02abg slides weld proc

8/11/2019 02abg Slides Weld Proc

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WELDING PROCESS ARE BROADLY

CLASSIFIED INTO

1. FUSION WELDING

2. PRESSURE WELDING

TITLE : WELDING INSPECTOR WI : 01


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FUSION WELDING PROCESS1. OXY FUEL WELDING OFW

2. SHIELDED METAL ARC WELDING SMAW3. GAS METAL ARC WELDING GMAW

4. GAS TUNGSTEN ARC WELDING GTAW

5. SUBMERGED ARC WELDING SAW

6. FLUX CORED ARC WELDING FCAW

7. ELECTROSLAG WELDING ESW

8. ELECTROGAS WELDING EGW

9. ELECTRON BEAM WELDING EBW

10. LASER WELDING LW

11. THERMIT WELDING TW



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PRESSURE WELDING PROCESS

1.RESISTANCE WELDING (SPOT, SEAM, PROJECTION)

2.FLASH BUTT WELDING

3.EXPLOSIVE WELDING

4.STUD WELDING

5.FRICTION WELDING

6.INDUCTION WELDING



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APLLICATIONS OF WELDING

BUILDING & BRIDGES AUTOMOBILES, RAILWAYS

SUGAR & CEMENT PLANTS

SHIP BUILDING

POWER GENERATING EQUIPMENT

PETROCHEMICAL & CHEMICAL PLANTS

AIRCRAFT & AEROSPACE INDUSTRIES

ELECTRICAL & ELECTRONIC INDUSTRIES NUCLEAR PLANTS



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SHIELDED METAL ARC WELDING(SMAW)



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ADVANTAGES & DISADVANTAGES OF SMAW

ADVANTAGES DISADVANTAGES1. VERY VERSATILE 1. LOW DEPOSITION RATES

2. SIMPLE EQUIPMENT 2.LOW ARC TIME

3. LOW COST 3.HIGH LEVEL WELDER SKILL

4.EASY ACCESSABILITY

OF ANY JOINT IN ANY

LOCATION

5. EASY AVAILABILITY OFMATCHING ELECTRODES



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TYPES OF ELECTRODES

CELLULOSIC - E6010

RUTILE - E6013

LOW HYDROGEN BASIC COATED - E7018, E7016



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Coating of electrode performs following functions

Provides gas to shield the arc and prevents excessiveatmospheric contamination of the molten metal.

Provides a means of cleaning the base metal just prior to

deposition of the weld metal.

Provides scavengers, deoxidizers, and fluxing agents to clean theweld and prevents excessive grain growth in the weld metal.

Establishes the electrical characteristics of the electrode.

Provides a slag blanket to protect the hot weld metal from the air

and enhance the mechanical properties, bead shape etc. Provides a means of adding alloying elements to change the

mechanical properties of the weld metal.



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AWS CLASSIFICATION OF

ELECTRODE

E X X X X

ELECTRODE

TENSILE STRENGTH WELDING TYPE OF COATING

IN KSI POSITION & CURRENT



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AWS CLASSIFICATION OF ELECTRODE

E 6 0 1 3E - ELECTRODE

60 - 60 KSI TENSSILE STRENGTH

1 - ALL POSITIONS EXCEPT VERTICAL DOWN

3 - RUTILE COATING - AC & DC

REQUIRED MECH. PROPERTIES

TENSILE STRENGTH - 60 KSI (414 N/MM2)

YIELD STRENGTH - 48 KSI (331 N/MM2)ELONGATION - 17 %

IMAPCT - NOT SPECIFIED



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AWS CLASSIFICATION OF ELECTRODE

E 7 0 1 8

E - ELECTRODE

70 - 70 KSI TENSSILE STRENGTH

1 - ALL POSITIONS EXCEPT VERTICAL DOWN

8 - BASIC COATING - AC / DC

REQUIRED MECH. PROPERTIES

TENSILE STRENGTH - 70 KSI (482 N/MM2)

YIELD STRENGTH - 58 KSI (399 N/MM2)

ELONGATION - 22 %

IMAPCT - 27 J @ -290C



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INDIAN STANDARD CLASSIFICATION OF

STICK ELECTRODE IS-8141991

AWS CLASSIFICATION E 6 0 1 3

IS CLASSIFICATION E R 4 2 2 X

EELECTRODE

RRUTILE COVERING

4410 TO 510 N/MM2TENSILE STRENGTH, 330 N/mm2 YIELD

STRENGTH

222% ELONGATION

2ALL POSITION EXCEPT VERTICAL DOWN

2DC WITH NEGATIVE POLARITY RECOMMENDED ACO.C.V 50 V

XRADIOGRAPHIC QUALITY ELECTRODE



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CLASSIFICATION OF ELECTRODES AS PER

INSURANCE AGENCY [D.N.V]

For Normal strength steels : Grade 1, 2, & 3.


