Electric arc welding uses heat from an electric arc to join metal surfaces. It is a manual process that uses a consumable electrode coated in flux. An electric current forms an arc between the electrode and the metals, melting them together. As the weld is laid down, the flux coating decomposes and provides a protective gas atmosphere and slag layer. Arc welding is widely used in construction, fabrication, and repair due to its versatility, portable equipment, and ease of use.
This slide is for mechanical engineering student. this is basically describes about the arc welding and its types with processes and also its advantages and disadvantages..... Remember us in your Prayers Folks.
Spot welding (or resistance spot welding[1]) is a type of electric resistance welding used to weld various sheet metal products, through a process in which contacting metal surface points are joined by the heat obtained from resistance to electric current.
The process uses two shaped copper alloy electrodes to concentrate welding current into a small "spot" and to simultaneously clamp the sheets together. Work-pieces are held together under pressure exerted by electrodes.
Seam welding is a welding technique in which two similar or dissimilar metals are connected by supplying an electric current and in this process a nugget formation takes place. Mostly, these nuggets are formed in the form of a butt or overlapping welding components. Do you know the meaning of these nuggets? Well, the nuggets are nothing but small pools of molten metal which are formed at the location with high electrical resistance. Seam welding is one of the types of Resistance welding.
Seam welding is a welding technique in which two similar or dissimilar metals are connected by supplying an electric current and in this process a nugget formation takes place. Mostly, these nuggets are formed in the form of a butt or overlapping welding components. Do you know the meaning of these nuggets? Well, the nuggets are nothing but small pools of molten metal which are formed at the location with high electrical resistance. Seam welding is one of the types of Resistance welding. Spot welding and seam welding are two of the most commonly used welding processes in the manufacturing industry. Spot welding is a process that uses heat and pressure to join two metal pieces together. It applies an electric current between two electrodes, creating an electrical arc that melts the metal at the point of contact. Seam welding is a similar process. But instead of using two electrodes, it involves running a continuous wire along the seam of two metal pieces to join them together. Both are used in automotive and aerospace manufacturing for joining sheet metal components.Spot welding is better utilized for welding materials that’re smaller and are overlapping. Spot welding has a manual mode while seam welding does not. Seam welding is great for welds that need an air-tight seal (remember that spot welds tend to not be the best overall. It’s also great for welds that must be continually done such as for placing strings of spot welds. What are the best uses for spot vs. seam welding? Spot welding is ideal for joining thin sheets of metal. Making it ideal for light duty applications including electronics and battery manufacturing. It is also widely used in the automotive sector, due to it’s ease of automation in high-volume production lines.
While seam welding is best suited for joining thicker materials, or creating a continuous weld along a seam. Thus making it ideal for the fabrication of tanks and vessels, as well other pipe and tube welding applications.
Spot and seam welding are both important met
This slide is for mechanical engineering student. this is basically describes about the arc welding and its types with processes and also its advantages and disadvantages..... Remember us in your Prayers Folks.
Spot welding (or resistance spot welding[1]) is a type of electric resistance welding used to weld various sheet metal products, through a process in which contacting metal surface points are joined by the heat obtained from resistance to electric current.
The process uses two shaped copper alloy electrodes to concentrate welding current into a small "spot" and to simultaneously clamp the sheets together. Work-pieces are held together under pressure exerted by electrodes.
Seam welding is a welding technique in which two similar or dissimilar metals are connected by supplying an electric current and in this process a nugget formation takes place. Mostly, these nuggets are formed in the form of a butt or overlapping welding components. Do you know the meaning of these nuggets? Well, the nuggets are nothing but small pools of molten metal which are formed at the location with high electrical resistance. Seam welding is one of the types of Resistance welding.
