Arc Welding Processes

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Arc Welding Processes
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Arc Welding Processes

• Lesson Objectives
• When you finish this lesson you will be able to
• Explain similarities and difference between some
  of the various arc welding processes
• Explain flux and gas shielding methods
• Explain advantages and disadvantages of the arc
  welding processes
• Select between the processes

• Learning Activities
• Read Handbook Pp 1-16,
• Look up Keywords
• View Slides
• Read Notes,
• Listen to
• lecture
• Do on-line workbook
• Do homework

Keywords Welding Flux, Inert Shielding Gas,
Shielded Metal Arc Welding (SMAW), Gas Metal Arc
Welding (GMAW), Metal Transfer Mode
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Linnert, Welding Metallurgy, AWS, 1994
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Arc Welding Processes

• Welding processes that employ an electric arc are
  the most prevalent in industry
• Shielded Metal Arc Welding
• Gas Metal Arc Welding
• Flux Cored Arc Welding
• Submerged Arc Welding
• Gas Tungsten Arc Welding
• These processes are associated with molten metal

Electric Arc
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Linnert, Welding Metallurgy, AWS, 1994
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Protection of the Molten Weld Pool

• Molten metal reacts with the atmosphere
• Oxides and nitrides are formed
• Discontinuities such as porosity
• Poor weld metal properties
• All arc welding processes employ some means of
  shielding the molten weld pool from the air

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Welding Flux

• Three forms
• Granular
• Electrode wire coating
• Electrode core
• Fluxes melt to form a protective slag over the
  weld pool
• Other purposes
• Contain scavenger elements to purify weld metal
• Contain metal powder added to increase deposition
  rate
• Add alloy elements to weld metal
• Decompose to form a shielding gas

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Shielding Gas

• Shielding gas forms a protective atmosphere over
  the molten weld pool to prevent contamination
• Inert shielding gases, argon or helium, keep out
  oxygen, nitrogen, and other gases
• Active gases, such as oxygen and carbon dioxide,
  are sometimes added to improve variables such as
  arc stability and spatter reduction

Argon
Helium
Oxygen
Carbon Dioxide