Welding Classification

7/31/2019 Welding Classification

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WELDING

BY

T.MOHAN REDDY,SM(FQA)


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WELDING PROCESS

WELDING PROCESS

SOLID PHASE FUSION WELDING

JOINING BELOW MELTING POINTJOINING AT BEYOND MELTINGPOINT


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SOLID PHASE WELDING

FRICTION WELDING

FLASH BUTT WELDING

EXPLOSIVE WELDING DIFFSION WELDING


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FRICTION WELDING

What Is Friction Welding?

Friction Welding is a completelymechanical solid phase process in whichheat is generated by friction to produce ahigh integrity welded joint between similaror dissimilar metals.


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ADVANTAGES

The advantages are both metallurgical and physical. A bonded jointis formed using no filler metal, flux or shield gas. The process isenvironmentally clean; no arcs, sparks, smoke or flames aregenerated by clean parts. Surface preparation/cleanliness is notsignificant with most materials since the process burns through anddisplaces surface impurities. During the friction welding process

there are narrow heat affected zones. The process is suitable forwelding most engineering materials and is well suited for joiningmany dissimilar combinations. In most cases, the weld strength is asstrong or stronger than the weaker of the two materials being joined.Operators are not required to have manual welding skills. Frictionwelding requires only simple integration into the manufacturing area.The process is easily automated for mass production. Welds aremade rapidly compared to other welding processes. Plantrequirements (space, power, special foundation etc.) are minimal forthe friction welding process.


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TYPICAL APPLICATIONS

ENGINE VALVES

TRANSMISSION DRIVE SHAFTS

DRILL RODS

HYDRAULIC CYLINDERS

FILTER CATRIDGES

DRILL BITS

ELECTRICAL CONNECTORS

VIHICLE AIR BAGS


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FLASHBUTT WELDING

Flash Butt Welding, also known as Flash Welding,uses an arc between the two mating parts as theybegin to make contact. It is commonly used to joinsimilar or dissimilar metals for end-to-end or edge-

to-edge welds. The electrical resistance at the joint raises the

temperature and plastic deformation forms the finalweld. Impurities and contaminants are squeezed outduring this operation resulting in an excellent weld,

but a significant amount of material may be burnt offduring the process. The joint may be machined laterfor improved appearance.


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EXPLOSIVE WELDING

Explosion welding or bonding is a solid statewelding process that is used for the metallurgical

joining of dissimilar metals. The process usesthe forces of controlled detonations to accelerate

one metal plate into another creating an atomicbond. Explosion bonding can introduce thin,diffusion inhibiting interlayers such as tantalumand titanium, which allow conventional weld-upinstallation. Also explosive welding is

considered a cold-welding process which allowsmetals to be joined without losing their pre-bonded properties.


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APPLICATIONS

Dissimilar metal explosion bonded joints are appliedanywhere a designer needs to make a high-qualitytransition between metals. Typical uses includeultra-high vacuum joints between aluminum, copper

and stainless steel, corrosion resistant claddings onmild steel substrates, and alloy aluminum joined tolow-expansion rate metals for electronic packages.Powder metal products such as Glidcop and Al-SiC can be joined to wrought metal without thermal

excursions. Difficult metals such as beryllium, Al-Bealloys and rhenium can be joined with explosionbonding.


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DIFFUSION WELDING

DW, as a special technology, forms a contact on base ofspecial bonding mechanism between metal and substrate. DWis the newest technology compared to standard (sputtering,evaporation, soldering) technologies for manufacturing of highquality contacts, especially on large areas

The DW process has many advantageous, of which veryimportant are: one-step high temperature process formanufacturing multi-layer contacts (low energy process); extrahigh adhesion between layers to be joined; minimum number ofin homogeneities on large area (near defect free contacts); andthe technology improves significantly the certain electricalcharacteristics of manufactured semiconductor devices

compared to other technologies


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For formation of a bonding contact (DWtechnology), three major steps have to be made:

To prepare suitable wafers and metal or ceramic

films into one sandwich; To put the sandwich into a cassette and to

transport it into the vacuum chamber;

To apply a prescribed pressure for a certain time

onto sandwich to promote a penetration ofatoms of each material into neighbour layer(film) for getting extra high quality contacts


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The DW technology is: One step high temperature process, which takes

place in vacuum under mechanical pressure.Temperature does not exceed 500-600 Celsiusdegrees by the pressure about. 50 MPa and themanufacturing time are approximately from 5 to 10minutes;

The lateral homogeneity of the contact area will behigher compared to contacts manufactured byconventional deposited methods, which decreasesthe probability of hot spot creation in the contactduring the device operation.

The DW technology has been shown itself as a veryeffective method by manufacturing the high qualitycontacts to Si, GaAs, SiC, and other materials aswell.


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FUSION WELDING

OXY-ACETELENE GAS WELDING(100WATTS, 3500 C)

ARC WELDING (1000 WATTS, 6000 C)

ELECTRONIC BEAM WELDING(1,00,000 WATTS, 10000 C)

LASER BEAM WELDING (10000 WATTS,10000 C)


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OXYACETYLENE WELDING

Oxyacetylene welding, commonly referred to asgas welding, is a process which relies oncombustion of oxygen and acetylene. When

mixed together in correct proportions within ahand-held torch or blowpipe, a relatively hotflame is produced with a temperature of about3,200 deg.C. The chemical action of the

oxyacetylene flame can be adjusted by changingthe ratio of the volume of oxygen to acetylene.


