Welding | Definition, Types, Advantages, Disadvantages

By | June 2, 2018

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.

Joints obtained by It 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

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

Disadvantages of welded joints

  • 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

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