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Arc Welding Processes. 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
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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
Linnert, Welding Metallurgy, AWS, 1994
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
Linnert, Welding Metallurgy, AWS, 1994
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
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
Shielding Gas • Shielding gas forms a protective atmosphere over the molten weld pool to prevent contamination • Inertshielding 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