Wrong Corrosion Test Method for 420SS Knife Blades? 4

[hlin88]

Wrong Corrosion Test Method for 420SS Knife Blades?

We send cutlery set samples ( kitchen knives ) to a testing for corrosion testing, but it failed. The knife blade is made of 420 stainless steel with heat treatment. The testing service uses salt water spray chamber to do the corrosion testing for 24 hours; big percentage of rust and pitting appear on knife blades after testing. I think salt water spray chamber is not the right corrosion testing method for cutlery knife blade, since the knife blade is made of 420 stainless steel which is higher carbon content with less corrosion resistance. What is the right method to do corrosion test for knife blade ? Where can I find the correct test method ? please advise.

Thanks for the help.

Andy
andylin@wingar.com

 

[unclesyd]

I agree with you that the salt spray test is a little to extreme for a kitchen knife. It had been several years since I looked a knives/blades in respect to corrosion and I don't remember any knife being subject to a salt spray, even diver's knives. The biggest factor in corrosion or pitting on kitchen knives is food left on the blade, even for short period. I don't know how you would scientifically test for this.

A good source of information might be Consumer Reports magazine, they test everything else.

There was also some tests that 420 SS scalpels had to pass, but if I remember correctly it was autoclave and detergent/sanitizer compatibility.

I'll look around and see if I have any info left.

 

[tomwalz]

There is a corrosion society through the ASM

The corrosion person I know best is Margaret Ziomek-Moroz moroz@alrc.doe.gov

Her work is very good - not sure if this is her area but she could refer you on.

Tom

 

[metengr]

hlin88;
Since these are cutlery knives, I would use the following web site for information. The NSF (National Sanitary Foundation) will provide corrosion testing guidance to qualify your material for use. Their seal of approval is as good as gold in food service.

http://www.nsf.org/

 

[israelkk]

Federal standard QQ-P-35 (for militaty use of stainless steels passivation) requires only two hours test in 5% salt spray of pasivated stainless steels parts.

 

[hlin88]

Thank you for all your reply. We sent the kitchen knife samples to ITS ( Intertek ) which is also big testing lab company. I have to find the right international standard of corrosion testing standard to prove that the 24 hour salt water spray chamber corrosion testing is not the right way for cutlery blade. Thanks.

 

[edrush]

The worst enviornment your knife might see is probably the dishwasher. I am amazed at how an aluminum ice cream scoop has corroded in our dishwasher. You might want to take one home and leave it in the dishwasher for a month or two (assuming you do a load of dishes every day) as a field test.