module 3a

Module 3Metal Joining andCutting Processes

ASCENT INTERNATIONAL TRAINNIG

Welding Process Knowledge - A Benefit to InspectorsHelps spot problemsLeads to better inspectionGains respect of weldersGains cooperation


WIT Coverage of Welding ProcessesAdvantagesLimitationsEquipmentFiller MetalsTechniquesProblems


3 Basic Process GroupsWeldingBrazingCutting


Weldment ASCENT INTERNATIONAL TRAINNIG

Common Features of Welding ProcessesSource of energySource of shieldingFiller metal (optional)


Shielded Metal Arc Welding(SMAW) ASCENT INTERNATIONAL TRAINNIG

SMAW ASCENT INTERNATIONAL TRAINNIG

E X X X XSMAW Electrode dentification System Electrode


E X X X XSMAW Electrode Identification System Strength


E X X X XSMAW Electrode Identification System Position


Position Description1 - used in all positions2 - used in flat or horizontal fillets only3 - not used at present time4 - used for downhill progression


E X X X XSMAW Electrode Identification SystemCoating/Operating Characteristics


Electrode Coating ClassificationF #s - Figure 3.4, page 3-5F1 - EXX20, EXX24, EXX27F2 - EXXX2, EXXX3, EXXX4F3 - EXX10, EXXX1F4 - EXXX5, EXXX6, EXXX8


Low Hydrogen ElectrodesTypes end in a 5, 6, or 8Purchase in sealed, metal containersStore after opening in heated, vented ovenLimit atmospheric exposure


Electrode Suffixes - 1 of 2 ASCENT INTERNATIONAL TRAINNIG

- A1

0.5% Mo

- B1

0.5% Mo; 0.5% Cr

- B2

0.5% Mo; 1.25% Cr

- B3

1.0% Mo; 2.25% Cr

- B4

0.5% Mo; 2.0% Cr

- W

Weathering

Electrode Suffixes - 2 of 2 ASCENT INTERNATIONAL TRAINNIG

- C1

2.5% Ni

- C2

3.5% Ni

- C3

1.0% Ni

- D1

0.3% Mo; 1.5% Mn

- D2

0.3% Mo; 1.75% Mn

- G

0.2% Mo; 0.3% Cr; 0.5% Ni;

1% Mn; 0.1% V

Stainless Steel ElectrodesE308, E308L - Weld 304 and 304L E316, E316L - Weld 316 and 316LE309 - Weld Stainless to Carbon Steel


SMAW Equipment ASCENT INTERNATIONAL TRAINNIG

Constant Current Power Source ASCENT INTERNATIONAL TRAINNIG

Constant CurrentAs arc voltage, V, drops, arc current, A, risesArc V related to distance from electrode to workElectrode moved closer, Arc V falls, Arc A risesElectrode moved away, Arc V rises, Arc A dropsArc current directly related to heat inputWelder controls heat input to work


SMAW AdvantagesSimple equipmentInexpensiveVery portableWelds most alloys


SMAW LimitationsRelatively slowSlag removalElectrode storage considerationsArc blow- solutions noted in text


Magnetic Aspects of Current Flow ASCENT INTERNATIONAL TRAINNIG

Arc Blow ASCENT INTERNATIONAL TRAINNIG

SMAW DiscontinuitiesPorositySlag inclusionsSpatterIncomplete joint penetrationIncomplete fusion


Gas Metal Arc Welding (GMAW) ASCENT INTERNATIONAL TRAINNIG

GMAW Schematic ASCENT INTERNATIONAL TRAINNIG

E R X X S - XGMAW Electrode Identification SystemElectrode


E R X X S - XGMAW Electrode Identification SystemRod(Designation used also for GTAW filler)


E R X X S - XGMAW Electrode Identification SystemStrength


E R X X S - XGMAW Electrode Identification SystemSolid Wire


E R X X S - XGMAW Electrode Identification SystemChemical Composition


GMAW Equipment ASCENT INTERNATIONAL TRAINNIG

GMAW Nomenclature ASCENT INTERNATIONAL TRAINNIG

Constant Potential Power Source ASCENT INTERNATIONAL TRAINNIG

Constant Potential SourceIs self-regulating (maintains constant arc length)Reduces effect of vertical movement of gunLess operator sensitiveSomewhat easier to learn


GMAW Modes of Transfer -1 of 4Spray ASCENT INTERNATIONAL TRAINNIG

GMAW Modes of Transfer - 2 of 4Globular ASCENT INTERNATIONAL TRAINNIG

GMAW Modes of Transfer - 3 of 4Pulsed Arc

The welding current is variable; it is pulsed between high and low current cycles set by the welder


GMAW Modes of Transfer - 4 of 4Short-Circuiting Transfer ASCENT INTERNATIONAL TRAINNIG

Factors for Transfer ModesShielding gasCurrent levelVoltage levelPower supply


GMAW AdvantagesSemiautomatic processHigh productivityNo slag to removeClean processContinuous filler metal feedWelds most alloys


GMAW LimitationsUnsuitable for windy conditionsLittle tolerance for contaminationUsually limited to shop weldingEquipment is more complexConsumables - liners, contact tips


GMAW DiscontinuitiesPorosityIncomplete fusionIncomplete joint penetration


module 3a

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