Seam welding is a welding technique in which two similar or dissimilar metals are connected by supplying an electric current and in this process a nugget formation takes place. Mostly, these nuggets are formed in the form of a butt or overlapping welding components. Do you know the meaning of these nuggets? Well, the nuggets are nothing but small pools of molten metal which are formed at the location with high electrical resistance. Seam welding is one of the types of Resistance welding. Spot welding and seam welding are two of the most commonly used welding processes in the manufacturing industry. Spot welding is a process that uses heat and pressure to join two metal pieces together. It applies an electric current between two electrodes, creating an electrical arc that melts the metal at the point of contact. Seam welding is a similar process. But instead of using two electrodes, it involves running a continuous wire along the seam of two metal pieces to join them together. Both are used in automotive and aerospace manufacturing for joining sheet metal components.Spot welding is better utilized for welding materials that’re smaller and are overlapping. Spot welding has a manual mode while seam welding does not. Seam welding is great for welds that need an air-tight seal (remember that spot welds tend to not be the best overall. It’s also great for welds that must be continually done such as for placing strings of spot welds. What are the best uses for spot vs. seam welding? Spot welding is ideal for joining thin sheets of metal. Making it ideal for light duty applications including electronics and battery manufacturing. It is also widely used in the automotive sector, due to it’s ease of automation in high-volume production lines.
While seam welding is best suited for joining thicker materials, or creating a continuous weld along a seam. Thus making it ideal for the fabrication of tanks and vessels, as well other pipe and tube welding applications.
Spot and seam welding are both important met
Welding Processes
Two Categories of Welding Processes
Arc Welding
Resistance Welding
Oxy-fuel Gas Welding
Other Fusion Welding Processes
Solid State Welding
Shielded Metal Arc Welding
Gas Metal Arc Welding
Flux‑Cored Arc Welding
Electro gas Welding
Submerged Arc Welding
Gas Tungsten Arc Welding (GTAW) or TIG
Resistant Welding
Brazing and Soldering
An electric vehicle, also called an EV, uses one or more electric motors or traction motors
for propulsion instead of the traditional fossil fuel.
• First electric carriage was built in 1830s and the first electric automobile was built in 1891
in the United States.
• Types : Battery electric Vehicle
Hybrid Electric Vehicle
Plug-in Hybrid Electric Vehicle
Fuel Cell Electric Vehicle
• Electric vehicles will play a pivot role in changing the environment and economy around
the globe in the next two decades.
Demand of welding increase of new materials.
-- ceramics and metal matrix composites.
-- High strength low-alloy (HSLA) steels
Lack of skilled labours
Traditional welding techniques are costly
Safety concerns.
Need to improve the total cost effectiveness of the welding
Lalit Yadav
power systems ppt on Arc welding and Electric welding equipment and compariso...sanjay kumar pediredla
this ppt is mainly based on the power systems related topic and in this ppt mainly consists of ac and dc weldings and which welding is used mainly and the importance of arc welding and electric welding and the techniques are also discussed in this and it is so helpful .and the safety requirements and the equipment used is also discussed in this topic
Welding Processes
Two Categories of Welding Processes
Arc Welding
Resistance Welding
Oxy-fuel Gas Welding
Other Fusion Welding Processes
Solid State Welding
Shielded Metal Arc Welding
Gas Metal Arc Welding
Flux‑Cored Arc Welding
Electro gas Welding
Submerged Arc Welding
Gas Tungsten Arc Welding (GTAW) or TIG
Resistant Welding
Brazing and Soldering
An electric vehicle, also called an EV, uses one or more electric motors or traction motors
for propulsion instead of the traditional fossil fuel.
• First electric carriage was built in 1830s and the first electric automobile was built in 1891
in the United States.
• Types : Battery electric Vehicle
Hybrid Electric Vehicle
Plug-in Hybrid Electric Vehicle
Fuel Cell Electric Vehicle
• Electric vehicles will play a pivot role in changing the environment and economy around
the globe in the next two decades.
Demand of welding increase of new materials.
-- ceramics and metal matrix composites.
-- High strength low-alloy (HSLA) steels
Lack of skilled labours
Traditional welding techniques are costly
Safety concerns.
Need to improve the total cost effectiveness of the welding
Lalit Yadav
power systems ppt on Arc welding and Electric welding equipment and compariso...sanjay kumar pediredla
this ppt is mainly based on the power systems related topic and in this ppt mainly consists of ac and dc weldings and which welding is used mainly and the importance of arc welding and electric welding and the techniques are also discussed in this and it is so helpful .and the safety requirements and the equipment used is also discussed in this topic
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
1. ELECTRIC ARC WELDING
The welding in which the electric arc is produced
to give heat for the purpose of joining two
surfaces is called electric arc welding.
