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ASTM Steel Chemical Composition Standards

ASTM Steel Chemical Composition Standards

ASTM Steel Chemical Composition Standards


I am a relatively new engineer so I apologize in advance if I am asking an obvious question. I've been tasked with an interesting, but slightly out of my field problem that has to do with the chemical composition of steel.

I am trying to compare test samples of steel components against ASTM specification standards. Basically it is QA work to make sure that the samples' chemical compositions comply with the ASTM standards. However I running into a bit of an issue with regards to what elements the ASTM standard includes in its "chemical requirements".

For instance in ASTM 705/705M, "Age-Hardening Stainless Steel Forgings", the "Chemical Requirements" table includes max % (by mass) values for Si, Ca, Ni, Al, etc. but omits other elements such as Fe, O, Co (elements that you would certainly expect to see in steel).

I suspect there maybe some sort of "baseline" values for these elements included in a "General Steel" Standard, but I cannot seem to find it. I understand the max percentages won't necessarily "add up" since they are all maximums values. However I find it strange that iron isn't included.

Is there anyone more familiar with steel/steel standards that can explain how these standards should be used?

RE: ASTM Steel Chemical Composition Standards

First, review A 751 as referenced in the material specification.
Stainless steel, along with steel and similar alloys are considered ferrous-based, which means they are iron based.

The chemical requirements referenced in the table in the material specification provide the necessary alloying elements by the supplier to achieve the stated mechanical properties. This is not identified as a chemical analysis, and is not intended to be one. This is why they are listed as requirements.

So, when you receive a test report which could have a ladle or heat analysis of the product, this is the complete chemical analysis and should be checked aginst the material specification requirements to have all of the required elements listed in the table and within their specified ranges.

RE: ASTM Steel Chemical Composition Standards

Only elements listed in the specification are required for certification. And the resolution in the spec is what you should report (not more decimal places). You need to also look up what the product analysis tolerance is, there is a range outside of the spec allowed for a final product analysis.
The only rules limiting other elements are ether just based on 'good workmanship' or the fact that you cannot deliberately add an element without reporting it (this is overlooked for very minor things like deoxidation additions). You also can't add something that makes the alloy into another grade. You can make it meet multiple specifications but it shouldn't meet multiple alloys within one spec.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

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