Fillet Welding [PDF]

Zitiervorschau

FILLET WELDING Rhishikesh Kulkarni

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OBJECTIVES • Understanding Importance of Fillet , Its Aesthetics and Cost. • To Create consumable wastage awareness due to excessive fillet sizes. • Understanding & Control of fillet size variations in various positions.

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CONTENTS A. INTRODUCTION TO FILLET B.FILLET NOMENCLATURE C.FILLET WELD DESIGN - BASICS D.FILLETS USED TO MAKE FIVE BASIC JOINTS E. FAULTY WELD FILLET SIZES & PROFILES F. FILLET WELDING TECHNIQUES G. VARIOUS FILLET PROFILES & WELDING SYMBLOLS H. TEST PAPER PDF created with pdfFactory Pro trial version www.pdffactory.com

A. INTRODUCTION TO FILLET

Symbol Of Fillet weld

Definition : “ Weld of Approximately triangular cross section joining two surfaces nearly at right angles to each other.” • Fillet welds are used to join corner, T and Lap joints . • Fillet Joints are economical and requires no edge preparation. PDF created with pdfFactory Pro trial version www.pdffactory.com

B. FILLET WELD NOMENCLATURE

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B. FILLET WELD NOMENCLATURE ( Contd..) • Base Metal : Metal to be welded. • Bond Line: Junction of Weld Metal and Base Metal. • Depth of Fusion: Distance that fusion extends into base metal. • Face of Weld: Exposed surface of weld on the side from which the welding was done. • Leg of a Fillet weld: Distance from a root of a joint to the toe of the fillet weld. • Root of Weld: Point at which the bottom of the weld intersects the base metal surface. • Throat of Fillet weld: Shortest distance from the root of the fillet weld to its face. • Toe of a weld: Junction between the face of the weld and the base metal. PDF created with pdfFactory Pro trial version www.pdffactory.com

C. FILLET WELD DESIGN - BASICS • Fillet welds are least expensive than groove weld as edge preparation cost is less. • Fillet welds are expected to have equal leg lengths i.e ideally face of the fillet should be at 45 degrees angle. • In normal type of fillets , strength of fillet depends on throat Size. •Throat Size = 0.707 x leg length.

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C. FILLET WELD DESIGN - BASICS • Doubling the Fillet Size ( Leg length ) doubles the throat dimensions also doubles the strength of the fillet . But it increases the cross sectional area weight by four times . • Single fillet welds are extremely prone to cracking , root of weld is subjected to cracking specifically for T, corner & Lap joints. •Remedy for this is to make double fillets which prohibits the tensile load from being applied to the root of the fillet. •Please refer the F ( FORCE) arrowhead in Figure 19.25. (Fillet used to make five basic joints)

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C. FILLET WELD DESIGN - BASICS ( contd…)

B

A 10

20 10

20

Diagram A Shows Leg Length = 10 mm Diagram B shows leg length = 20 mm. Area of Fillet A = 50 mm2 Area of Fillet B = 200 mm2 Suppose welding to be carried out on 1 meter Length. I.e Welding Length ( L) = 1000 mm PDF created with pdfFactory Pro trial version www.pdffactory.com

C. FILLET WELD DESIGN - BASICS ( contd…) Welding Volume = Fillet A = 50 Cm3 Fillet B = 200 Cm3 Weld Deposit = Fillet A = 390 gms. Fillet B = 1560 gms. Thus, Doubling the Fillet Size ( Leg length ) doubles the throat dimensions But increases the cross sectional area weight and electrode Consumption by four times .

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D. FILLETS USED TO MAKE FIVE BASIC JOINTS

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E. FAULTY FILLET WELD SIZES & PROFILE • Faulty weld sizes refers to undersize weld or variable leg lengths than required. Faulty profiles refers to excessive concavity, excessive convexity, unequal leg lengths & irregular weld face.

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E.FAULTY FILLET WELD SIZES & PROFILE ( Contd…) 1.

Excessive Convexity

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E.FAULTY FILLET WELD SIZES & PROFILE ( Contd…) 1. Excessive Convexity : It is the weld metal lying outside the plane joining the weld toes. Normally Called as ”Reinforcement.” Causes: A.Deposition of excess volume of a cold metal. B.Use of Incorrect ( Low) welding current. C.Improper welding technique. NOTE :Excessive Convexity is also associated with overlapping toes of the weld giving rise to notch effect & stress Concentration affecting fatigue life of a component seriously.

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E.FAULTY FILLET WELD SIZES & PROFILE ( Contd…) 1.

Excessive Convexity ( Contd..):

Acceptance: As per AWS D 1.1 limits for this imperfection relate the height of the excess metal to the width of bead with maximum values ranging from 3 mm for a stringent quality and 5 mm for a moderate quality levels.

Width of weld Face

Maximum Convexity

W