The objective of this subject is to develop a practical understanding of welding with regard to welding processes, and auxiliary welding equipment for the welder. Also, to develop a technical understanding of the information contained on engineering drawings and the use of the information to communicate setup and welding instructions from the designer to the welder and fitter.This subject is very important for engineering as well as diploma in Mechanical Engineering department students.I hope you will get some ideas about welding technology.
Welding process
Arc Welding
Resistance Welding
Oxy fuel Gas Welding
Other Fusion Welding Processes
Solid State Welding
Weld Quality
Weld ability
Design Considerations in Welding
Welding process
Arc Welding
Resistance Welding
Oxy fuel Gas Welding
Other Fusion Welding Processes
Solid State Welding
Weld Quality
Weld ability
Design Considerations in Welding
This presentation is for mechanical engineering/ civil engineering students to help them understand the different type of destructive mechanical testing of materials. The tensile testing, hardness, impact test procedures are explained in detail.
Electron Beam Welding is a fusion welding process in which a beam of high-velocity electrons is applied to the material to be joined. The work-piece melt as the kinetic energy of the electrons is transformed into heat upon impact. The EBW process is well-positioned to provide industries with highest quality welds and machine designs that have proven to be adaptable to specific welding tasks and production environments.
this ppt pdf beneficial for 1st year engineering student who studying workshop technology. in this pdf types of joining, gas welding, arc welding, spot welding, tig welding, mig welding, soldering brazing and different welding defect has been discussed.
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
FRICTION STIR WELDING is a very latest tchnology of welding process .Its a green method of solid state joining, and also a defect free method .
To know more about this you can also watch this animation https://youtu.be/kEEST5cgOao
One of the welding processes that used in Engineering field is the resistance welding. There are several types of welding processes similar to this, but resistance welding has its unique features.
Thanks for the colleagues who give this slides to publish.
This presentation is for mechanical engineering/ civil engineering students to help them understand the different type of destructive mechanical testing of materials. The tensile testing, hardness, impact test procedures are explained in detail.
Electron Beam Welding is a fusion welding process in which a beam of high-velocity electrons is applied to the material to be joined. The work-piece melt as the kinetic energy of the electrons is transformed into heat upon impact. The EBW process is well-positioned to provide industries with highest quality welds and machine designs that have proven to be adaptable to specific welding tasks and production environments.
this ppt pdf beneficial for 1st year engineering student who studying workshop technology. in this pdf types of joining, gas welding, arc welding, spot welding, tig welding, mig welding, soldering brazing and different welding defect has been discussed.
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
FRICTION STIR WELDING is a very latest tchnology of welding process .Its a green method of solid state joining, and also a defect free method .
To know more about this you can also watch this animation https://youtu.be/kEEST5cgOao
One of the welding processes that used in Engineering field is the resistance welding. There are several types of welding processes similar to this, but resistance welding has its unique features.
Thanks for the colleagues who give this slides to publish.
Underwater Cutting & Welding Manual U.S. Navystickweld
The United States Navy Guide to Underwater Welding and Cutting. A very good overview of the basic procedures and equipment used when welding and cutting underwater.
Metodologías Lúdicas como recurso didáctico y psicopedagógico en Educación In...Campuseducación
Curso de formación para Oposiciones de MAESTROS de EDUCACIÓN INFANTIL y MAESTROS DE EDUCACIÓN PRIMARIA homologado por la Universidad Camilo José Cela, de 110 horas, 4 créditos ECTS y 11 semanas de duración.
Welding process /certified fixed orthodontic courses by Indian dental acad...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
00919248678078
Welding is a fabrication process used to join materials, typically metals or thermoplastics, by causing fusion, leading to the creation of a strong, permanent bond. Various welding processes exist, each with its own techniques, applications, and suitability for different materials and conditions. Some of the common welding processes include:
Shielded Metal Arc Welding (SMAW):
Commonly known as "stick welding," it uses a consumable electrode coated with flux to create the weld.
It's versatile and widely used in construction, maintenance, and repair work.
Gas Metal Arc Welding (GMAW/MIG - Metal Inert Gas):
Uses a continuous solid wire electrode and a shielding gas (typically argon or a mix of gases) to protect the weld area from atmospheric contamination.
Generally used in manufacturing, automotive, and construction industries.
Gas Tungsten Arc Welding (GTAW/TIG - Tungsten Inert Gas):
Uses a non-consumable tungsten electrode and a separate filler material if needed.
Often used for thin materials, critical welds, or where precise control is necessary.
Flux-Cored Arc Welding (FCAW):
Similar to MIG welding but uses a tubular wire filled with flux instead of a solid wire and external shielding gas.
Commonly used in heavy equipment manufacturing and construction.
Submerged Arc Welding (SAW):
Involves feeding a continuous, solid filler wire electrode and granular flux over the weld zone.
Ideal for heavy industrial applications due to its high deposition rates.
