ASM Online Member Community

Good afternoon to all members and I am reaching out to see if someone has a good visual interpretation of an inclusion that is visible to the naked eye. I have some microscopic images but I am trying to create a visual aid for our floor personnel to give a quick determination of a suspect nonconforming product. We are a high production induction heat treat operation so the visual picture / aid will allow us to at least raise the red flag for employees around the clock. It will allow us to at least contain the product until a more precise determination can be assessed with a team effort.

We run a low carbon steel bar in the 1043 range but any good image at this point will be beneficial.

Thanks again as always for all your support! 

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Rodney Recore
Plant Process Metallurgist
Brunner International
Gasport NY
(716) 998-9823
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Rodney,

It is best if you have the bar to take your own photos of what you are seeing as each steel looks a little different after heat treating.  If you have the other side of the piece that you took micro images of or even if you could break the mount sample out and take a phot of that you might have a useful training aid for the operators on the floor but I would not place to much faith in visually catching discontinuities in the steel before or after heat treating.  If you can I recommend liquid magnetic particle testing on a wet bench with UV light for the suspect material after heat treating.  I known that occasionally a near surface defect will heat-up different and I have heard of operators being able to identify suspect parts by how they heat up, but I would want a secondary step like running liquid magnetic particle testing on a wet bench to determine if all the parts in the run were affected.  If you still have your micro etched sample it could still be useful to ge a macro photo if you break the mount open?

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David Lammers
Engineer
Total Component Solutions
Sioux Center IA
(712) 451-6646
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Dear Rodney,

The same steel bar may have a different microstructure as depending on the heat treatment it has undergone prior to the metallographic observation. Annealing, Normalizing, Spheroidizing each yield a different microstructure, especially if the bar has a medium-large diameter. Inclusions inspection calls for a detailed metallographic analysis to obtain the proper inclusion classification. Therefore, no visual inspection can be done.

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Donato FIRRAO FASM
Professor
Politecnico di Torino
TORINO
+393351494032
Italy
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I would not be hung up on terminology like whether it is an inclusion for the reasons the others outlined. You have a suspect indication. Ordering standards will often include statements regarding allowable visible surface defects; you should look at those and act accordingly.Is it allowable? What are your your standards for allowable surface indications? Is the acceptable size less than what you can see with the naked eye? If yes, have you set up inspections such as mag particle as has been outlined? 

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Aaron Tanzer
Principal Research Engineer
University of Dayton Research Institute
Beavercreek OH
(407) 247-9557
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