Cause: Incorrect Materials or Coatings

The material to be welded has a different base chemistry, processing, or coating than that specified for the part.


The metal type and coating have a large affect on weldability. Any of the following conditions may require weld schedule changes:

  • Substitution of any material by another that has different base metal characteristics (such as base metal chemistry, hardness, or processing).
  • Substitution of a coated steel (electrogalvanized, hot dip galvanized, or galvannealed) for another steel with the same base metal, but a different coating material or thickness.
  • Substitution of a bare steel (no coating) for a coated steel, or vice versa.
  • Substitution of a plated steel part for a coated or unplated part, or vice versa.

The above considerations should also be applied to aluminum and its coatings (conversion coatings, etc.).


Detectable evidence may include:


Quality, Workplace Issues, Cost, Downtime, Maintenance, Throughput (cycle time; PPH), are all potentially affected by this condition. Special considerations are noted below:

Cost: Substitution of an incorrect metal and/or coating can affect all of the welds made on the part, so weld repair may be extensive or require scrapping of the parts.

Subordinate Causes

  • Material substitution not reported throughout process/plant
  • Substitution necessary because of a shortage of the specified material
  • Parts erroneously made of the incorrect material
  • Parts have been plated because of corrosion concerns
  • Parts should have been plated, but this step was erroneously omitted

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