Resistance Spot Welding (RSW):
Joins metals by applying pressure and passing current through the metals using copper alloy electrodes.
Widely used in automotive manufacturing and sheet metal applications.
Oxy-Fuel Welding (OFW):
Uses fuel gases and oxygen to weld and cut metals.
Still used for maintenance and repair work, though its use has declined in favor of other processes.
Electron Beam Welding (EBW) and Laser Beam Welding (LBW):
Utilize highly focused beams of electrons or lasers to create high-quality welds in precise and delicate applications, often in aerospace or electronics industries.
Each welding method has its advantages and limitations, making certain techniques better suited for specific applications based on factors like material type, thickness, required strength, and the environment in which the welding will be performed.
Welding processes continue to evolve, with advancements in technology improving efficiency, precision, and safety, and newer techniques being developed to cater to specific industrial needs and challenges.
In this topic you will get ideas about second law of thermodynamic,heat engine and Internal Combustion engine.Its very beneficial for Mechanical Engineering students as well as Automobile Engineering students.
In this topic (Thermodynamics)the students will be able to analyze and evaluate Zeroth law and First law of thermodynamic cycles used for energy production - work and heat, within the natural limits of conversion.
In this presentation you will get knowledge about shear force and bending moment diagram and this topic very useful for civil as well as mechanical engineering department students.
To become science-based engineers, having a thorough knowledge of basic science or physical science, a broad knowledge of the principles and methods of mechanics, and an ability to apply those fundamentals in practical situations.Its very important for all students of engineering/diploma holders of any branch.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Forklift Classes Overview by Intella PartsIntella Parts
Discover the different forklift classes and their specific applications. Learn how to choose the right forklift for your needs to ensure safety, efficiency, and compliance in your operations.
For more technical information, visit our website https://intellaparts.com
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
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.
Automobile Management System Project Report.pdfKamal Acharya
The proposed project is developed to manage the automobile in the automobile dealer company. The main module in this project is login, automobile management, customer management, sales, complaints and reports. The first module is the login. The automobile showroom owner should login to the project for usage. The username and password are verified and if it is correct, next form opens. If the username and password are not correct, it shows the error message.
When a customer search for a automobile, if the automobile is available, they will be taken to a page that shows the details of the automobile including automobile name, automobile ID, quantity, price etc. “Automobile Management System” is useful for maintaining automobiles, customers effectively and hence helps for establishing good relation between customer and automobile organization. It contains various customized modules for effectively maintaining automobiles and stock information accurately and safely.
When the automobile is sold to the customer, stock will be reduced automatically. When a new purchase is made, stock will be increased automatically. While selecting automobiles for sale, the proposed software will automatically check for total number of available stock of that particular item, if the total stock of that particular item is less than 5, software will notify the user to purchase the particular item.
Also when the user tries to sale items which are not in stock, the system will prompt the user that the stock is not enough. Customers of this system can search for a automobile; can purchase a automobile easily by selecting fast. On the other hand the stock of automobiles can be maintained perfectly by the automobile shop manager overcoming the drawbacks of existing system.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
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.
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.
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/
3. WELDING
– Welding is a materials joining process which produces coalescence
of materials by heating them to suitable temperatures with or
without the application of pressure or by the application of pressure
alone, and with or without the use of filler material.
– Welding is used for making permanent joints.
– It is used in the manufacture of automobile bodies, aircraft frames,
railway wagons, machine frames, structural works, tanks, furniture,
boilers, general repair work and ship building.
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4. TYPES
• Plastic Welding or Pressure Welding
The piece of metal to be joined are heated to a
plastic state and forced together by external pressure
(Ex) Resistance welding
• Fusion Welding or Non-Pressure Welding
The material at the joint is heated to a molten state and
allowed to solidify
(Ex) Gas welding, Arc welding
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5. Classification of welding processes:
(i). Arc welding
• Carbon arc
• Metal arc
• Metal inert gas
• Tungsten inert gas
• Plasma arc
• Submerged arc
• Electro-slag
(ii). Gas Welding
• Oxy-acetylene
• Air-acetylene
• Oxy-hydrogen
(iii). Resistance Welding
• Butt
• Spot
• Seam
• Projection
• Percussion
(iv)Thermit Welding
(v)Solid State Welding
Friction
Ultrasonic
Diffusion
Explosive
(vi)Newer Welding
Electron-beam
Laser
(vii)Related Process
Oxy-acetylene cutting
Arc cutting
Hard facing
Brazing
Soldering
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6. Arc welding
• Equipments:
• A welding generator (D.C.) or Transformer (A.C.)
