Welding is a process in which localized coalescence (permanent joint) is produced by heating the material upto suitable temperature with or without application of filler material.
If the filler material is of same material as base material then the welding is Homogeneous welding, if filler material is different from the base material then the welding is Heterogeneous welding.
Advantages of Welding:-
- Different material cab be welded.
- Welding can be done anywhere.
Disadvantages of Welding:-
- In the heat affected zone properties of base material is also affected.
- To dismantle, we have break the weld.
- Initial investment is more.
- Highly skilled oprtor required.
It is the material support provided at the root side of a weld to aid in the control of penetration.
The metal to be joined or cut is termed the base metal.
Bead or Weld Bead:-
Bead is the metal added during a single pass of welding. The bead appears as a separate material from the base metal.
In arc welding, a crater is despression in weld-metal pool at point where the arc strikes the base metal plate.
The rate at which the weld-metal is deposited per unit time is the deposition rate and is normally expressed as kg/h.
The metal fused into the corner of a joint made of two pieces placed at approximately 90o to each other is termed fillet weld.
It is the depth upto which the weld metal combines with the base metal as measured from the top surface of the joint.
The portion of the weld joint that is melted by the heat of welding is called puddle.
It is the point at which the two pieces to be joined by welding are nearest.
A small weld generally used to temporarily hold the two pieces together during actual welding is the tack weld.
Toe of weld:-
It is the junction between the weld face and the base metal.
In gas welding, torch mixes the fuel and oxygen and controls its delivery to get the desired flames.
It is the exposed surface of weld.
The metal that is solidified in the joint is called weld metal. It may be only a base metal or a mixture of base metal and filler metal.
A single movement of the welding torch or electrode along the length of the joint which results in a bead is weld pass.