Material Identification.

Even if we say yes, the customer still might not be satisfied. Thus I would ask them first.

Are the SAE 1018 screws nickel plated; is their Cr content ≥ 16%?

Yes, they are ni plated!

thanks

Tell them we said it's OK, and we guarantee it.

I prefer your big red "approved" stamp!...then again it's good to have a selection depending on the occasion.

Well,

There's a big difference between "APPROVED" and "GUARANTEED".

Can't have any confusion.

Oh, here's one..."CR4 Certified". Rolls off the tongue quit nice. LOL!

I'm retired and don't have my technical books near me, but isn't 16% Cr a corrosion resistant steel, not a low carbon one? Or am I getting to out-of-date for my own good?

You're right.

I think there is a misinterpretation of which is in turn a bad specification.

I would bet my left kidney (One surgeon take it some time ago) that the customer requirements are for a stainless steel (if Cr>16% is a stainless) with low carbon content or "L grade" such as 304L, 316L, etc. Surely the words "low carbon" meaning is that, otherwise the customer has no idea about what a steel is!!!

Kind regards

I think the chrome content has to do with both corrosion and hardness.

Unless you are supplying to really high-tech industry, it is unlikely that the customer deveoped the material spec in-house. They probably specified something that is available in the market place, or they may actually know a supplier....

Time to embarrass yourself and ask your customer ...

I don't believe there is any embarrassment in asking the customer to clarify what he wants, especially with a specification that is not clear. The real concern is how to ask without embarrassing the customer for publishing a poorly-written spec.

Frankly, I think whoever put out the spec didn't understand what they were asking for. No wonder you're confused.

Yes, it is true that a steel with >16% chromium is a 300-series stainless steel, not 1018 carbon steel. The 16% chromium content doesn't apply to the nickel plating...by definition, that's nickel. And it's also true that the carbon content in 300 series L grade steels is low....but why specify this for fasteners? Usually L grades are specified for weldabiity and machinability, although corrosion resistance might be a concern. However, if the difference beteen plain and L grade stainless makes that much difference, another material with even higher corrosion resistance might be a better choice.

CHQ-1018 It stands for :Cold Headed Quality ,Grade;1018, Al. killed definition-not enough,you need a low content of S+P and VD Quality steel

I suspect your customer is confused. While 1018 is indeed a low carbon steel, it doesn't contain more than trace amounts of chromium and it is not commonly used to for fasteners because of its relatively low strength and because it is not heat treatable.

The screws are for used in a led light tube that is being used in a NSF approved food vending machine, and thats why the call for min Chromium content of 16%. Chromium helps in the resistance of corrosion.

Yes, I understand that chromium content is for corrosion resistance but the spec is confusing....1018 low-carbon steel does NOT contain 16% chromium, nor does the nickel plating.

I checked McMaster-Carr for comparison, and they sell a chrome-plated 18-8 stainless steel screw, or cadmium plated steel screw, but do not list a chrome-plated steel screw. It might be a specialty item and therefore expensive.

The plated stainless steel screw is roughly twice the cost of a plated steel screw, but for use in food industry machines, I'd recommend the stainless steel over carbon steel plated or not. Cadmium was at one time considered a carcinogen and was not approved for use in food or drug machinery where product contact might occur, so that leaves it out. If the client still insists on 16% chromium simply go to 18-8 stainless steel fasteners which have 18% chromium and 8% nickel. That's equivalent to 304 and 316 stainless steel and you can find fasteners almost anywhere to that spec. Go with 316 and you probably do not need any plating at all, as 316 in product contact is used just about everywhere in food and pharmaceutical manufacture.

I think you should go back to your client and discuss what they really need and what's avaiable at reasonable cost while still satisfying industry specs.