The joining by fusing of two or more pieces of
metal together by using the heat produced
from an electric arc .
2. How an arc is formed?
• The arc is like a flame of
intense heat that is
generated as the
electrical current passes
through a highly
resistant air gap.
4. Arc Welding
• It is a fusion welding processes which uses an
electric arc to produce the heat required for
melting the metal.
• The welder creates an electric arc that melts the base metals
and filler metal (consumable) together so that they all fuse
into one solid piece of metal
5. Arc Welding
• Many things around us are welded …
– Pipelines that bring fresh water
– Towers that carry electricity to houses
– Cars and buses that take people where they need to go
• Arc welding continues to be used extensively in the construction of
steel structures and in industrial fabrication.
• The process is used primarily to weld iron and steels (including
stainless steel) but aluminium, nickel and copper alloys can also be
welded with this method.
• It dominates other welding processes in the maintenance and
repair industry, and though flux-cored arc welding is growing in
popularity
• Is popular because it can be used in the field without
complicated equipment and gases
6. Arc Welding
• It is a manual arc welding process that uses a
consumable electrode coated in flux to lay the weld.
• An electric current, in the form of either alternating
current or direct current from a welding power supply,
is used to form an electric arc between the electrode
and the metals to be joined.
• As the weld is laid, the flux coating of the electrode
disintegrates, giving off vapors that serve as a shielding
gas and providing a layer of slag, both of which protect
the weld area from atmospheric contamination.
7. Arc Welding
• Arc welding is a process that melts and joins metals by
heating them with an arc established between a sticklike
covered electrode and the metals.
• The core wire conducts the electric current to the arc and
provides filler metal for the joint.
• The electrode holder is essentially a metal clamp with an
electrically insulated outside shell for the welder to hold
safely.
• The heat of the arc melts the core wire and the flux
covering at the electrode tip into metal droplets.
• Molten metal in the weld pool solidifies into the weld metal
while the lighter molten flux floats on the top surface and
solidifies as a slag layer.
9. Arc Welding
• Also known as “stick welding”
• Uses an arc between a covered electrode
and a workpiece
• Shielding is obtained from decomposition
of the electrode cover
• Pressure is not used
• Filler metal is obtained from the electrode
10. Principle of Arc
• A suitable gap is kept between the work and
electrode
• A high current is passed through the circuit.
• The electric energy is converted into heat
energy, producing a temperature of 3000°C to
4000°C.
• This heat melts the edges to be welded and
molten pool is formed.
• On solidification the welding joint is obtained
11. Arc Welding
• Process:
– Intense heat at the arc melts the tip of the electrode
– Tiny drops of metal enter the arc stream and are deposited
on the parent metal
– As molten metal is deposited, a slag forms over the bead
which serves as an insulation against air contaminants
during cooling
– After a weld ‘pass’ is allowed the cool, the oxide layer is
removed by a chipping hammer and then cleaned with a
wirebrush before the next pass.
12. Arc Welding
• Because of the versatility of the process and
the simplicity of its equipment and
operation, shielded metal arc welding is one
of the world's most popular welding
processes.
13. Basics of Arc Welding
• The arc is struck between the electrode
and the metal.
• It then heats the metal to the melting
point.
• The electrode is then removed, breaking
the arc between the electrode and the
metal. This allows the molten metal to
“freeze” or solidify.
18. Basic Steps of Arc Welding
• Prepare the base materials: remove paint and
rust
• Choose the right welding process
• Choose the right filler material
• Assess and comply with safety requirements
• Use proper welding techniques and be sure to
protect the molten puddle from contaminants in
the air
• Inspect the weld
19. ARC WELDING
• An electric arc is generated between an
electrode and the parent metal
• The electrode carries the electric current to
form the arc, produces a gas to control the
atmosphere and provides filler metal for the
weld bead
• Electric current may be AC or DC.
20. Electric Power for Welding
• Current used may be
– 1. AC
– 2. DC
For most purposes, DC is preferred.