• Two cables- one for work and one for electrode
• Electrode holder
• Electrode
• Protective shield
• Gloves
• Wire brush
• Chipping hammer
• Goggles
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7. Power Source in Arc Welding
• Direct current (DC) vs. Alternating current (AC)
– AC machines less expensive to purchase and operate, but
generally restricted to ferrous metals
– DC equipment can be used on all metals and is generally
noted for better arc control
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9. Arc Welding
Uses an electric arc to coalesce
metals
Arc welding is the most common
method of welding metals
Electricity travels from electrode to
base metal to ground
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10. Fusion Welding: Arc Welding (AW)
A fusion welding process in which coalescence of the metals is achieved by the
heat from an electric arc between an electrode and the work
1. Electric energy from the arc produces temperatures ~ 10,000 F (5500 C),
hot enough to melt any metal.
2. Most AW processes add filler metal to increase volume and strength of weld
joint.
3. A pool of molten metal is formed near electrode tip, and as electrode is
moved along joint, molten weld pool solidifies in its wake
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11. Arc and Power Source Characteristics in
Arc Welding
Arc Characteristics
Power Source Characteristics
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12. Two Basic Types of Arc Welding
(Based on Electrodes)
1. Consumable electrodes
consumed during welding process
added to weld joint as filler metal
in the form of rods or spools of wire
2. Non-consumable electrodes
not consumed during welding process but does get gradually
eroded
filler metal must be added separately if it is added
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13. Arc welding (AW): Arc Shielding
1. At high temperatures in AW, metals are chemically reactive to
oxygen, nitrogen, and hydrogen in air
Mechanical properties of joint can be degraded by these
reactions
Arc must be shielded from surrounding air in AW processes
to prevent reaction
2. Arc shielding is accomplished by
Shielding gases, e.g., argon, helium, CO2
Flux
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14. Arc welding (AW): Flux
A substance that prevents formation of oxides and other
contaminants in welding, which comes from
1. granules that are created from the welded material.
2. a coating on the stick electrode that melts during welding to
cover operation.
3. a core that is within tubular electrodes and is released as
electrode is consumed.
Melts during welding to be liquid slag that hardens when
cooled. The slag should be removed for a clean look by
brushing or grinding off.
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15. Consumable Electrode AW Processes
Shielded Metal Arc Welding (or Stick Welding)
Gas Metal Arc Welding (or Metal Inert Gas Welding)
Flux-Cored Arc Welding
Electro-gas Welding
Submerged Arc Welding
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16. Uses a consumable electrode consisting of a filler metal rod and coating
around rod.
Coating composed of chemicals that provide flux and shielding.
Low cost welding system: Power supply, connecting cables, and electrode
holder available for $300 to $400.
AW: Consumable: Shielded Metal Arc Welding
(SMAW)
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17. SMAW Applications
Used for steels, stainless steels, cast irons, and certain
nonferrous alloys.
Not used or rarely used aluminum and its alloys, copper
alloys, and titanium.
Can be used in windy weather.
Can be used on dirty metals (i.e. painted or rusted surfaces).
Good for repair work.
Makes thick welds.
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18. AR: Consumable: Gas Metal Arc Welding
(GMAW) or Metal Inert Gas (MIG) Welding
Uses a consumable bare metal wire as electrode with shielding by
flooding arc with a gas
1. Wire is fed continuously and automatically from a spool
through the welding gun.
2. Shielding gases include argon and helium for aluminum
welding, and CO2 for steel welding.
3. Bare electrode wire (no flux) plus shielding gases eliminate
slag on weld bead. No need for manual grinding and cleaning
of slag
4. Medium cost welding system: $1000 to $1200
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19. Gas Metal Arc Welding
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20. GMAW Advantages over SMAW
1. Continuous welding because of continuous wire electrode.
Sticks must be periodically changed in SMAW.
2. Higher deposition rates.
3. Eliminates problem of slag removal.
4. Can be readily automated.
5. Has better control to make cleaner & narrower welds than
SMAW.
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21. GMAW Applications
1. Used to weld ferrous and various non-ferrous and metals.
2. Good for fabrications such as frames and farm equipment.
3. Can weld thicker metal (not as thick as SMAW).
4. Metal must be clean to start weld.
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23. AW: non-consumable: Gas Tungsten Arc Welding
(GTAW) or Tungsten Inert Gas (TIG) Welding
Uses a non-consumable tungsten electrode and an inert gas for arc
shielding
1. Melting point of tungsten = 3410C (6170F).
2. Used with or without a filler metal. When filler metal used, it is
added to weld pool from separate rod or wire.