GRADE 1 GRADE 2 GRADE 3

Tensile Strength in N/mm2 400560 400560 400560

Yield Strength in N/mm2 305 305 305

% Elongation 22 22 22

Impact properties 47Joules@

200C

47Joules

@ 00C

47Joules@

- 200C


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TYPE OF TESTS REQUIRED TO APPROVEELECTRODES BY INSURANCE AGENCY

[D.N.V]


TYPE OF TEST NO. OF TESTS

Transverse tensile 1

Face bend 1Root bend 1

Charpy Impact test 1 [3 Specimens]

Weld metal chemical 1


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MOISTURE CONTROL OF COATINGS

The presence of moisture in the coatings, either as absorbed

moisture, or present in the coating as combined moisture, is veryimportant in the use of low hydrogen electrodes. This is even more

important in the ship building industry due to the high relative

humidity environments of sea shore. This needs to be controlled by a

proper baking schedule for the low hydrogen electrodes followed by

storage & issue procedures.

It is advantageous to store electrodes in de-humidified rooms.

It is normal for electrodes to be baked at 250-350 deg. C for at least

1-2 hours immediately on being removed from the packets.

It is also important that such baked electrodes are held in holding

ovens at a temperature of > 100 deg. C [typically 150 deg. C] prior

to issue.



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GAS METAL ARC WELDING (GMAW)



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GAS METAL ARC WELDING (GMAW)



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ADVANTGES & LIMITATIONS OF SOLID WIRE

ADVANTAGES LIMITATION

1. LOW-HYDROGEN DEPOSITS. 1. WELDER TRAINING IS

MORE CERITICAL

2. DEPOSITION EFFICIENCIES 2. WELD PARAMETER CONTROL

UP TO 95% CRITICAL FOR WELD QUALITY

3. INDIGENIOUS AVAILABILITY 3.LACK OF FUSION DEFECTS

IS GOOD MORE COMMON ON OUT OF

4.COST OF WIRE IS LOW POSITION WELD

5.PROCEDURE OF 4.LOW DEPOSITION RATES IN

MANUFACTURING SIMPLE OUT OF POSITION WELDING



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MODE OF TRANSFER(GMAW)



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MODE OF TRANSFER(GMAW)



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PROCESS VARIABLES

The following are some of the process variables that affect weld

penetration, bead geometry and overall weld quality.

Welding Current (Electrode feed speed)

Polarity

Arc voltage (Arc length)

Travel speed

Electrode extension

Electrode orientationShielding gas



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WELDING CURRENT(ELECTRODE FEED SPEED)

As the electrode feed speed is varied, the welding amperage willvary in a like manner if a constant voltage power source is used


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POLARITY

The term polarity is used to describe the electrical connection of thewelding gun with relation to terminals of D.C power source. When

the gun is connected to the positive terminal, the polarity is DCEP or

reverse polarity. When the gun is connected to negative terminal, the

polarity is DCEN or straight polarity.

Majority of GMAW applications use direct current electrode positive

(DCEP). This condition yields stable arc, smooth metal transfer,

relatively low spatter, good weld bead characteristics & greaterdepth of penetration for wide range of welding currents.



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POLARITY

The term polarity is used to describe the electrical connection of thewelding gun with relation to terminals of D.C power source. When

the gun is connected to the positive terminal, the polarity is DCEP or

reverse polarity. When the gun is connected to negative terminal, the

polarity is DCEN or straight polarity.

Majority of GMAW applications use direct current electrode positive

(DCEP). This condition yields stable arc, smooth metal transfer,

relatively low spatter, good weld bead characteristics & greaterdepth of penetration for wide range of welding currents.



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ARC VOLTAGE (ARC LENGTH)



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ELECTRODE ORIENTATION

The orientation of the welding electrode with respect to weld joint

affects the weld bead shape and penetration.


