chemical composition alloy percentage tolerance
chemical composition alloy percentage tolerance
(OP)
Dear Friends,
I am working as a design engineer in Oil and Gas industry.
Generally in chemical property of steel or other material, Alloy percentage has been given only without Maximum and Minimum condition or sometimes , it has been given only with Maximum condition .
Do any have answer that why alloy percentage has been given with maximum condition? Mean what about Minimum condition also ???
or what standard , I should follow to see alloy percent tolerance......
Kamlesh
I am working as a design engineer in Oil and Gas industry.
Generally in chemical property of steel or other material, Alloy percentage has been given only without Maximum and Minimum condition or sometimes , it has been given only with Maximum condition .
Do any have answer that why alloy percentage has been given with maximum condition? Mean what about Minimum condition also ???
or what standard , I should follow to see alloy percent tolerance......
Kamlesh





RE: chemical composition alloy percentage tolerance
RE: chemical composition alloy percentage tolerance
RE: chemical composition alloy percentage tolerance
Perhaps he refers to S and P contents, which have a max specified(0.05%Max) or as the case maybe.
"Even,if you are a minority of one, truth is the truth."
Mahatma Gandhi.
RE: chemical composition alloy percentage tolerance
For example , I have attached the ASTM A105 chemical composition here.
Like Maximum condition of S, Co, Ni, C, ....
what about minimum condition ??
I have seen same condition in other standard also.
Kamlesh
RE: chemical composition alloy percentage tolerance
RE: chemical composition alloy percentage tolerance
For example on "L" (low carbon) grades of stainless there is no min for C, you want as little as possible.
There is another issue here, with all alloys. When you analyze a finished product you are allowed a tolerance outside the original specification range. These amounts vary but each specification system has a method for allowing these.
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P.E. Metallurgy, Plymouth Tube
RE: chemical composition alloy percentage tolerance
Thx a lot . I have been understood now.
Just for my clarity, I have attached the UNS N0 6625 material chemical composition .
Aa Per my understanding, for maximum condition alloy, we can add minimum value of alloy based on our experience and their effect on material behaviour. Right??? There is no international standard or some thumb rule right?......
Kamlesh
RE: chemical composition alloy percentage tolerance
"Aa Per my understanding, for maximum condition alloy, we can add minimum value of alloy based on our experience and their effect on material behaviour. Right??? There is no international standard or some thumb rule right?......"
Why do you need to do it. Just specify the standard and leave it to the vendor to supply conforming to standards. If you attempt providing our own interpretation, in the event of a dispute, you will have little protection.
"Even,if you are a minority of one, truth is the truth."
Mahatma Gandhi.
RE: chemical composition alloy percentage tolerance
1. Each mill balances the chemistry slightly differently, their targets as mil specific.
2. Mo being the most expensive element added will tend toward the low side of the range.
3. There will be certain patterns that everyone follows (elements to the low side or high side).
Some companies have their own specs, but in order for them to be usable they have to fall in the 'Goldilocks' zone, they have to be more restrictive than the UNS (or ASTM) and they still must allow what almost everyone is actually making.
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P.E. Metallurgy, Plymouth Tube
RE: chemical composition alloy percentage tolerance
Material specifications may have an allowable tolerances for delivered product that goes beyond the specification requirements. In order to know whether such tolerances apply, you have to first make sure you have the complete standard.
In your example of ASTM A105, the general requirements of the specification state "Product furnished to this specification shall conform to the requirements of Specification A961/A961M, including any supplementary requirements that are indicated in the purchase order." The allowable tolerance of the finished product for specified elements is defined in ASTM A961/A961M.
Your other example involved UNS N06625 (IN 625). UNS is strictly a specified composition range, and no product tolerance can be applied if that is the only specified requirement.
RE: chemical composition alloy percentage tolerance
It's not especially uncommon (in refining at least) to specify 316 with min 2.5% Moly for example, when the spec is 2-3%.
RE: chemical composition alloy percentage tolerance
Thanks a lot for giving so great information.
Kamlesh