Welding | Definition, Types, Advantages, Disadvantages

Table of Contents

What is welding?

Welding is a fabrication process which is used to join materials (usually metals), by causing fusion. This Fusion is done with the help of temperature (and or pressure). It is most common fabrication process, usually used with steels or stainless steel. In this article we will also try to understand some disadvantages and advantages of welding.

Joints obtained by welding are permanent in nature which means to detach welded parts we have to damage them.

Types of welding

According to place and work material, it has different types.

1. Oxy-fuel welding

It uses fuel gases and oxygen to weld metals. It requires filler material.

2. Shielded metal arc welding (SMAW)

It is a manual arc welding process that uses a consumable electrode covered with a flux to lay the weld.

3. Gas tungsten arc welding (GTAW)

It is an arc welding process that uses a non-consumable tungsten electrode to produce the weld.

The weld area and electrode is protected from oxidation or other atmospheric contamination by an inert shielding gas (argon or helium). It uses filler metal, though some welds, known as autogenous welds, do not require it.

4. Gas metal arc welding (GMAW)

It is a welding process in which an electric arc forms between a consumable wire electrode and the workpiece metal, which heats the workpiece metal, causing them to melt and join.

5. Submerged arc welding

It is a common arc welding process. It requires a continuously fed consumable solid or tubular (metal cored) electrode.

The molten weld and the arc zone are protected from atmospheric contamination by being “submerged” under a blanket of granular fusible flux consisting of lime, silica, manganese oxide, calcium fluoride, and other compounds.

When molten, the flux becomes conductive, and provides a current path between the electrode and the work. This thick layer of flux completely covers the molten metal thus preventing spatter and sparks.

6. Electric resistance welding

It refers to a group of welding processes such as spot and seam welding that produce coalescence of faying surfaces where heat to form the weld is generated by the electrical resistance of material combined with the time and the force used to hold the materials together during welding.

Advantages of welded joints over riveted joints

They are lighter
Cost of welded joint is lower
They are tight and leak proof
Their production time is less
There is no problem of stress concentration
It has good appearance
Their strength is high
It is easy to do in many parts which is difficult to riveting

Advantages of welded structures over cast iron structures

Below are some advantages of welding

They are lighter in weight
It offers more flexibility
Its machining is easy
Capital investment is lower

Disadvantages of welded joints

Below are some disadvantages of welding

Their capacity to damp vibrations is poor
Parts manufactured by It are prone to thermal distortion due to heat generated
Quality of parts manufactured depends on skills of operator
Inspection of welded joints is costly and requires specialist

Defects in welding

Incomplete filling of weld metal into the groove
Lack of fusion of weld metal and surface
Slag inclusion in welding
Cracks in the welded surface
Porous weld surface
Excessively convex weld
Spatter in the workpiece surface
Undercut in the weld surface
Overlap in weld surface

Featured Image Source: By Weldscientist – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=95107351