Welding Method

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CHAPTER 27&29
INTRODUCTION TO WELDING & FUSION
WELDING PROCESS
Dr. Tasnim Firdaus Ariff

Welding Fundamentals
Overview of Welding Technology
2. The Weld Joint
3. Features of a Fusion Welded Joint
1.

2

Joining and Assembly Distinguished
Joining - welding, brazing, soldering, and adhesive bonding
 These processes form a permanent joint between parts
Assembly - mechanical methods (usually) of fastening parts
together
 Some of these methods allow for easy disassembly, while
others do not

3

Welding
Joining process in which two (or more) parts are coalesced at their contacting surfaces by application of heat and/or
pressure
 Many welding processes are accomplished by heat alone, with no pressure applied
 Others by a combination of heat and pressure
 Still others by pressure alone with no external heat
 In some welding processes a filler material is added to
facilitate coalescence

4

Limitations and Drawbacks of Welding
Most welding operations are performed manually and are
expensive in terms of labor cost
 Most welding processes utilize high energy and are inherently dangerous
 Welded joints do not allow for convenient disassembly
 Welded joints can have quality defects that are difficult to detect


5

Types of Welding Processes
Some 50 different types of welding processes have been
catalogued by the American Welding Society (AWS)
 Welding processes can be divided into two major categories: 

 Fusion welding
 Solid state welding

6

Five Types of Joints
1.
2.
3.

4.
5.

7

Butt joint
Corner joint
Lap joint
Tee joint
Edge joint

Butt Joint
Parts lie in same plane and are joined at their edges

Figure 30.2 Five basic
types of joints: (a) butt

Corner Joint
Parts in a corner joint
form a right angle and
are joined at the
corner of the angle

Figure 30.2 (b) corner

Lap Joint
Consists of two
overlapping parts

Figure 30.2 (c) lap

Tee Joint
One part is perpendicular
to the other in the
approximate shape of the
letter "T"

Figure 30.2 (d) tee

Edge Joint
Parts in an edge joint
are parallel with at least
one of their edges in
common, and the joint
is made at the common
edge(s)

Figure 30.2 (e) edge

Types of Welds
Each of the preceding joints can be made by welding
 Other joining processes can also be used for some of the joint types
 There is a difference between joint type and the way it is welded - the weld type


13

Fillet Weld


Used to fill in the edges of plates created by corner, lap, and tee joints

 Filler metal used to provide cross section in approximate shape of a right triangle  Most common weld type in arc and oxyfuel welding
 Requires minimum edge preparation

Figure 30.3 Various forms of fillet welds: (a) inside single fillet corner joint; (b) outside single fillet corner joint; (c) double fillet lap joint; and (d) double fillet tee joint. Dashed lines show the original part edges.

14

Groove Welds


Usually requires part edges to be shaped into a groove to facilitate weld penetration

 Edge preparation increases cost of parts fabrication
 Grooved shapes include square, bevel, V, U, and J, in single or double sides  Most closely associated with butt joints

Figure 30.4 Some groove welds: (a) square groove weld, one side; (b) single bevel groove weld; (c) single V-groove weld; (d) single U-groove weld; (e) single J-groove weld; (f) double V-groove weld for thicker sections. Dashed lines show original part edges. 15

Spot Weld
Fused section between surfaces of two plates
 Used for lap joints
 Closely associated with resistance welding

Figure
30.6 (a)
Spot
weld

Welding Methods and Procedures
1.
2.
3.

4.
5.
6.
7.
8.

17

Arc Welding
Resistance Welding
Oxyfuel Gas Welding
Other Fusion Welding Processes
Solid State Welding
Weld Quality
Weldability
Design Considerations in Welding

Two Categories of Welding...
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