3. Applications: aluminum and stainless steel mostly.
4. High cost for welding system: $4000.
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24. Gas Tungsten Arc Welding
Filler rod
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25. Advantages and Disadvantages of GTAW
Advantages:
1. High quality welds for suitable applications
- Welds are cleaner and narrower than MIG
2. No spatter because no filler metal through arc
3. Little or no post-weld cleaning because no flux
Disadvantages:
1. More difficult to use than MIG welding
2. More costly than MIG welding
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26. GTAW Applications
1. Used to weld ferrous and various non-ferrous and metals.
2. Can weld various dissimilar metals together.
3. Good for fabrications such as aircraft or race car frames.
4. Used for welding thinner metal parts (not as thick as MIG).
5. Metal must be very clean to start weld.
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28. Advantages and Disadvantages of PAW
Advantages:
• Good arc stability and excellent weld quality
• Better penetration control than other AW processes
• High travel speeds
• Can be used to weld almost any metals
Disadvantages:
• High equipment cost
• Larger torch size than other AW processes
– Tends to restrict access in some joints
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30. Friction Welding (Inertia Welding)
• One part rotated, one stationary
• Stationary part forced against
rotating part
• Friction converts kinetic energy to
thermal energy
• Metal at interface melts and is
joined
• When sufficiently hot, rotation
is stopped & axial force
increased
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Inertia Welding
31. Friction Welding (FRW)
SSW process in which coalescence is achieved by frictional heat
combined with pressure
• When properly carried out, no melting occurs at faying
surfaces
• No filler metal, flux, or shielding gases normally used
• Process yields a narrow HAZ
• Can be used to join dissimilar metals
• Widely used commercial process, amenable to automation and
mass production
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32. • (1) Rotating part, no contact; (2) parts brought into contact to
generate friction heat; (3) rotation stopped and axial pressure
applied; and (4) weld created
Friction Welding
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33. Applications and Limitations of Friction Welding
Applications:
• Shafts and tubular parts
• Industries: automotive, aircraft, farm equipment, petroleum
and natural gas
Limitations:
• At least one of the parts must be rotational
• Flash must usually be removed (extra operation)
• Upsetting reduces the part lengths (which must be taken into
consideration in product design)
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34. • Good for dissimilar metals
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Diffusion Welding
• Parts forced together at high temperature
(< 0.5Tm absolute) and pressure
• Atoms diffuse across interface
• Heated in furnace or by resistance heating
• Bond can be weakened by surface
impurities
•After sufficient time the interface disappears
35. Resistance Welding (RW)
A group of fusion welding processes that use a combination of
heat and pressure to accomplish coalescence
• Heat generated by electrical resistance to current flow at
junction to be welded
• Principal RW process is resistance spot welding (RSW)
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36. Resistance Welding
• Resistance welding,
showing components in
spot welding, the main
process in the RW
group
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37. Components in Resistance Spot Welding
• Parts to be welded (usually sheet metal)
• Two opposing electrodes
• Means of applying pressure to squeeze parts between
electrodes
• Power supply from which a controlled current can be applied
for a specified time duration
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38. Resistance Spot Welding (RSW)
Resistance welding process in which fusion of faying surfaces of
a lap joint is achieved at one location by opposing electrodes
• Used to join sheet metal parts
• Widely used in mass production of automobiles, metal
furniture, appliances, and other sheet metal products
– Typical car body has ~ 10,000 spot welds
– Annual production of automobiles in the world is
measured in tens of millions of units
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39. • (a) Spot welding cycle
• (b) Plot of force and
current
• Cycle: (1) parts
inserted between
electrodes, (2)
electrodes close, (3)
current on, (4) current
off, (5) electrodes
opened
Spot Welding Cycle
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40. Advantages and Drawbacks of Resistance Welding
Advantages:
• No filler metal required
• High production rates possible
• Lends itself to mechanization and automation
• Lower operator skill level than for arc welding
• Good repeatability and reliability
Disadvantages:
• High initial equipment cost
• Limited to lap joints for most RW processes
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41. Resistance Seam Welding (RSEW)
Uses rotating wheel electrodes to produce a series of
overlapping spot welds along lap joint Can produce
air-tight joints.
Applications:
– Gasoline tanks
– Automobile mufflers
– Various sheet metal containers
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43. Resistance Projection Welding (RPW)
A resistance welding process in which coalescence occurs at one
or more small contact points on the parts
• Contact points determined by design of parts to be joined
• May consist of projections, embossments, or localized
intersections of parts
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44. (1) Start of operation, contact between parts is at projections;
(2) when current is applied, weld nuggets similar to spot welding
are formed at the projections
Resistance Projection Welding
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44
45. Other Resistance Projection Welding Operations
• (a) Welding of fastener on sheet metal and (b) cross-wire
welding
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46. Arc welding
Advantages
– Most efficient way to join
metals
– Lowest-cost joining
method
– Affords lighter weight
through better utilization
of materials
– Joins all commercial
metals
– Provides design flexibility
Limitations
• Manually applied, therefore
high labor cost.
• Need high energy causing
danger
• Not convenient for
disassembly.
• Defects are hard to detect at
joints.
