Here’s a puzzle; maybe some of my readers can figure it out.
My wife showed me a tiny pinhole that appeared in one of our stainless steel pots. How did this happen? What mechanism could have created the hole?
I took one look and said “cosmic ray hit”. But I was joking.
The pot is a few years old, but has never been used for anything unusual – just a little cooking and storage of food in a fridge.
The hole is just above the penny – you can see the light shining thru it (click on the image for a larger version).
It’s fairly thin steel; about half a millimeter.
Here’s a close-up photo of the hole from the inside:
The hole is about 0.2 millimeters in diameter (the crater is larger).
Here it is from the outside:
So it looks like whatever happened started from the inside.
What did happen?
#1 by Bob Alexander on 2011 December 25 - 20:32
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I would guess a micrometeorite impact.
Googling for holes in stainless steel, I get mostly info about drilling a hole. Apparently, it’s a challenging thing to do. So I don’t think an ordinary kitchen-environment impact would do this.
Another thought I had was a manufacturing defect where there was an air or water bubble inside the metal. Repeated heating and freezing might’ve done it. But my daughter points out that a bubble would probably break through one surface instead of both (smart kid). And although I don’t know the details of making a stainless steel bowl, I imagine it involves extremely high heat and molten steel. I don’t know how a water bubble would form in those conditions.
#2 by Fred Buls on 2012 June 16 - 22:01
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The second idea above is what first occurred to me: a little cavity containing water or some other material that would pressurize under heating. But if the bowl was made by pressing steel into a form, it could be that a foreign object was pressed into it and this eventually came loose.
Love your rocket project. I envy you your electronics knowhow, because I found this site when looking for info on flyback model rockets.
#3 by Mike on 2012 July 22 - 11:41
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Try Googling “why stainless steel sink pitting” and I think you will come up with an explanation. I found a couple of pinholes in my stainless steel laundry sink, and it appears that the pinholes are a result of the pitting going further. I never knew stainless steel corroded, but apparently chlorine and food acids not good for ss.
#4 by john arul on 2013 March 18 - 07:42
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It is likely due to pitting corrosion is SS.