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PROCESS

Welding is generally carried out using the neutralflame setting which has equal quantities of oxygenand acetylene. The oxidising flame is obtained byincreasing just the oxygen flow rate while the

carburising flame is achieved by increasingacetylene flow in relation to oxygen flow. Becausesteel melts at a temperature above 1,500 deg.C, themixture of oxygen and acetylene is used as it is theonly gas combination with enough heat to weld

steel. However, other gases such as propane,hydrogen and coal gas can be used for joining lowermelting point non-ferrous metals, and for brazingand silver soldering


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EQUIPMENT

Oxyacetylene equipment is portable and easy to use.It comprises oxygen and acetylene gases storedunder pressure in steel cylinders. The cylinders arefitted with regulators and flexible hoses which leadto the blowpipe. Specially designed safety devices

such as flame traps are fitted between the hoses andthe cylinder regulators. The flame trap preventsflames generated by a 'flashback' from reaching thecylinders; principal causes of flashbacks are thefailure to purge the hoses and overheating of the

blowpipe nozzle. When welding, the operator mustwear protective clothing and tinted colouredgoggles. As the flame is less intense than an arc andvery little UV is emitted, general-purpose tintedgoggles provide sufficient protection.


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ELECTRON BEAM WELDING

Electron Beam Welding (EBW) is a fusion joining process thatproduces a weld by impinging a beam of high energy electronsto heat the weld joint. Electrons are elementary atomicparticles characterized by a negative charge and an extremelysmall mass. Raising electrons to a high energy state byaccelerating them to roughly 30 to 70 percent of the speed of

light provides the energy to heat the weld. An EBW gun functions similarly to a TV picture tube. The

major difference is that a TV picture tube continuously scansthe surface of a luminescent screen using a low intensityelectron beam to produce a picture. An EBW gun uses a highintensity electron beam to target a weld joint. The weld joint

converts the electron beam to the heat input required to make afusion weld.


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ELECTRON BEAM WELDING

The electron beam is always generated ina high vacuum. The use of speciallydesigned orifices separating a series of

chambers at various levels of vacuumpermits welding in medium andnonvacuum conditions. Although, high

vacuum welding will provide maximumpurity and high depth to width ratio welds


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ADVANTAGES

Single pass welding of thick joints

Hermetic seals of components retaining avacuum

Low distortion Low contamination in vacuum

Weld zone is narrow

Heat affected zone is narrow

Dissimilar metal welds of some metals

Uses no filler metal


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LIMITATIONS

High equipment cost

Work chamber size constraints

Time delay when welding in vacuum High weld preparation costs

X-rays produced during welding

Rapid solidification rates can causecracking in some materials


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ARC WELDING

ARC WELDING

FLUX SHIELDED(FSAW)

GAS SHIELDED(GSAW)


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GAS SHIELDED ARC WELDING

GSAW

GTAW(GAS TUNGSTON ARC)NON-CONSUMABLE

GMAW(GAS METAL ARC)CONSUMABLE

TIG WELDING PLASMA WELDINGMIG

(METAL INERT GAS)NON-FERROUS

MAG(METAL ACTIVE GAS0

FERROUS

ARGON,HELIUM

CO2,CO2+ARGONO2+ARGON


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GTAW

TIG Welding (GTAW or Gas TungstenArc) - Often called TIG welding (TungstenInert Gas), this welding process joins

metals by heating them with a tungstenelectrode which should not become part ofthe completed weld. Filler metal issometimes used and argon inert gas or

inert gas mixtures are used for shielding.Consumables: tungsten electrode, fillermetal, shielding gas.


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GAS METAL ARC WELDING

MIG (GMAW or Gas Metal Arc Welding) - An arcwelding process which joins metals by heating themwith an arc. The arc is between a continuously fedfiller metal (consumable) electrode and theworkpiece. Externally supplied gas or gas mixtures

provide shielding. Common MIG welding is alsoreferred to as short circuit transfer. Metal isdeposited only when the wire actually touches thework. No metal is transferred across the arc. Anothermethod of MIG welding, spray transfer moves a

stream of tiny molten droplets across the arc fromthe electrode to the weld puddle. Consumables:contact tips, shielding gas, welding wire.


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FLUX SHIELDED ARC WELDING

FLUX SHIELDED ARC

SHIELDED METAL ARC SUBMERGED ARC FLUX CORED ARC


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FLUX CORED ARC WELDING

Flux Cored Arc Welding (FCAW)- An arc weldingprocess which melts and joins metals by heatingthem with an arc between a continuous, consumableelectrode wire and the work. Shielding is obtained

from a flux contained within the electrode core.Depending upon the type of flux-cored wire, addedshielding may or may not be provided fromexternally supplied gas or gas mixture.Consumables: contact tips, flux cored wire,

shielding gas (if required, depends on wire type).


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SAW

Submerged Arc Welding Submerged arc welding (SAW) is a high quality,

very high deposition rate weldingprocess. Submerged arc welding is a high

deposition rate welding process commonly usedto join plate.

Submerged Arc Welding Benefits Extremely high deposition rates possible

High quality welds Easily automated Low operator skill required


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SMAW

Stick Welding Shielded Metal Arc Welding (SMAW) is

frequently referred to as stick or coveredelectrode welding. Stick welding is among the

most widely used welding processes. The fluxcovering the electrode melts duringwelding. This forms the gas and slag to shieldthe arc and molten weld pool. The slag must bechipped off the weld bead after welding. The fluxalso provides a method of adding scavengers,deoxidizers, and alloying elements to the weldmetal.


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SMAW

Stick Welding Benefits

Equipment used is simple, inexpensive,and portable

Electrode provides and regulates its ownflux

Lower sensitivity to wind and drafts thangas shielded welding processes

All position capability


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THANK YOU

Documents

Welding Classification