rust caracterisation

[Fred]

We are frequently questionned about red coloration of parts : is it rust or only a coloration of a residual product like oil or temporary protection or anything else?

Today, we examine the parts with a magnifying device to see if the "rust" begins to dig the metal

Does anybone know an easy test (chemical?) to qualify this coloration?.

 

[unclesyd]

What material are the parts made from?
Are you talking about a finished surface?
What is the enviroment the parts are in?

If the parts are carbon steel and have a finished, machined, or ground you more than likely have "flash rust".
This normally a visual determination though a piece of transparent tape applied and removed should show if it is rust. I not aware of any test that will detect iron on iron.

 

[Fred]

The problem is general : parts obtained by fine blanking, laser cutting, machining....
The material is carbon steels or HLE (high elastic limit),...
The environnement is "normal" environnement of stockage : ambiant temperature inside

 

[stanweld]

Fred,
Rusting of carbon steels must be expected during storage as you have indicated. Application of light oil films or thin coatings will provide greater protection during storage but will not preclude rusting over time.

 

[unclesyd]

Don't use lubricating oils.
Check with a local chemical cleaning supply store or petroleum products supplier and see if they have a
rust preventive oil. If the parts are high value added parts you will have to use special products sometimes call metal protecting compounds or you may be able to use special treated paper wrappings.

 

[Fred]

Thank you for your advices. We use these kind of products either between operations and on the final parts. But the problems occur at subcontractors or on raw materials.... That's why we need a mean to confimr or not the presence of rust and a curating method when the rust presnce is confimed.