Incorrect Material/Coating

Definition

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

Description

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.)

Detection

Detectable evidence may include:

Significance

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, and, in the worst case, 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