This document discusses gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding. It describes the key components and working principles of the TIG welding process, including the use of a non-consumable tungsten electrode to generate an arc, an inert shielding gas to protect the weld area, and optional filler metals. The document also outlines typical applications of TIG welding in industries like aerospace, as well as advantages such as high quality welds and control, and disadvantages including higher costs and need for skilled welders.

1. Prepared by: Taimoor Hassan
Batch: 2016
Roll No: D-16MME-43

2. INTRODUCTION
Gas tungsten arc welding (GTAW), also known as tungsten inert gas
(TIG) welding.
 An arc welding process that uses a non-consumable tungsten
electrode to produce the weld.
The weld area is protected from atmospheric contamination by an
inert shielding gas (argon or helium).
A filler metal is normally used.
The GTAW process is versatile and can be used on ferrous and
nonferrous metals
Gas tungsten arc welding uses a constant current power source

3. OPERATION

4. WORKING PRINCIPLE
An arc is established between the end of a tungsten electrode and
The electrode is not melted and the welder keeps the arc gap
constant.
 The current is controlled by the power-supply unit.
A filler metal, usually available in 1 m lengths of wire, can be added
to the leading edge of the pool as required.
The molten pool is shielded by an inert gas which replaces the air in
the arc area.
Argon and helium are the most commonly used shielding gases.

5. WORKING PRINCIPLE
The fixed welding variables include the type of filler metal, electrode
type and size, the type of current, and the type of shielding gas.
 The process can be used to weld thin or thick materials with or
without a filler metal.
When welding thinner materials, edge joints, and flange, filler metals
are not used.
For thicker materials, an externally fed filler wire is generally used.
The size of the filler metal wire depends on the thickness of the base
metal

6. TUNGSTEN
ELECTRODE
Create the arc for TIG welding.
Tungsten properties allows an
arc to maintain a temp up to
6100oC.
Electrode diameter is vary 1/16
to ¼ of an inch.
Most critical component of the
process is shape of the tip of the
electrode.
Pointed tip – welding ferrous
metals.
Rounded and Tapered ball end –
welding non-ferrous metals.

7. SHIELDING GASES
Argon and helium are the two most commonly used shielding gases
used for GTAW.
The characteristics most desirable for shielding purposes are the
chemical inertness of the gases and their ability to produce smooth
arc action at high currents.
They protect the tungsten electrode and the molten weld pool from
the atmosphere.
Gas purity affects a weld for the best results the percent of inert gas
used should be at least 99.9 percent pure
Argon and hydrogen mixtures are often used for welding of stainless
steel

8. APPLICATION
Gas tungsten arc welding is most commonly used to weld stainless
steel and nonferrous materials, such as aluminium and magnesium
Aerospace Industries uses lite metals (aluminium and its alloy) thin
sheet and need high quality welding so TIG is more suitable for it
Use in nuclear plants

9. ADVANTAGES
GTAW can be used for welding on almost any type of metals.
GTAW allows the welder to maintain a higher degree of control over
the welding pool.
GTAW gives extremely high quality results under the right
conditions.
GTAW results in little-to-no spatter, making it the one of the
cleanest welding processes
GTAW can be performed with or without filler metals
GTAW allows for good control over variables such as temperature.
Creates strong joints.

10. DISADVANTAGES
GTAW often has higher costs.
GTAW requires a highly skilled, experienced welder to perform.
GTAW has lower deposition rates when compared to some other
welding processes.
Lower melting point material can not weld by this method
GTAW slower welding speed
Not easily portable.