Permissible chemical composition tolerance

[morris more]

Where could find the regulation about permissible chemical composition tolerance for nickel-based alloy ASTM A494 and stainless steel 316?

Because i ask a foundry to cast ASTM A494 nickel based alloy but the product has W 0.004% inside.

And SUS 316 product has Cu 0.3% inside.

Is it okay ??

 

[EdStainless]

First, 316 is not a Ni alloy it is an iron based stainless steel with Cr and Ni.
Second, what spec are you working to? You say A494 but you also mention SUS316, these are different.
And 316 is not covered by A494, only Ni based alloys are.
The stainless grades are covered on A743/A744.
As to a small amount of W in the alloy, this would be considered a trace. It was not deliberately added and it is not enough to change the grade designation or properties. They were not obliged to report it. You can ignore it.
Cu is another matter. I would not want 0.3% Cu in my SS, it makes welding very difficult and does not add anything.


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P.E. Metallurgy

 

Look in the section 'Reference Documents' found near the front of every ASTM material standard and you will see the master standard for that type of product. It contains all of the common requirements such as dimensions and tolerances.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[bobjustbob]

You find the chemical requirements in the specifications that you ordered the parts to. If you ordered the Ni based casting to ASTM A494, the standard chemical composition is listed there. This standard lists the applicable standards for chemical testing and such. As an unlisted element, unless it is deliberately added and does not make it a different material it does not need to be listed. If you wanted to specify the W content then that should have been included on the purchase order. As far as .004% W content, that is such a trace amount I am surprised that it was on the CMTR.

Was the 316 from the same foundry? If so it would be CF8M from ASTM A351 or A744. 0.30% Cu in a cast stainless is not unusual. I would not get excited until it got above 0.50%. Even at that point it is not rejectable, just time to adjust the recipe with less returns.

Bob

 

[morris more]

Two kinds of metal, ASTM A494 CY5SnBiM Nickel-base Alloy and sus 316, I ask the foundry to cast.
I did the chemical analysis and found ASTM A494 CY5SnBiM Nickel-base Alloy contains 0.004%W
and sus 316 contains 0.3%Cu.
Because it both will be used in food contact so a little bit worried if it is okay.

Why 0.004% W is in the alloy ? Because the raw material normally contains some trace elements which are allowable?

 

[bobjustbob]

The V was in the raw material. It is in as such a minor constituent that manufacturers of alloying elements do not go through the expense to remove it.

Bob

 

[EdStainless]

Many Ni alloys do contain W, so if they use some of them in the feed (to get Ni and Cr and/or Mo) they would get a little W. There is no way to remove it, all that you can do is dilute it to lower levels.
The same is true of Cu in SS. The 0.3% is not too unusual, but at that level is may have a negative impact on weldability. This is the especially true if you are welding a high Cu alloy to a low Cu one, though S has a stronger impact (you need a little, but too much is bad. people aim for 0.008-0.017%)
The military specs set limits at 0.25%Cu, but up to 0.50% is common in commercial grades.

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P.E. Metallurgy, consulting work welcomed

 

The V was in the raw material. It is in as such a minor constituent that manufacturers of alloying elements do not go through the expense to remove it.

Vanadium isn't just another alloy element, it is a powerful spice.

Since seeing stress relief cracking in a highly restrained weld in 8" thick plate a long time ago, I have suspected that steelmakers add V or Zr intentionally to help thick hot rolled sections pass mechanicals. I never was able to confirm it though.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

IM, the old trick isn't that you add it deliberately, you just use scrap that has a little bit.
This shows up in SS with Nitrogen. You aren't required to report it in non-"N" grades, but you can add as much as you want to non-"N" grades. While N raises strength at RT it does not improve high temp performance. This can lead to some poor decisions/outcomes.

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P.E. Metallurgy, consulting work welcomed

 

[mrfailure]

Far as I can tell, ASTM A494 does not call out any specifications for product tolerance of nickel-based alloys, so composition shown applies to both the heat and the product. SUS 316 is just a generic name that only applies to composition (as does equivalent Type 316 in the US that has composition defined under UNS S31600). You need to first find the Japanese JIS specification being used, then look through it to find the relevant product tolerance.