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ELECTRIC ARC WELDING

ELECTRIC ARC WELDING. DEEPAK-KUMAR C4902A-07. Introduction. Electric arc welding. A group of fusion welding processes that use an electric arc to produce the heat required for melting the metal. Electric arc is about 9,000

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ELECTRIC ARC WELDING

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  1. ELECTRIC ARC WELDING DEEPAK-KUMAR C4902A-07

  2. Introduction Electric arc welding • A group of fusion welding processes that use an electric arc to produce the heat required for melting the metal. • Electric arc is about 9,000 • All fusion welding process have thee requirements. • Heat • Shielding • Filler metal • The method used to meet these three requirements is the primary difference between arc welding processes.

  3. Arc Welding Requirements Filler Material Process Heat Shielding Stick Electrode SMAW Inert Gas (Flux) Electric Arc Electric Arc Inert Gas (Cylinder) Wire Electrode GMAW

  4. Arc Welding Power Supplies • The current for arc welder can be supplied by line current or by an alternator/generator. • The amount of heat is determined by the current flow (amps) • The ease of starting and harshness of the arc is determined by the electrical potential (volts). • Welding current adjustments can include: • Amperage • Voltage • Polarity • High frequency current • Wave form

  5. Five Common Output Currents For Arc Welding 1. AC (Alternating Current) 2. DC (Direct Current) 3. ACHF (Alternating Current-High Frequency) 4. PC (Pulsed Current) 5. Square wave

  6. TYPES OF JOINTS Five (5) joints: Corner Butt Lap Edge T

  7. 1. Surface Welds • Surface welds are welds were a material has been applied to the surface of another material. • May or may not be blended with the work piece. • Two common applications are for hard surfacing and padding.

  8. 2. Groove Welds Groove welds are used to fuse the sides or ends of two pieces of metal. The primary use of groove welds is to complete butt joints.

  9. 3. Fillet Welds Fillet welds have a triangular cross section and are used to fuse two faces of metal that are at a 90 degree angle to each other. Lap Joint Outside Corner T Joint

  10. Joints, Welds & Positions Arc Welding Positions Flat Horizontal Vertical Up Vertical Down Overhead

  11. Weld Nomenclature Bead Penetration Base metal Reinforcement Joint Angle Bead Root Face Excessive Penetration Root Opening

  12. Weld Nomenclature-cont. Reinforcement Toe Face Throat Leg Toe Root Leg

  13. Common Defects and Causes Description Cause(s) Excessive heat Excessive speed. The depth of the weld is less than specifications. The weld metal is not completely fused to base metal or passes are not completely fused. Incorrect angle Incorrect manipulation Insufficient heat Weld material flows over, but is not fused with the base metal. Slow speed

  14. Common Defects and Causes--cont. Description Cause(s) Weld bead does not extend to the desired depth. Low heat Long arc Incorrect joint design Small indentions in the surface of the weld • Excessive gas in the weld zone. • Moisture • Rust • Dirt • Accelerated cooling Small voids throughout the weld material.

  15. Common Defects and Causes--cont. Description Cause(s) Usually visible cracks on the surface or through the weld Accelerated cooling Constrained joint Small weld volume Cracks in the transition zone between the weld and base metal Induced hydrogen Incompatible electrode or wire Accelerated cooling Misshapen and/or uneven ripples Inconstant speed Incorrect manipulation Incorrect welder settings

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