Welding: defects and discontinuities

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Welding: defects and discontinuities
2013-10-01 23:16:51

SMAW Defects and Discontinuities study guide
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  1. A Defect is:
    A flaw or imperfection determined to be defective by a welding code or welding specification.
  2. A Discontinuity is:
    A flaw or imperfection in a weld (has tolerances)
  3. Porosity is:
    • Trapped gas
    • Discontinuity
  4. Porosity is caused by:
    • -Excessive arc length
    • -Contaminated base metal
    • -Moisture in a low hydrogen electrode or the  base metal
  5. Inclusions:
  6. Inclusions are caused by:
    • Improper bead placement
    • Improper grinding of the rot pass/ slag trapped at the tows of the weld
    • Allowing the slag to run in front of the weld as it is being deposited
    • Improper inter-pass cleaning
  7. Undercut is:
    • Occurs at the toes of the weld when the base metal is cut out by the arc and not replaced
    • Discontinuity
  8. Undercut is caused by:
    • Excessive welding parameters/ amperage
    • Improper electrode angle
  9. IP (Inadequate Joint Penetration) is:
    • Depth of fusion is insufficient.
    • Defect
  10. IP (Inadequate Joint Penetration) is caused by:
    • Poor fit-up/ High low/ Root opening too small
    • Improper technique / arc length
    • Found on the root face
    • Amperage too low
    • Improper electrode angle
    • Improper travel speed
  11. Arc strikes are:
    • when the electrode touches the base metal and initiates the arc outside the weld zone.
    • Defect

    (The arc strike rapidly heats and cools a small area of the base metal making it brital)
  12. Overlap is:
    • Occurs at the toes of a weld when the filler metal flows over the base metal without fusing to it.
    • Defect
  13. Overlap is caused by:
    • Improper bead placement
    • Excessive amperage
    • Improper angle
  14. Cracks are:
    • Base metal crack and throat cracks
    • Defect
  15. Cracks are caused by:
    Welding base metal at temps below 32 F (recomended 70 F or more)

    WElding codes stipulate specific preheat temperatures for base metals exceeding 3/4 inch

    incompatible base metal to filler metal

    Crater crack caused by improper termination of the weld.
  16. Under fil is:
    When the height of the filler metal is below the required weld size.

  17. Under fill is caused by:
    • Improper bead placement
    • Improper welding technique
  18. Non Fusion (#1)
    • Defect
    • Improper bead placement
    • Poor or improper fit-up
    • Poor welder skill
    • Improper welding parameters
  19. Excessive Convexity is:
    At the root face/ back side of the root pass. The weld is over filled on the backside of the root pass.

  20. Excessive  Convexity is caused by:
    • Excessive parameters
    • Improper preparations/ Land too thin
    • Improper fitup/ root opening to largs
    • Excessice arc length
    • Improper electrode angle
  21. Excessive  Concavity is:
    At the root face/ back sidde of the root pass. The weld is under filled on the back side of the root pass.

  22. Excessive Concavity is cause by:
    Excessive arc length/ electrode not deep enough.
  23. Excessive weld reinforcement is:
    height of the filler metal exceeds 1/8" above required weld size

  24. Excessive weld reinforcement is caused by:
    • Travel speed too slow
    • Improper bead placement size
    • Excessive paameters
  25. Discontinuities:
    • Porosity
    • Slag Inclusions
    • Undercut
    • Concavity
    • Convexity
  26. Defects:
    • Non-fusion
    • under fill
    • Excessive weld reinforcement
    • Excessive concavity
    • Excessive convexity
    • Cracks
    • Overlap
    • Arc Strikes
    • Inadequate Joint Penetration/ IP