Lab Report 1
WELDING AND ITS TYPES
Introduction to Metallurgy and Materials Engineering
(MME-101L)
(Session 2023 – 27)
Submitted By: Person 1 (Regd. No.) 2023 MM 06
Person 2 (Regd. No.) 2023 MM 21
Submitted To: Muhammad Arshad
Department of Metallurgical and Materials Engineering
UNIVERSITY OF ENGINEERING AND TECHNOLOGY, LAHORE
WELDING AND ITS TYPES
Introduction:
Welding is a process which involves joining of materials by
means of heat, pressure or both forming a join as the parts cools. These materials
are usually metals and thermoplastics. Welding is mostly done by melting and by
adding a filter material that cools to become a strong joint. There are many types
of welding at present. They are different on the principle of their working. Their
names are given below:
1. Submerged Arc Welding
2. Shielded Metal Arc Welding
3. Friction Welding
4. Gas Tungsten Welding
5. Oxy Fuel Welding
Submerged Arc Welding:
It is a wielding process which involves the
formation of a molten weld pool beneath a layer of flux material. The arc is
submerged beneath a layer of flux because it acts as a blanket and protects it from
the atmosphere contamination.
Equipment:
It consists of two
materials welding flux and consumable
electrode wire.
Fig 1 Submerged Arc Welding
Source of Heating:
The source of heating for Submerged Arc Welding is constant
current power source.
Significance:
It is very useful for welding thick materials and can deposit large amount of
weld metal quickly.
The process is suitable for both indoor and outdoor work.
In it 50 to 90% of the flux can be recovered and recycled and reuse. (1)
It helps the operator to see the weld pool clearly.
Limitations:
It is limited to the large number of spaces around the joint to be welded. It
cannot be use in tight spaces.
It is very costly because the equipment used are very expensive.
It is limited to high thickness materials. (2)
The flux and slag residue are hazardous and can present a health and safety
concern.
Shielded Arc Welding:
It is also known as manual arc welding, flux shielded
welding and informally as “Stick Welding”. (3) It is a process in which the electrode
is coated with flux to lay the weld. The heat which is generated by arc melts both
the electrode and the workpiece to create a weld
which solidifies to make a strong joint.
Equipment:
It consists of an electrode with an
electrode holder, a ground clamp and welding
cables connecting the two.
Fig 2 Shielded metal arc welding
Source of Heating:
The source of heating for shielded arc welding is constant
current power source.
Significance:
It is used to weld a variety of metals, including stainless steel
and cast iron etc.
It is very cheap and is easily affordable making it accessible to
a wide range of users.
It is simple to use making it suitable for beginners and
experienced welders alike
When it is performed correctly, it can produce strong and
durable welds.
Limitations:
It requires frequent electrode changes.
It also produces high level of fumes and smoke which when inhaled is
harmful to welders’ health.
It requires a high level of skill and training to produce high quality welds.
It is a slower process which results in low productivity.
Friction Welding:
It is a solid-state welding
process for joining workpieces by generating
heat through mechanical friction. In this
process no melting occurs. It uses the principle
of heat generation by friction between two
surfaces.
Equipment: It is used with metals and
thermoplastics because the purpose is to
produce friction so no other materials are needed. Fig 3 Friction Welding
Source of Heating:
They do not use any external heat source to melt because
the welding is formed by applying external pressure.
Significance:
It creates strong and high-quality bonds between materials. It is also used
to join dissimilar materials.
It is a fast process and does not require filler materials and thus increasing
its efficiency.
It is environmentally friendly because it produces fewer emissions.
It is a cost-effective way to produce new parts.
Limitations:
It is not suitable for large objects.
Friction welding machines are very expensive and hard to maintain making
it less accessible for small operations.
It is not suitable for sensitive materials.
It only uses round bars of same cross section.
References:
(1) Resources Recovered Calculation Weld Engineering Co. Retrieved 5 March
2015
(2) Cost Evaluation and Life Cycle Assessment of Thick plates using SWAD AND
GMAW
(3) Houldcroft P.T. (1973) Chapter 3 Flux Shielded Arc Welding. Welding process.
Cambridge University Press. Page 23.