21. AC Arc Welding
• instead of 220 V at 50 A, for example, the
power supplied by the transformer is around
17–45 V at currents up to 600 A.
22. DC Arc Welding
• D.C. machines are made up to the capacity range
of 600 amperes.
• 45 to 95 volts
• D.C. can be given in two ways:
(a) Straight polarity
(b) Reverse polarity
The polarity will affect the weld size and application
23. Comparison of A.C. and D.C. arc welding
Direct Current (from Generator)
1. Less efficiency
2. Power consumption more
3. Cost of equipment is more
4. Low voltage – safer operation
5. Suitable for both ferrous non ferrous metals
6. Preferred for welding thin sections
7. Positive terminal connected to the work
8. Negative terminal connected to the electrode
27. Arc Welding
• The choice of electrode for SMAW depends on
a number of factors, including
1. The weld material
2. Welding position and
3. The desired weld properties.
28. Welding Electrodes
• The composition of the electrode core is generally similar and
sometimes identical to that of the base material.
• But even though a number of feasible options exist, a slight
difference in alloy composition can strongly impact the properties
of the resulting weld. This is especially true of alloy steels such as
HSLA steels.
• Likewise, electrodes of compositions similar to those of the base
materials are often used for welding nonferrous materials like
aluminium and copper.
• However, sometimes it is desirable to use electrodes with core
materials significantly different from the base material. For
example, stainless steel electrodes are sometimes used to weld two
pieces of carbon steel, and are often utilized to weld stainless steel
workpieces with carbon steel workpieces.
29. Coated Electrodes
• The electrode is coated in a metal mixture
called flux, which gives off gases as it
decomposes to prevent
1. Weld contamination
2. Introduces deoxidizers to purify the weld
3. Causes weld-protecting slag to form
4. Improves the arc stability, and
5.Provides alloying elements to improve the weld
quality.
30. Electrode Coating
• Electrode coatings can consist of a number of different
compounds, including rutile, calcium fluoride, cellulose, and iron powder.
• Rutile electrodes, coated with 25%–45% TiO2, are characterized by ease of
use and good appearance of the resulting weld. However, they create
welds with high hydrogen content, encouraging embrittlement and
cracking.
• Electrodes containing calcium fluoride (CaF2), sometimes known as basic
or low-hydrogen electrodes, are hygroscopic and must be stored in dry
conditions. They produce strong welds, but with a coarse and convex-
shaped joint surface.
• Electrodes coated with cellulose, especially when combined with
rutile, provide deep weld penetration, but because of their high moisture
content, special procedures must be used to prevent excessive risk of
cracking.
• Finally, iron powder is a common coating additive, as it improves the
productivity of the electrode, sometimes as much as doubling the yield.
31. Functions of electrode (flux) covering
• Provides the gaseous shield to protect the
molten metal from air.
– Cellulose-type electrode (C6H10O5)x , providing
gas mixture of H2, CO, H2O and CO2.
– Limestone-type electrode (CaCO3) – low in
hydrogen and it is used for welding metals that
are susceptible to hydrogen cracking such as high-
strength steels.
32. Functions of electrode (flux) covering
• Deoxidation - Provide deoxidizers and fluxing agent to
deoxidize and cleanse the weld metal. The solid slag
also protects the weld metal from oxidation.
• Arc stabilization - Provide arc stabilizers which are
compounds such as potassium oxalate and lithium
carbonate. They readily decompose into ions in an
arc, which increase electrical conductivity.
• Metal addition - Provide alloying elements (for
composition control) and metal powder (increase
deposition rate) to the weld pool.
33. Types of Electrodes
Electrodes can be divided into three groups—
1. Fast-fill electrodes,
Fast-fill electrodes are designed to melt quickly so
that the welding speed can be maximized
2. Fast-freeze electrodes,
fast-freeze electrodes supply filler metal that
solidifies quickly, making welding in a variety of
positions possible by preventing the weld pool from
shifting significantly before solidifying. and
3.Intermediate electrodes go by the name "fill-freeze"
or "fast-follow" electrodes.