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SHIELDING GASES

The primary function of shielding gas is to protect molten weld

metal from atmosphere. the shielding gas & flow rate also have

effect on the following

Arc characteristics

Mode of metal transfer

Penetration & weld bead profile

Speed of welding

Undercutting tendency

Cleaning actionWeld metal mechanical properties

TITLE : WELDING INSPECTOR WI :


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Typical bead profiles for argon, helium,

argon-helium, & CO2



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TYPES OF SHIELDING GASES

1. CARBON DIOXIDE

2. ARGONCO2

3. ARGONO2



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CARBON DIOXIDE



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ARGONCO2 & ARGONO2



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AWS CLASSIFICATION OF SHIELDING GASES

CLASSIFICATION SYSTEM FOR SINGLE GAS

SG - B

Shielding gas designator Base gas designatorCLASSIFICATION SYSTEM FOR MIXTURE OF GASES

SGBX - %

Shielding gas Base gas Component

designator designator



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Carbon dioxide (Co2) : SGC

Argon : SGA

CLASSIFICATION SYSTEM FOR MIXTURE OF GASES

Argon - Co2 Mixture[75+25] : SG-AC-25



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Carbon dioxide (Co2) : SGC

Argon : SGA

CLASSIFICATION SYSTEM FOR MIXTURE OF GASES

Argon - Co2 Mixture[75+25] : SG-AC-25



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USES OF DIFFERENT SHIELDING GASES

FOR GMAW

TITLE : WELDER TRAINING WT : 35

TYPE OF

GASES

TYPICAL

MIXTURE %

PRIMARY USE

Argon - Non ferrous metals

Helium - Al, magnesium & copper alloys

CO2 - Low carbon & low alloy steelsAr + He 20-50A,

50-80He

Al, Magnesium,Copper and

Nickel alloys

Ar + O2 1-2 O2

3-5 O2

Stainless steels

Low carbon & Low alloy steels

Ar + CO2 20-50 CO2 Low carbon & Low alloy steels


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SOLID WIRES

1. Generally copper coated and available in 10-15Kg Spolls,pay-offs of higher capacity upto 1000Kgs. Marketed abroad

2. Standard sizes are 0.8mm, 1.2mm, 1.6mm

3. Typical welding 100-160A, 120-300A, 200-450A current

range4. Chemical composition of wire is to be generally designed for

alloying losses occurring in transfer of molten metal.

5. Layer winding of the wire in spool helps uniform feeding of

wire6. Solid wires may also have special de-oxidiser additions



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SOLID WIRES

6. Wires are generally classified based on its chemical

composition & deposit properties with specified gas.

7. Co2, ar + co2mixtures & ar + o2mixtures are normally used

shielding gases

8. Eminently suitable for down-hand position welding and

horizontal fillet welding

9. Limited application in thin sections (


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ADVANTGES & LIMITATIONS OF SOLID WIRE

ADVANTAGES LIMITATION

1. LOW-HYDROGEN DEPOSITS. 1. WELDER TRAINING IS

MORE CERITICAL

2. DEPOSITION EFFICIENCIES 2. WELD PARAMETER CONTROL

UP TO 95% CRITICAL FOR WELD QUALITY

3. INDIGENIOUS AVAILABILITY 3.LACK OF FUSION DEFECTS

IS GOOD MORE COMMON ON OUT OF

4.COST OF WIRE IS LOW POSITION WELD

5.PROCEDURE OF 4.LOW DEPOSITION RATES IN

MANUFACTURING SIMPLE OUT OF POSITION WELDING



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ELECTRODE

E R X X S - X

ELECTRODE or RODTENSILE STRENGTH SOLID IMPACT VALUES

IN KSI or COMPOSITE & TEMP



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ER 70 S - 6

ER ELECTRODE or ROD

7070,000 PSI TENSILE STENGTH

SSOLID

6 - 27 J @ -290C



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CHEMICAL COMPOSITION

ER70S-G NO CHEMICAL REQUIREMENTS


C Mn Si P SER70S-2 0.07 0.90-1.40 0.04-0.70 0.025 0.035

ER70S-3 0.06-0.15 .090-1.40 0.15-0.70 0.025 0.035

ER70S-4 0.07-0.15 1.00-1.50 0.65-0.85 0.025 0.035ER70S-5 0.07-0.19 0.90-1.40 0.30-0.60 0.025 0.035

ER70S-6 0.07-0.15 1.40-1.85 0.80-1.15 0.025 0.035

ER70S-7 0.07-0.15 1.50-2.00 0.50-0.80 0.025 0.035


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NON FLUX CORED ARC WELDING



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ADVANTAGES OF FCAW

High quality weld metal deposit Excellent weld appearancesmooth, uniform welds

Excellent contour of horizontal fillet welds.