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47. Comparison of A.C. and D.C. arc welding
Alternating Current (from Transformer)
More efficiency
Power consumption less
Cost of equipment is less
Higher voltage – hence not safe
Not suitable for welding non ferrous metals
Not preferred for welding thin sections
Any terminal can be connected to the work or electrode
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48. Direct Current (from Generator)
Less efficiency
Power consumption more
Cost of equipment is more
Low voltage – safer operation
suitable for both ferrous non ferrous metals
preferred for welding thin sections
Positive terminal connected to the work
Negative terminal connected to the electrode
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49. SMAW - DC Polarity
Straight Polarity Reverse Polarity
Shallow penetration
(thin metal)
(+)
(–)
Deeper weld penetration
(–)
(+)
AC - Gives pulsing arc
- used for welding thick sections
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Electric arc welding --Polarity
50. OXYFUEL WELDING
• OFW is the term to describe the group of fusion operations that
burn various fuels mixed with oxygen to perform welding.
• The OFW processes employ several type of gases, which is the
primary distinction among the members of this group.
• The most important OFW process is oxyacetylene welding. Filler
materials are used to supply additional material to the weld zone.
Flux is often used to clean the surfaces and to retard oxidation by
providing inert gas shield around the weld area. It also helps in
removing oxide and other impurities. Borax, is the most common
flux, but sometimes other substances are added to improve its
effectiveness.
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51. OXYFUEL WELDING
• The heat is obtained by combustion of acetylene and oxygen.
Here primary combustion occurring in the inner zone gives:
C2 H2 + O2 → 2CO + H2 + Heat
and the second reaction in the outer zone gives:
2CO + H2 + 1.5O2 → 2CO2 + H2 O + Heat
• The maximum temperature at the tip of inner cone reaches up
to 3000-3500°C. Therefore, most gas welding is performed by
keeping this inner zone tip just above the metal to be welded
so that maximum temperature is available for welding.
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52. GAS WELDING EQUIPMENT...
1. Gas Cylinders
Pressure
Oxygen – 125 kg/cm2
Acetylene – 16 kg/cm2
2. Regulators
Working pressure of oxygen 1 kg/cm2
Working pressure of acetylene 0.15 kg/cm2
Working pressure varies depends upon the thickness of the work
pieces welded.
3. Pressure Gauges
4. Hoses
5. Welding torch
6. Check valve
7. Non return valve
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55. TYPES OF FLAMES…
• Oxygen is turned on, flame immediately changes into a long white
inner area (Feather) surrounded by a transparent blue envelope is
called Carburizing flame (30000c)
• Addition of little more oxygen give a bright whitish cone
surrounded by the transparent blue envelope is called Neutral flame
(It has a balance of fuel gas and oxygen) (32000c)
• Used for welding steels, aluminum, copper and cast iron
• If more oxygen is added, the cone becomes darker and more
pointed, while the envelope becomes shorter and more fierce is
called Oxidizing flame
• Has the highest temperature about 34000c
• Used for welding brass and brazing operation
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57. Three basic types of oxyacetylene flames used in oxyfuel-gas
welding and cutting operations: (a) neutral flame; (b) oxidizing
flame; (c) carburizing, or reducing flame.
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58. Three basic types of oxyacetylene flames used in oxyfuel-gas
welding and cutting operations:
(a) neutral flame; (b) oxidizing flame; (c) carburizing, or reducing
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60. TYPES OF FLAMES…
• A neutral flame is obtained when the ratio of is oxygen and acetylene
is 1. Most gas welding operations are carried out by this flame.
• An oxidizing flame is obtained when this ratio is more than 1. This
type of flame is not suitable for welding of steels since excess oxygen
present reacts with carbon in steel and is generally used for welding of
copper and its alloys.
• When the ratio in mixture is less than 1 a carburizing flame is
obtained. In this type of flame acetylene decomposes into carbon and
hydrogen and the flame temperature gets reduced. Joining operations
such as brazing and soldering which require lower temperature
generally use this flame
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61. Weld defects
Classification of Weld Joint Discontinuities
Geometric
• Misalignment
• Undercut
• Concavity or Convexity
• Excessive Reinforcement
• Improper Reinforcement
• Overlap
• Burn-through
• Backing left on
• Incomplete Penetration
• Lack of Fusion
• Shrinkage
• Surface Irregularities
Other
• Arc Strikes
• Slag Inclusions
• Tungsten Inclusions
• Oxide Films
• Spatter
• Arc Craters
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63. POROSITY
• Porosity is the entrapment of
small volumes of gas in
solidifying weld metal
• Prevention
– Drying consumables
– Cleaning, degreasing
material being welded
– Electrode or filler metals
with higher level of
deoxidants
– Sealing air leaks, reducing
excess shielding gas flow
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64. Molten weld metal is able to hold more gas than solid weld
metal. For this reason, gas bubbles tend to evolve as the liquid
metal solidifies. These gas bubbles trapped within the solid weld
metal are referred to as porosity. Although porosity is sometimes
noted at the surface of a weld, visual inspection cannot detect
internal porosity. Radiography and ultrasonic methods are
required. Localized regions of porosity can be cut from a weld; a
repair is then made. For general porosity throughout a weld, the
entire weld must be gouged out and rewelded.
