Need help with very strange phenomenon

[RicoRider]

We have had some issues with scratches in a black oxide surface on a steel part. During investigation we discovered a very strange phenomenon at the bottom of some of the scratches. See attached picture. It's a pattern of perfect rows of dots/holes with a spacing of approximately 8 microns in both axes. One pattern is 15x15 dorts and the other 13x9. According to the laboratory these may be imprints from some kind of tooling or measuring equipment. This may be the wrong forum for this question, but maybe someone has seen something similar.

Thanks in advance!

 

[rke[pler]

Not a lot of detail in the images, so kind of spitballing here. I can't think of too many machining processes that would leave that kind of mark at the bottom of a hole, mechanical processes would be hard pressed to leave an orderly pattern of holes .0003" apart. That sort of looks like crystalline lattice but seems way too coarse for that.

 

[WizardOfBoz]

Look like laser-drilled holes. Is this a part you machined? Where did you get the material?

 

[PeteM]

Possibly laser marking of the material for traceability? Sometimes used to follow a batch of material through heat treat etc.

A black oxide treatment after might not have adhered???

 

[boslab]

Was the metal from Roswell?
Mark

 

[Admin5]

Closed due to meaningless topic title