report
write a report about the five questions attached
WELDING TECHNOLOGY
Dr. S.Thiru PhD.,
ENME 102Full Lectures
Mechanical engineering department
Copyright © 2020 University of Jeddah
http://www.uj.edu.sa/Home.aspx
CONTENTS
Copyright © 2020 University of Jeddah
➢ Fundamentals of Welding.
➢ Safety and Health of Welders.
➢ Arc Welding with a Consumable Electrode.
➢ Electrodes and Filler Materials.
Introductions
Copyright © 2020 University of Jeddah
Reasons for and benefits of joining (by design goals)
Achieve functionality
Facilitate manufacturability
Minimize costs
Allow complex shapes to be formed
joining Processes and Equipment
Overview:
Joining processes fall into three major categories：
1. Welding
2. Adhesive bonding
3. Mechanical fastening
Welding processes, classified into three basic
categories:
1. Fusion welding
2. Solid-state welding
3. Brazing and soldering.
Copyright © 2020 University of Jeddah
AWS Master chart of welding and allied
processes
Copyright © 2020 University of Jeddah
Major categories
Allied processes, which use
similar energy sources
AWS designation
AMERICAN WELDING SOCIETY
Welding Processes Listed by Energy Source
Copyright © 2020 University of Jeddah
Electric Arc Fusion Welding
Copyright © 2020 University of Jeddah
Arc welding
▪ For workpieces that are electrical conductors, it can be made part of the
electric circuit with an electric power supply.
▪ As part of the electric circuit, electric current is passed to the conductive
workpiece through an arc from an electrode across a gap in a gas
Resistance welding
If the electric current can be passed directly through the workpiece as an integral
part of the circuit.
High Energy beam welding
A beam of intense, high-density electrons are applied to heat a workpiece
(whether an electrical conductor or not).
Advantages and Disadvantages of Welding
Copyright © 2020 University of Jeddah
Advantages
Joints are permanent,
precluding accidental (or even
intentional) disassembly and
loosening
Wide variety of process
embodiments
Applicability to many materials
within fundamental class
Allows manual or automated
operation
Can be portable
Reasonable overall cost, usually
Provides leak tightness with
continuous welds
Disadvantages
Prevents/precludes disassembly for any
purpose
Heat of some welding (especially
involving fusion) disrupts base material
properties
Precludes joining between materials
from different classes
Unbalanced heat input leads to
distortion or residual stresses
Requires considerable operator skill
Can be expensive due to skilled labor
rates or due to labor intensity for
thick, long, or critical welds
Capital equipment can be expensive,
especially for some automated
processes
Modes of Arc Welding
Copyright © 2020 University of Jeddah
Direct current straight polarity (DCSP): Arc heating when the
workpiece is positive and the welding electrode is negative.
Also called as dc electrode negative (EN) or dc-.
Direct current reverse polarity (DCRP): Arc heating when the
workpiece is negative and the welding electrode is positive.
Also called as dc electrode positive (EP) or dc+.
AC mode: One-half of the voltage cycle operates as dc-/DCSP,
while the other half operates as dc+/DCRP.
Arc Welding Processes
Copyright © 2020 University of Jeddah
Nonconsumable Electrode Arc Welding
Gas tungsten arc welding (GTAW)
Plasma arc welding (PAW)
Stud arc or simply stud welding (SW)
Magnetically-impelled arc butt welding
(MIAB)
Consumable Electrode Arc Welding
Processes
Shielded metal arc welding (SMAW)
Flux-cored arc welding (FCAW)
Gas metal arc welding (GMAW)
Submerged arc welding (SAW)
Electrogas welding (EGW)
Electroslag welding (ESW)
GTAW PAW
SMAW FCAWSAW
https://www.youtube.com/watch?v=jRmqrqIGOIY
https://www.youtube.com/watch?v=QMFDpZwbPwg
CODES, STANDARDS AND PRACTICE
Copyright © 2020 University of Jeddah
American Welding Society
The AWS multi-volume Welding Handbook is a comprehensive treatment of
the art and technology of welding [AWS].
It includes:
Volume 1 – Fundamentals of Welding
Volumes 2 and 3 – Welding Processes
Volume 4 – Engineering Applications – Materials
Volume 5 – Engineering Applications – Design
The welding of structural (non-pressure boundary) members typically
complies with either AWS D l.l or AWS D1.6. The American Welding
Society
(AWS) standards of interest to welding piping and pipelines include:
AWS A 3.0 – Welding terms and definitions, including terms for brazing, soldering,
thermal spraying and thermal cutting.
AWS A 5.01 – Filler metal procurement guidelines.
AWS A 5.XX – Series of filler metal specifications.
AWS Dl.l – Structural welding code – steel.
General Requirements
Copyright © 2020 University of Jeddah
Welder’s protective clothing
General Requirements
Copyright © 2020 University of Jeddah
Minimum warning label for Arc welding processes and equipment
Protection in the general area
Copyright © 2020 University of Jeddah
Protective screens
Persons adjacent to welding and cutting must be
protected from radiation and hot spatter by flame
resistant shields or screens with suitable eye and face
protection clothing.
Wall reflectivity
Where arc welding or cutting is regularly carried out
adjacent to painted walls, the walls should be painted
with low reflective pigments for UV radiation such as
Titanium dioxide or Zinc oxide.
Fire
Open flames, electric arcs, spatter, hot metal and sparks
are the potential fire igniting elements related to
welding.
The risk of fire is greatly increased by combustible floor,
partitions, ceiling etc and also by the presence of
combustibles in the working area such as wood, paper,
trash, cotton, textiles, chemicals, paints, and flammable
liquids and gases. For outdoor, dry grass and brushes
highly ignite potential to welding.