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65. SLAG INCLUSIONS
• Slag inclusions, as the name
implies, are small pieces of welding
slag which are trapped in the weld
metal. Unlike porosity, which is
usually spherical, slag inclusions are
irregularly shaped. Since these are
internal discontinuities, radiography
or ultrasonic testing is required for
detection. Weld regions containing
slag inclusions must be cut out and
rewelded.
Slag inclusions are irregularly shaped,
not spherical like porosity Prevention
Position work and/or change
electrode/flux to increase slag
control
Better slag removal between passes
Dress weld surface smooth if it is
likely to cause slag traps
Remove heavy mill scale on plate
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66. LACK OF FUSION
• Lack of fusion is caused by
incorrect welding conditions
• Prevention
– Procedure for complete
fusion should be verified
by testing
– Increased energy input
– Correct electrode angle
and work position
• Lack of fusion can occur at
the weld sidewall, root, or
between individual passes.
Magnetic particle and dye or
fluorescent penetrant may
be used to detect this
discontinuity if it reaches
the surface. Otherwise,
radiography or ultrasonic
methods must be used.
Affected regions must be
cut out and rewelded.
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67. INCOMPLETE ROOT PENETRATION
• Incomplete root penetration can
be caused by
– Excessively thick root face,
insufficient root gap
– Incorrect welding conditions
– Misalignment of second weld
• Prevention
– Improved joint preparation
– Test weld verifications for
correct parameters
– Reassessment of back
gouging
• Incomplete root penetration is the
failure of a weld to extend into the
root of a joint. For a double weld,
it is an internal discontinuity and
can be detected only by
radiography or ultrasonic testing.
It can be detected by magnetic
particle, and dye or fluorescent
penetrant methods if the root side
is accessible. A long pipeline
would be an example of when the
weld root (inside the pipe) would
not be accessible. This defect is
repaired by cutting it out and
rewelding.
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68. OVERLAP
• Overlap is an imperfection at
the weld toe or root caused by
metal flowing onto the surface
of the base metal without
fusing to it
• Prevention
– Adjust electrode
manipulation to ensure
fusion of base metal
– Limit size of fillet to 9-
mm leg length
• Overlap is often associated with
horizontal welding; welding in
the flat position can help to
eliminate this problem. Overlap
can be detected visually and can
be supplemented with dye
penetrant. It is corrected by
cutting back to sound weld
metal. Rewelding may be
necessary
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69. UNDERCUT
• Undercut is an irregular
groove at the weld toe in the
parent metal or previous
pass caused by
– excessive weaving
– melting of top edge of fillet
weld with high current
• Prevention
– Weld in flat position
– Change shielding gas to
one which produces better
wetting
– Terminate welds so they
don’t finish at a free edge
• Undercut is another defect that can
be associated with horizontal
welding among other factors such
as high current and excessive
weaving. Flat position welding
can aid in eliminating this
discontinuity. It is detected
visually and measured by a depth
gauge. Deep undercut is ground
out and weld repaired
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70. SPATTER
• Spatter consists of small droplets of
electrode material that land beside the
weld and may or may not fuse to the
base material
• Prevention
– Reduce energy input
– Shorter arc length
– Reposition current return clamp to
reduce magnetic arc blow or switch to
AC current
• As metal drops transfer from the
electrode to the weld pool, some are
blown clear of the weld and form drops
of spatter on the base plate. All open
arc consumable electrode processes
produce some spatter.
• Spatter can occur when the energy input
is too high or when the arc length is
excessive. Arc blow can also cause
spatter, as can insufficient inductance in
GMAW or CO2 welding.
• Spatter can be detected visually. It can
be removed by scraping or by light
grinding. Anti-spatter coatings are
available on the market that prevent
spatter from adhering to the base
material.
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71. GAS CUTTING
• Ferrous metal is heated in to red hot condition and a jet of pure
oxygen is projected onto the surface, which rapidly oxidizes
• Oxides having lower melting point than the metal, melt and are
blown away by the force of the jet, to make a cut
• Fast and efficient method of cutting steel to a high degree of
accuracy
• Torch is different from welding
• Cutting torch has preheat orifice and one central orifice for oxygen
jet
• PIERCING and GOUGING are two important operations
• Piercing, used to cut a hole at the centre of the plate or away from
the edge of the plate
• Gouging, to cut a groove into the steel surface
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72. Flame Cutting
• Metal is merely melted by the
flame of the oxyfuel gas torch
and blown away to form a gap or
kerf.
