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Welding Processes Overview

Shielded Metal Arc

Gas Metal Arc

Gas Tungsten Arc

Submerged Arc

Plasma Arc Oxy-Fuel

Laser Beam

Miscellaneous

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Shielded Metal Arc Welding - SMAW

(Stick welding)

AC or DC

Consumable Electrode

Constant Current

Current Range =30 A -

600 A

Covering may havemetal, shielding gas,

arc stabilizers, and

slag formers

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SMAW (cont)

Advantages

Low capital expense

Portable

Can weld in all

positions

Better shielding in

windy locations thangas-shielded processes

Can weld dirty metal

Disadvantages

Shielding not sufficient

for reactive materials Low deposition rate (2-

17 #/hr.)

Possibility of slag

inclusions, defects Stub losses (1-2 of

every 14= 7%-14%

waste

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Gas Metal Arc Welding - GMAW

(Mig Welding)

Consumable Electrode

Primarily DC

Constant Current (CC) /

Constant Voltage (CV)

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GMAW (cont)

Advantages

Higher deposition rate

(1-30 #/hr.) higher current density

than SMAW = better

penetration

Less operator skillrequired

Higher efficiency

All positions

Most metals weldable

Disadvantages

Higher capital cost

than SMAW Shielding gas required

wire can bird-nest

(Al wire in particular)

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Gas Tungsten Arc Welding - GTAW

(Tig Welding)

Nonconsumable

electrode

Constant-Current

AC or DC

Gas shielded - AR,

He, or Ar-He mix Hi-freq often used

cold-feed or hot-feed

wire

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GTAW (cont)

Advantages

Suitable for ALL

metals Suitable for very thin

materials (i.e. coke

cans)

Allows very precisecontrol of weld

Disadvantages

Typically very slow travel

speeds Hi equipment costs

10-20% as fast as GMAW

Higher skill required

(OFW experience helpful)

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Submerged Arc Welding

Consumable Electrode

Primarily DC

Constant Current (CC) /

Constant Voltage (CV)

Arc completely covered

by granulated flux Primarily automated or

semi-automated

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SAW (cont)

Advantages

90%-99% Efficiency

Very high depositionrate

Excellent penetration

Alloying can be

controlled through fluxcomposition

flux may be recycled

Disadvantages

Flat and horizontal

positions only Not suitable for thin

material

Uses roughly 1# of

flux per pound ofelectrode

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Plasma Arc Welding (PAW)

Melt-in and keyhole

welding methods

DCEN/DCEP/AC

Pilot arc initiates main

arc (30,000 plasma)

cold-feed or hot-feedwire

Ar used for plasma

Ar, He, Ar-He, Ar-H

used as shielding gas

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PAW (cont)

Advantages

Can weld VERY thin

material -- 0.001 Higher welding speed,

improved arc stability,

higher heat content ->

greater penetration All metals, all positions

Disadvantages

High capital cost

High maintenance cost More complex welding

procedures

More operator training

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Process Efficiencies

Submerged GTAW

can approach 99%

EBW range = 80-95%

LBW varies widely:

2% - 98% depending

on material reflectivity

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Miscellaneous Processes

Ultrasonic Welding - USW

Electron Beam Welding - EBW

ElectroSlag Welding - ESW

Explosion Welding - EXW

Friction Stir Welding - FSW Flash Welding - FW

And over a 100 other processes...