From your opinion, is it a closed pore or a hole made by corrotion?
From your opinion, is it a closed pore or a hole made by corrotion?
(OP)
This is my first case. I found this in the small size bearing on the face, on outer diameter of the bearing. The material is JIS based standard SUJ2 with 1,3-1,6 percent chrome. It is restricted from the company for publishin any other materials than this, so i want to know any other opinions about this defect. I hope this will continue into a good discussion. Thanks.





RE: From your opinion, is it a closed pore or a hole made by corrotion?
rp
RE: From your opinion, is it a closed pore or a hole made by corrotion?
RE: From your opinion, is it a closed pore or a hole made by corrotion?
what if the pores were made from the making of the steel from the foundry? Like the pores made from the bubbles of CO2? If the pores is deep in the steel, it need to be grinded to peel and reveal it, is it possible?
@TVP
it is the highest magnification in my lab, is it not good enough to interpret?
RE: From your opinion, is it a closed pore or a hole made by corrotion?
RE: From your opinion, is it a closed pore or a hole made by corrotion?
Have you tried to remvoe it with a fine abrasive such as scotchbrite or steel wool?
rp
RE: From your opinion, is it a closed pore or a hole made by corrotion?
Is it a hole? Could the hole represent part of a sphere?
I'd second the Scotchbrite suggestion.
Any chance it is a production or post production handling issue? Any information on the rate of occurrence? I have a pretty good list of things that occurred once over the years. Monday morning problems. Problems after a 3 day weekend. A sticky torch valve and so on.
In thirty years of consulting and teaching I have learned to recognize various facial expressions among my audience. One occurs when I explain why you shouldn't do something. I sometimes see a facial expression that very clearly says (Oh Sh--, I better quit doing that.)
Thomas J. Walz
Carbide Processors, Inc.
www.carbideprocessors.com
Good engineering starts with a Grainger Catalog.
RE: From your opinion, is it a closed pore or a hole made by corrotion?
RE: From your opinion, is it a closed pore or a hole made by corrotion?
the defect is found on in-house production, which means it never leave the company. The production line consist of lathing process from bar and tube material, heat treatment to make the double-temper martensitic structure, grinding + super finish, and assembly.
@TVP
Oh, okay, i`ll try to take picture on the cross section, i will post it on Monday.
@rp
when the defect occurs, it is founded in all production line in the my company. My mentor said those defect caused by the supplier of bar and tube steel, because they target a higher sell so they turn down the quality by speeding the process. I suspect rather void or the hole left by intemetallic compound. But i'm not sure...
The bearing is cleaned, not using scotchbrite, but using another brands, hehe....
but is it important? we didn't see any spalling after the cleaning...
@tomwalz
By my experience when training, it is hard to make an those kind of indentation with the machine. And the defect is not reciprocal, so i think it is not because the machine. Plus the black mark on the spot, i don`t think any machine in my company leave that trail...
i'll find any new information regarding this. Thanks mister. Wow, you have been teaching for 30 years? where have you been teaching?
@ron
yup, the lenses is clean =D
RE: From your opinion, is it a closed pore or a hole made by corrotion?
I want to ask your opinion, is it any possibilities of void from the casting process? if that so, how the void created? Is there any parameter that i have to consider about the steel-maker and supplier?
Thank you =D
RE: From your opinion, is it a closed pore or a hole made by corrotion?
Since these are all on the outside (I take it that you don't find them on the bearing surface) I doubt that it is the steel.
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Plymouth Tube
RE: From your opinion, is it a closed pore or a hole made by corrotion?
What is the base material form (tube or bar) exhibiting the pore-like surface?
RE: From your opinion, is it a closed pore or a hole made by corrotion?
Also, is this a as-cast part, forged, or cast and HIP? That surface looks either forged or at least peened.
RE: From your opinion, is it a closed pore or a hole made by corrotion?
RE: From your opinion, is it a closed pore or a hole made by corrotion?
If there is something wrong, in what process it will be?
@stanweld the material shape is bar for inner ring, and tube for outer ring, with SUJ2 (JIS standard), same with AISI 52100.
@metengr i have asked the lab to add adequate instrument for metallography, but no respond, sigh... =(
RE: From your opinion, is it a closed pore or a hole made by corrotion?
Why don't you send the piece out for proper analysis to another metallurgical lab? If this is important enough, it should be done.