34. Arc Welding Power Supplies
• The current for arc welder can be supplied by
line current or by an alternator/generator.
– The amount of heat is determined by the current flow (amps)
– The ease of starting and harshness of the arc is determined by the electrical
potential (volts).
• Welding current adjustments can include:
– Amperage
– Voltage
– Polarity
– High frequency current
– Wave form
35. Amperage Output
• The maximum output of the power supply
determines the thickness of metal that can be
welded before joint beveling is required.
• 185 to 225 amps is a common size.
• For an individual weld, the optimum output
amperage is determined by
– thickness of the metal
– type of joint and
– type of electrode
36. Five Common Output Currents
For Arc Welding
1. AC (Alternating Current)
2. DC (Direct Current)
3. ACHF (Alternating Current-High Frequency)
4. PC (Pulsed Current)
5. Square wave
37. Alternating Current
• Alternating current: The type of current where
the flow of electrons reverses direction
(polarity) at regular intervals.
• Recommended for general purpose electrodes
and flat position.
39. Direct Current
• Direct current: The type of current where the flow of
electrons (polarity) is in one direction.
• Controlling the polarity allows the welder to influence the
location of the heat.
• When the electrode is positive (+) DCRP, it will be slightly
hotter than the base metal.
• When the base metal is positive (+), DCSP, the base metal
will be slightly hotter than the electrode.
• DC is required for GMAW
• It is frequently used for SMAW
40. Ampere
• Electricity passing through a resistance causes
heat.
• An air gap is a high resistance
• The greater the amperage flowing through the
resistance (air gap) the greater the heat.
• The electrode also has resistance.
• Excessive amperage for the diameter of the
electrode (current density) over heats the
electrode.
• Insufficient amperage for the diameter of
electrode makes the electrode hard to start.
42. Arc Welding Defects
The most common quality problems associated with SMAW include
• 1. Weld spatter
Weld spatter, while not affecting the integrity of the weld, damages
its appearance and increases cleaning costs. It can be caused by
excessively high current, a long arc, or arc blow, a condition
associated with direct current characterized by the electric arc
being deflected away from the weld pool by magnetic forces. Arc
blow can also cause porosity in the weld, as can joint
contamination, high welding speed, and a long welding arc,
especially when low-hydrogen electrodes are used.
• 2. Porosity
Porosity, often not visible without the use of advanced
nondestructive testing methods, is a serious concern because it can
potentially weaken the weld.
43. Arc Welding Defects
• 3. Poor fusion
Another defect affecting the strength of the weld is poor
fusion, though it is often easily visible. It is caused by low
current, contaminated joint surfaces, or the use of an improper
electrode.
• 4. Shallow penetration
Shallow penetration, another detriment to weld strength, can be
addressed by decreasing welding speed, increasing the current or
using a smaller electrode.
• 5. Cracking.
Any of these weld-strength-related defects can make the weld
prone to cracking, but other factors are involved as well. High
carbon, alloy or sulfur content in the base material can lead to
cracking, especially if low-hydrogen electrodes and preheating are
not employed. Furthermore, the workpieces should not be
excessively restrained, as this introduces residual stresses into the
weld and can cause cracking as the weld cools and contracts.[10]
44. Advantages of arc welding
• 1. Simple welding equipment
• 2. Portable
• 3. Inexpensive power source
• 4. Relatively inexpensive equipment
• 5. Welders use standard domestic current.
• 6. Process is fast and reliable
• 7. Short learning curve
• 8. Equipment can be used for multiple functions
• 9. Electric arc is about 5,000 oC
• 10. Used for maintenance, repair, and field construction
45. Disadvantages
• Not clean enough for reactive metals such as
aluminium and titanium.
• The deposition rate is limited because the
electrode covering tends to overheat and fall
off.
• The electrode length is ~ 35 mm and requires
electrode changing lower the overall
production rate.
46. Flux-Cored Arc Welding (FCAW)
• Uses an arc between a continuous filler
metal electrode and a workpiece
• Shielding is provided by a flux contained
within the electrode
• Additional shielding may be obtained from
an externally supplied gas or gas mixture
• Commonly used in construction because it
is a fast welding process and is easily
portable