316 SS RoHS Compliance

[phili22]

I have a general question about a 316 stainless steel part we will be fabricating that we require to be RoHS compliant for our customer's application. The RoHS directive restricts the use of certain hazardous substances to the following levels for stainless steel:

Lead – Pb 0.35%
Mercury – Hg 0.1%
Cadmium – Cd 0.01%
Hexavalent chromium – Cr (VI) 0.1%
Polybrominated biphenyls – PBB 0.1%
Polybrominated diphenyl ethers – PBDE 0.1%

In our drawing, we have specified 316SS as per ASTM spec A240 where the relative concentrations of alloying elements are described. However, for a lot of materials in that spec, there is a large concentration of "other" which is why I am concerned. For 316 stainless it is more than 50% by weight devoted to "other". How do I know that the "other" portion of the material is primarily iron and not a prohibited amount of mercury, cadmium or anything else prohibited by RoHS? Any help would be greatly appreciated.

 

[DennisP]

Unless I miss my guess, the other is probably iron as it is still a large part of the chemistry of stainless steel.

 

[EdStainless]

RoHS has no applicability to bulk Stainless alloys.
Unless you have been dry grinding or cutting and leaving dust on the parts that contains Cr+6.
There is no detectable Pb, Hg or Cd in stainless.

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Plymouth Tube

 

[MiketheEngineer]

Also iron is a WHOLE lot cheaper than any of the other materials you mentioned. Have a piece analyzed...

 

[phili22]

I do realize that the majority of "other" has to be made up of iron. My concern was that the iron may be contaminated with trace amounts of lead, cadmium or mercury. It really does not take much of any of these three elements to put them over the allowable limits to RoHS.

So, can I assume that the "other" is pure iron for 316 stainless?

 

[EdStainless]

The RoHS levels are very large compared to what you might find in SS that is made by a reputable supplier. In order to bet low carbon levels the molten metal has oxygen blown through it. Considering how easily these (Hg, Pb, Cd) metals oxidize it is assured that they are not even detectable in steels made by this method.

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Plymouth Tube

 

[TVP]

phili22,

Other than the lead (Pb) concentration, RoHS does not pertain to bulk metals like steel or stainless steel alloys. Cd, Hg, Cr⁶⁺, PBB, and PBDE only pertain to polymers, coatings or surface contamination, not the bulk metal.