Shielded Metal Arc Welding SMAW

1
Shielded Metal Arc Welding SMAW
2
Shielded Metal Arc Welding (SMAW)
3
SMAW Electrode Classification Example

• E7018
• E indicates electrode
• 70 indicates 70,000 psi tensile strength
• 1 indicates use for welding in all positions
• 8 indicates low hydrogen

E7018-A1-H8R
4

• ANSI/AWS - 5.1 Specification for Covered Carbon
  Steel
• ANSI/AWS - 5.5 Specification for Low Alloy
  Steel
• ANSI/AWS - 5.4 Specification for Corrosion
  Resistant Steel

AWS Website http//www.aws.org
5
Coating Materials -Partial List
Slipping Agents to Aid Extrusion Clay Talc
Glycerin Binding Agents Sodium Silicate
Asbestos Starch Sugar Alloying and
Deoxidizing Elements Si, Al, Ti, Mn, Ni, Cr
Arc Stabilizers Titania TiO2 Gas-Forming
Materials Wood Pulp Limestone
CaCO3 Slag-Forming Materials Alumina Al2O3
TiO2 SiO2 Fe3O4
6
Linnert, Welding Metallurgy AWS, 1994
7
Linnert, Welding Metallurgy AWS, 1994
8
SMAW Advantages
Shielded Metal Arc Welding

• Easily implemented
• Inexpensive
• Flexible
• Not as sensitive to part fit-up variances

9
Advantages

• Equipment relatively easy to use, inexpensive,
  portable
• Filler metal and means for protecting the weld
  puddle are provided by the covered electrode
• Less sensitive to drafts, dirty parts, poor
  fit-up
• Can be used on carbon steels, low alloy steels,
  stainless steels, cast irons, copper, nickel,
  aluminum

10
Quality Issues
Shielded Metal Arc Welding

• Discontinuities associated with manual welding
  process that utilize flux for pool shielding
• Slag inclusions
• Lack of fusion
• Other possible effects on quality are porosity,
  and hydrogen cracking

11
Limitations
Shileded Metal Arc Welding

• Low Deposition Rates
• Low Productivity
• Operator Dependent

12
Other Limitations

• Heat of welding too high for lead, tin, zinc, and
  their alloys
• Inadequate weld pool shielding for reactive
  metals such as titanium, zirconium, tantalum,
  columbium