• When ferrous metal is cut,
actually burning of iron takes
place according to one or more
of the following reactions
Fe+ O Feo+ Q
3Fe+2 O2 Fe3 O4+ Q
4Fe+3 O2 2Fe2 O3 + Q
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73. • Because, these reactions cannot take place below 815°C oxyfuel flame is first used to raise
the metal temperature where burning can be initiated. Then a stream of pure oxygen is
added to the torch (or the oxygen content of the oxyfuel mixture is increased) to oxidize
the iron. The liquid iron and iron oxides are then expelled from the joint by the kinetic
energy of the oxygen gas stream.
• Low rate of heat input, and need of preheating ahead of the cut, oxyfuel produces a
relatively large heat affected zone and thus associated distortion zone.
• The process is suitable when edge finish or tolerance is not critical.
• Theoretically heat generated due to burning of Fe is sufficient to continue cutting however
due to losses additional heat supply is needed. If the work is already hot due from the
other processes, supply of oxygen through a small diameter pipe is needed to continue cut.
This is called Oxygen Lance Cutting. A work piece temperature of 1200°C is needed to
sustain the cutting.
• Low carbon steel from 5 to 75 mm can be cut.
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76. SOLID / LIQUID STATE BONDING
• Low temperature joining methods are used when the metal to
be joined cannot withstand high temperature, or intricate
sections are to be joined, or dissimilar metals are to be joined,
or weldability of material is poor.
• In these methods, the gap between the metal pieces to be
joined is filled with molten filler material after heating the
base metal. Melting point of filler material is much lower than
base metals.
• The bonding is not due to melting of parent metal and fusion.
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77. • Filler material is drawn into the gap between the metal pieces
to be joined by capillary action and the bond formation is
initiated when the molten filer metal comes under intimate
contact with the solid surface as in solid state welding.
• The nature of bond formed is much complex here, and
invariably there is some degree of intersolubility between filler
and base metals.
• This inter-diffusion at the base metal surface and resulting
alloy has a strength which is very close to that the base metal.
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78. • For a good joint strength the liquid filler
metal; must flow into the gap between
the metal pieces to be joined and cover
the entire surface area, without gaps or
blow holes. The following usually
insures good bonding:
– Clean base metal surfaces
– Maintain optimum gap
– Heat the joining area above melting
temperature of the filler material
– Use fluxes for welding of base metal
surfaces.
• Joint strength is sensitive to the gap and
there exists an optimum gap for a filler
material.
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79. Brazing and Soldering
• Brazing
It is a low temperature joining process. It is performed at
temperatures above 840º F and it generally affords strengths
comparable to those of the metal which it joins. It is low
temperature in that it is done below the melting point of the base
metal. It is achieved by diffusion without fusion (melting) of the
base
Brazing can be classified as
Torch brazing
Dip brazing
Furnace brazing
Induction brazing
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80. BRAZING
Brazing methods
(a) Torch and filler rods
(b) Ring of filler metal at
entrance of Gap
(c) Foil of filler metal
between flat part surfaces
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81. • In brazing the joint is made by heating the base
metal red hot and filling the gap with molten
metal whose melting temperature is typically
above 450°C but below melting temperature o
base metal. The filler metals are generally
copper alloys. Cu-Zn and Cu-Ag alloys are
used for brazing because they form alloy with
iron and have good strength.
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82. VARIOUS BRAZING JOINTS
(a) Conventional butt
(b) Scarf joint
(c) Stepped joint
(d) Increased crossest ion
(a)Conventional Lap
(b) Cylindrical part
(c) Sandwiched part
(d) Use of sleeve
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84. Advantages & Disadvantages
Advantages
• Dissimilar metals which can not be welded can be joined by brazing
• Very thin metals can be joined
• Metals with different thickness can be joined easily
• In brazing thermal stresses are not produced in the work piece.
Hence there is no distortion
• Using this process, carbides tips are brazed on the steel tool holders
Disadvantages
• Brazed joints have lesser strength compared to welding
• Joint preparation cost is more
• Can be used for thin sheet metal sections
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85. SOLDERING
• Soldering is very similar to brazing except that filler material
is usually a lead-tin based alloy which has much lower
strength and melting temperature around 250°C.
• In this process less alloying action between base metal and
filler material as compared to brazing takes place hence the
strength of joint is lesser.
• It is carried out using electrical resistance heating
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86. Soldering
• It is a low temperature joining
process. It is performed at
temperatures below 840ºF for
joining.
