440A - ASTM A276 vs. F899 Certification? 1

[BiPolarMoment]

At my last company ~5 years ago we specified most if not all of our stainless instrument materials "per ASTM F899" as that is a blanket specification that includes such specifications as A276, A484 et. al. As far as I am aware, the chemical requirements of F899 are identical to those of the referenced specification with a few exceptions (I don't believe 440A is one of them). I don't remember ever having trouble getting parts quoted/produced back then.

Now at my current company we have an internal specification for some materials (e.g. 17-4) but 440 is not one of them. Since I don't have an internal specification to cite I've gone back to referencing F899. However, now I'm getting notice from vendors that they are not able to source that material unless they buy a considerable minimum qty which is no good for price or time. In the short term I've been able to get around this by agreeing the material certified to A276 is "compliant" to F899 and is therefore acceptable.

I admit there is probably an additional burden to certifying to F899 but I'm not sure what it is; and that doesn't necessarily explain the discrepancies in my experience. Can someone enlighten me? One vendor claimed that F899 required a vacuum melt vs. an airmelt for A276 but I've not been able to find where it says this.

The 'simple' solution is to spec A276 but I'd rather understand where the problem lies. It's possibly my memory, but I haven't admitted that yet.

 

[EdStainless]

You do own current copies of both specs, and any referenced general spec, right?
Since you are trying to invoke them as contract terms you have better make sure you have copies.

The F spec is medical grade material. It will have a cleanliness requirement. I don't know if it requires re-melting or vacuum melting but those may be needed to meet the cleanliness.

Read the spec.

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Plymouth Tube

 

[skailup]

This is sourcing and inventory issue. Part manufacturers would like flexibility to buy steels from any distributors- small but sufficient quantity at a time. Distributors will have steels certified to A276 most of the times. A276 is widely used whereas F899 is limited to surgical applications.

Relatively large distributors can re-certify the material if your company allows. They can either re-test or simply verify mill-cert properties against F899 and issue another certificate under their own name. Large distributors that have many medical-grade buyers or have long term agreements with such customers will have direct certification to F899 from mills. Few part suppliers are willing to certify the material by their own but rather rely on certs from mills or distributors.

Some implantable grade alloys may have cleanliness requirements. However, F899 is for surgical instruments (non-implantable) and do not have such requirements unless it is inherent to the grades. Fore example, there is melting requirement for 13-8 Mo but that is not regulated by F899. F899 instead imposes a narrower compositional range, mostly 0.01 % carbon difference, than what A276 requires in several grades. I do not know why and do not see benefit. I believe that 440A is fine and has no discrepancy.