MetFab - Air Products Welder's Handbook - Flipbook - Page 6
Introduction
Welding basics
Welding by fusion requires localised
melting of the components to be joined.
The melted materials mix in the weld
pool which solidifies forming a weld.
The molten metal and surrounding area
must be protected from the atmosphere.
This is commonly achieved using a weld
process gas or flux (see examples below).
Two widely used heat sources are:
Metal inert gas
Electric arc
Electrode
Arc
High current
low voltage
supply
Weld
process gas
Weld
Parent metal
Gas flame
Fuel gas flame
Blow pipe
In metal inert gas (MIG) welding, a weld
process gas is used.
Manual metal arc welding
The strength of the welded joint should be
greater than, or equal to, the strength of
the parent material. Quality is paramount.
Flux coating
Solid wire core
Slag
Protective
gas
Weld
Parent metal
In manual metal arc (MMA) welding,
a flux is used to generate a protective
gas and slag.
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