• Soldering is used for,
• Sealing, as in automotive
radiators or tin cans
• Electrical Connections
• Joining thermally
sensitive components
• Joining dissimilar metals
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87. THERMIT WELDING (TW)
FW process in which heat for coalescence is produced by
superheated molten metal from the chemical reaction of
thermite
• Thermite = mixture of Al and Fe3O4 fine powders that produce
an exothermic reaction when ignited
• Also used for incendiary bombs
• Filler metal obtained from liquid metal
• Process used for joining, but has more in common with casting
than welding
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88. • (1) Thermit ignited; (2) crucible tapped, superheated metal
flows into mold; (3) metal solidifies to produce weld joint
Thermit Welding
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89. TW Applications
• Joining of railroad rails
• Repair of cracks in large steel castings and forgings
• Weld surface is often smooth enough that no finishing is
required
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90. WELDING METALLURGY
• In fusion welded joint, where three distinct zones can be
identified:-
• The base metal
• The heat affected Zone
• The fusion Zone
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91. Two major concerns occur in the heat affected zone which
effect weldability these are, a.) changes in structure as a result
of the thermal cycle experienced by the passage of the weld
and the resulting changes in mechanical properties coincident
with these structural changes, and b.) the occurrence of cold or
delayed cracking due to the absorption of hydrogen during
welding.
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92. Heat Affected Zone
• The Heat-Affected Zone (HAZ) is an area of a base metal which, while
not melted, still has had its chemical properties altered by high temperature
heat. This phenomenon primarily occurs during welding or high-heat
cutting. The high temperature from the welding process and eventual re-
cooling causes this change from the weld interface to the end of the
sensitizing temperature in the metal. These areas can be varying sizes and
levels of severity.
• The metallurgical changes that can occur at the HAZ tend to cause stresses
that reduce the strength of the material. The HAZ can also suffer from a
decreased resistance to corrosion and/or cracking (i.e, sensitization). These
metallurgical changes can also lead to the formation of nitrides at the HAZ,
which can affect weldability. In addition, the microstructure at the HAZ can
be altered in a way that increases its hardness compared to the surrounding
material. Hardness, sensitization, and high local stresses in or near the HAZ
may be mitigated by practices such as controlled pre- and post-weld heat
treatment and solution annealing.
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93. How much these changes in metallurgical and physical
properties can affect the HAZ of the material is dependent
on a number of factors, including the base material, the
weld filter metal, and the amount and concentration of heat
input during the welding process.
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95. Hardfacing
Hard facing is a metalworking process where harder or tougher
material is applied to a base metal. It is welded to the base
material, and generally takes the form of specialized electrodes
for arc welding or filler rod for oxyacetylene and TIG welding.
Powder metal alloys are used in (PTA) also called Powder plasma
welding system and Thermal spray processes like HVOF, Plasma
spray, Spray and Fuse, etc.
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96. • Hard facing may be applied to a new part during production to
increase its wear resistance ,or it may be used to restore a worn-
down surface. Hard facing by arc welding is a surfacing operation
to extend the service life of industrial components, pre-emptively
on new components, or as part of a maintenance program. The
result of significant savings in machine down time and production
costs has meant that this process has been adopted across many
industries such as Steel, Cement, Mining, Petro chemical, Power,
Sugar cane and Food. According to the results of an experimental
study, the SMAW (Shielded Metal Arc Welding) and the GMAW
(Gas Metal Arc Welding)hard facing processes were effective in
reducing the wear on the mould board ploughshare. With the
SMAW and GMAW hard facing processes, the life span of the
ploughshare was increased approximately 2 times.
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97. Cladding
Cladding is the bonding together of dissimilar metals. It is
different from fusion welding or gluing as a method to fasten the
metals together. Cladding is often achieved by extruding two
metals through a die as well as pressing or rolling sheets together
under high pressure.
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98. Microstructure Welding
The microstructural studies of friction welding helps in
understanding microstructural changes occurred during
friction welding process. High temperature and strain during
friction welding process changes the microstructure of the
parent material.
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99. Welding Symbols
Representation of welds on drawings requires the use of following
elements-
1. A basic symbol to specify each type of weld.
2. A reference line and an arrow to indicate the location the weld in a
joint.
3. Supplementary symbols to mark weld-all-round, finish of welds
etc.
4. Weld dimensions in cross-section and in length.
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101. WELDING DESIGN
Before an arc can be struck on metal, the product must be designed to serve its
purpose, the material chosen and the method of welding determined in more or
less detail.
The weldment design engineer must
I. Know the limitations and specific requirements of the processes as well
as the equipment available on the shop floor.
II. Have a good working knowledge of the shop problems of shrinkage and
distortion.
III. Have accurate knowledge not only of suitability but also of availability of
materials or the costs of extras.
IV. Be able to calculate stresses, strengths and determine weld sizes and put
these together to work out a design that meets all service requirements.
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102. Welding Joint Design
since, welding joins metals, design for welding is chiefly concerned with
joints-when to use a joint, how to weld it, where to place it, what to do and
what not to do.
Selection and preparation of weld joints is an important step in the fabrication
of a weldment.
Selection of correct joint design is very essential if welded members are to
perform within the load service, corrosive atmosphere and safety requirements.
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103. Welding
Fusion Welding (FW)
Solid State Welding (SSW)
Consumable electrodes Non-consumable electrodes
Summary
Shielding
Flux
Various welding processes (AW) are developed to address the two issues: shielding and
flux
Arc weldingOxyfuel welding
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