High Stress/Corrosion Resistant Stainless Steel for Food Environment
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Question

High Stress/Corrosion Resistant Stainless Steel for Food Environment

cb68 (Mechanical)

(OP)

5 Jul 03 13:34

Hi

I am operating in a wet / frozen food environment. I have a shaft application where 316L stainless steel is overstressed.
Some web research has turned up EN 1.4462/ASTM S32205/ASTM 31803/ASTM32203/2205 duplex stainless as a potential candidate.
It is hinted at that this duplex grade is more corrosion resistant than 316L and is used in food applications. Can anyone point me in the direction where some form of food approval for this material is available and also definitive corrosion results. Has anybody used this grade in a similar application.

mcguire (Materials) · Answer 1 · 2003-07-09 13:21:43

The National Santitation Foundation in Ann Arbor, MI issues the regs that all USA producers follow. In this case the regulation is that for any food contact zone  the stainless steel must have at least 16% chromium. All austenitcs and duplex meet this standard.
  In my experience 2205 has not been used in food equipment simply because its corrosion resistance and strength haven't been needed. Nor has its cost.
  The corrosion resistance of stainless is roughly equal to
%Cr + 3.3%Mo + 16%N
This shows that 2205 is well ahead of 316. Try AvestaPolarit's or Allegheny Ludlum's web sites for data and advice.
  316 can be cold-worked to high strengths. Have you considered that. At low temperatures neither corrosion nor stress corrosion cracking should be a problem unless your nevironment is really nasty.

boo1 (Mechanical) · Answer 2 · 2003-07-10 11:14:58

Consider 17-4 PH precipitation hardening alloy, or Nitronic xx.

cb68 (Mechanical) · Answer 3 · 2003-07-12 10:28:07

Thanks very much for the information. I've ordered the NSF Standard 51 for any future applications. As I'm not based in the US I didn't know this standard even existed.

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High Stress/Corrosion Resistant Stainless Steel for Food Environment
2