Many steels weldable over a wide thickness range.

Relatively high electrode deposit efficiency

Less precleaning required than GMAW

Reduced distortion over SMAW

High tolerance for contaminants that may cause weld cracking.



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LIMITATIONS OF FCAW

FCAW is presently limited to welding ferrous metals & nickel

base alloys.

Process produces a slag covering which must be removed

FCAW filler wires are more expensive than solid wires

More smoke & fumes are generated [Compared to GMAW &

SAW]



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ELECTRODE

E X X T - X

USABILITY

ELECTRODE & PERFORMANCE

TENSILE STRENGTH WELDING FLUX CORED

IN KSI POSITION



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CARBON STEEL ELECTRODE

E 71T-1

EELECTRODE

770,000 PSI TENSILE STRENGTH

1ALL POSITION

TFLUX CORED

1MULTIPASS



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FLUX CORED WIRES

1.SEAMLESS 2. SEAMED1. Generally seamless wires are copper coated & Seamed wires

have protective coating

2. Available in 10-15kg Spools & possible to procured in larger

weights3. Standard sizes are 1.2mm, 1.6mm, 2.4mm.

4. Flux in the core aids in protection of molten Metal, purifying

& refining molten metal & alloying

5. Layer winding in spools is desired to ensure uniform feeding6. CO2, Ar + CO2& Ar + O2Are normally used gases



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FLUX CORED WIRES

7. Flux cored wires are classified based on chemical

composition & mech. Properties of weld deposit & usability.

8. Eminently suitable for down hand position welding.

9. Special products ideally suited for out-of position welding areavailable.


FLUX CORED ELECTRODES


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FLUX CORED ELECTRODES



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GTAW PROCESS



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ADVANTAGES OF GTAW PROCESS

1. It produces superior quality welds, generally free of defects

2. It is free of spatter which occurs with other consumable arc

welding processes

3. It can be used with or without filler metal as required for

specific application.

4. It allows excellent control of root pass weld penetration.

5. It can produce inexpensive autogenous welds at high speeds.



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ADVANTAGES OF GTAW PROCESS

6. It can use relatively inexpensive power supplies.

7. It allows precise control of welding variables.

8. It can be used to weld almost all metals, including dissimilar

metal joints.

9. It allows segregation of heating & filler metal addition thereby

affording a greater freedom for the welder to control weld pool.



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LIMITATIONS OF GTAW PROCESS

1. Deposition rates are lower than the rates possible with

consumable electrode arc welding processes.

2. There is need for slightly more dexterity and welder

coordination than with SMAW & GMAW for manual welding.

3. The process is less economical to higher thickness& hence is

restricted to root runs only in most cases except where alternate

welding processes are not practical due to the nature of

materials.

4. Difficulty in shielding the weld zone properly in draftyenvironments.



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POTENTIAL PROBLEMS OF THE PROCESS

1. Tungsten inclusions can occur if the electrode is allowed to

contact the weld pool.

2. Contamination of the weld metal can occur if proper shieldingof the filler metal by gas stream is not maintained.

3. There is low tolerance for contaminants on filler or base metals.

4. Possible contamination or porosity is caused by coolant leakage

from water-cooled torches.



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TUNGSTEN ELECTRODE

Electrodes are classified on the basis of their chemical compositions

as specified in the table given in next slide and colour code

identification systems for various classes are also given.

Electrodes are produced either to clean finish or ground finish.

Electrodes with a clean finish have been chemically cleaned to

remove surface impurities after the forming operation. Those with a

ground finish have been centerless ground to remove surface

impurities


TUNGSTEN ELECTRODE


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TUNGSTEN ELECTRODE


AWS

CLASSIFICATION

COLOUR ALLOYING

ELEMENT

ALLOYING

OXIDE

WT.OF

ALLOYING

OXIDE %

EWP Green - - -

EWCe-2 Orange Cerium CeO2 2

EWLa-1 Black Lanthanum La2O3 1

EWTh-1 Yellow Thorium ThO2 1

EWTh-2 Red Thorium ThO2

2

EWZr-1 Brown Zirconium ZrO2 0.25

EWG Gray Not

specified

- -

CHARACTERISTICS OF CURRENT TYPES


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CHARACTERISTICS OF CURRENT TYPES

FOR GTAW


02abg slides weld proc

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