate thickness. The maximum size is e2ual

thickness of the plate.

a!.Along the edge of the plate, less than -mm thick, the maximum size is e2ual to the

thickness of the plate.

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$esirable Acceptable 3ot acceptable because of

reduced throat thickness

b! where the fillet weld is applied to the s2uare edge of a plate of thickness greater than

size of the weld should be at least .0 mm less than the edge thickness. This limit is specif

such that the total strength may be de&eloped without o&erstressing the adjacent metal. dia

c! where the fillet weld is applied to the rounded toe of the rolled steel section, the size o

weld should not exceed 4 of the thickness of the section at the toe.

diagrams

d& #nd fillet weld normal to the direction of force should be of une2ual size with t

thrat thickness of the weld should not be less than ).0 t,where t thickness of the part.the

thickness of the weld should be negotiated at a uniform slope.

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End fillet weld nor'al to direction of force

MI)IM*M EFFE3TI4E LE).T5 ,R -RE- FILLET WELD:

• 5hen placing a weld fillet weld, though the welder tries to build up the weld to its f

dimension from the beginning, there is always a slight tapering off where the weld

and where it ends.

• Therefore, a minimum length of four times the size of the weld is specified. 'f this

re2uirement is not met, the size of the weld should be one fourth of the effecti&e len

• For the abo&e reasons, the effecti&e length is taken e2ual to its o&erall length minus

twice the size of weld.

• #nd returns are made e2ual to twice the size of the weld to relie&e the high stress

concentration at the ends.

• Effecti6e Throat Thickness1 the #ffecti&e Throat thickness of a fillet weld shall n

less than % mm and generally not exceed ).+t,or .)t under special circumstances- i

thickness of thinner plate.

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a

a

Throat 6 a x cos70o

6 ).+)+ a

a

a

Throat 6 a x cos70o

6 ).+)+ a

• For stress calculations, the effecti&e throat thickness should be taken as 8 times fill

size, where 8 is a constant. 9alues of 8 for different angles between tension fusion

faces are gi&en in Table *. Fillet welds are normally used for connecting parts whos

fusion faces form angles between ): and *):

Table *. 9alue of 8 for different angles between fusion faces

STRESS DISTRI7*TI,) I) WELDED 8,I)TS9

• The stress distribution in welded joints is complex and non-uniform figure show ty

stress distribution at ser&ice load for longitudinal fillet welds in a lap joint.

• The actual &ariation of shear stress in the weld from points A to ; depends on the l

of the weld and also the ratio of the width of plates being joined distribution.

•Thus it is seen that there is a series stress concentration at the edge of the plate.in

to control it,the length of the longitudinal side!fillets should not be less than the

of the plate.

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• The une&en stress distribution increases as the width of the plate increases.for this r

,the perpendicular distance between longitudinal fillet welds is limited to tim

thickness of the thinner plate joined.

Failure


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Slot Welds or /l(g Welds

• 'n certain instances, the lengths a&ailable for the normal longitudinal fillet

may not be sufficient to resist the loads. 'n such a situation, the re2uired strength m

built up by pro&iding slot or plug welds.

• /l(g welds and slot welds are used join o&erlapping members, one of whic

holes round for plug welds, elongated for slot welds! in it. 5eld metal is deposi

the holes and penetrates and fuses with the base metal of the two members to form

joint.

Slot weld and pl(g weld

/l(g and slot weld

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Specifications for design of pl(g and slot weld IS !1#1;;&:

a!The width or diameter should not be less than three times the thickness or

*0 mm whiche&er is greater

b! >orners at the enclosed ends or slots should be rounded with a radius not less

than .0 times the thickness or * mm whiche&er is greater, and

c! The distance between the edge of the part and the edge of the slot or hole, or

between adjacent slots or holes, should be not less than twice the thickness

and not less than *0 mm for the holes.

• The limitations gi&en in specifications for the maximum sizes of plug and slot wel

necessary to a&oid large shrinkage, which might be caused around these welds

they exceed the specified sizes.

• The strength of a plug or slot weld is calculated by considering the allowable stres

its nominal area in the shearing plane.

• This area is usually referred to as the faying surface and is e2ual to the area of c

at the base of the slot or plug. The length of the slot weld can be obtained from

following relationship1

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Advanced Metal Seminar