Chemical Composition of nickel alloy

  • #1
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Summary:
chemical composition
I ask the foundry to cast nickel alloys and I took a piece metal to do a chemical test.

The element composition of the nickel alloy is Ni 70% Cr 12% Fe 1.2% Mo 2.5%....so far they all are in the allowable range.
But I found the alloy also contains W 0.004% !

Is this the normal condition ? ?
I check the regulation of chemical composition , it only indicates that this alloy need contain Ni ..% Cr ..% Fe..%....but it doesn't say the limit of other impurity of element.

And may SS 316 contain a little bit other impurity element like W 0.03%, V 0.02% ?? Normal??
 

Answers and Replies

  • #2
.Scott
Homework Helper
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The spec sheet (Nickel 316) specifies that iron should make up the balance.
But the best precision is specified for Phosphorous (0.045%). This implies that all values, including "balance" are specified to no better than +/- 0.005%. So 0.004% total impurities would barely pass the "balance" specification. You could arguably reject such a sample.

I don't know what is "normal", but either W 0.03% or V 0.02% would be out of spec.
 
  • #3
Baluncore
Science Advisor
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Try to identify the source of the tungsten. If I remember correctly, Mo contaminates W ore, and is difficult to separate. So my first guess would be that it comes in with the molybdenum.

If the materials are derived from recycled HSS tooling, that would explain the mix of W, Mo and V.
 
  • #4
17
2
Try to identify the source of the tungsten. If I remember correctly, Mo contaminates W ore, and is difficult to separate. So my first guess would be that it comes in with the molybdenum.

If the materials are derived from recycled HSS tooling, that would explain the mix of W, Mo and V.

Is there any regulation about chemical composition about stainless steel which is made from recycling scraps ?
Like the percentage of impurity substance such as W , V and etc should not exceed the limit values.
 
  • #5
Baluncore
Science Advisor
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The composition of stainless steel will be specified in the National Standards.
For example; https://www.bssa.org.uk/topics.php?article=370
Follow that to; https://www.bssa.org.uk/topics.php?article=44
Permissible product analysis tolerances on the cast analysis ranges given in EN 10088-2
At the very bottom of that page is a table of limits for different elements, including vanadium.
Vanadium <0.20 ±0.03
So if V is specified as 0.00%, it can be up to 0.03%
That might suggest the alloy with V=0.2% was within spec.
 
  • #6
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My sample is a nickel-based alloy
The specification is A494/A494M Specification for Castings, Nickel and Nickel Alloy

I found this

http://209.195.157.233/EDIT/html_historical.cgi?A781/A781M+12a

It said that

5.3 Product Analysis—A product analysis may be made by the purchaser from material representing each heat, lot, or casting. The analysis shall be made on representative material. Samples for carbon analysis of carbon and alloy steel shall be taken no closer than ¼ in. [6 mm] to a cast surface, except that castings too thin for this shall be analyzed on representative material. The chemical composition thus determined shall meet the requirements specified in the applicable specification for the grade involved, or shall be subject to rejection by the purchaser, except that the chemical composition determined for carbon and low alloy steel castings may vary from the specified limits by the amounts shown in Table 1. The product analysis tolerances of Table 1 are not applicable as acceptance criteria for heat analysis by the casting manufacturer. When comparing product and heat analysis for other than carbon and low alloy steels, the reproducibility Data R2, in Test Methods E353 or E354, as applicable, shall be taken into consideration.

TABLE 1 Product Analysis Tolerances

Element​
Range, %A​
TolerancesB,C Over Maximum or Under Minimum Limit, %​
C​
up to 0.65
above 0.65​
0.03 × % CL + 0.02
0.04​
Mn​
up to 1
above 1​
0.08 × % MnL + 0.01
0.09​
Si​
up to 0.60
above 0.60​
0.22 × % SiL − 0.01
0.15​
P​
all​
0.13 × % PL + 0.005​
S​
all​
0.36 × % SL + 0.001​
Ni​
up to 2​
0.10 × % Ni L + 0.03​
above 2​
0.25​
Cr​
up to 2
above 2​
0.07 × % CrL + 0.04
0.18​
Mo​
up to 0.6
above 0.6​
0.04 × % MoL + 0.03
0.06​
V​
up to 0.25
above 0.25​
0.23 × % VL + 0.004
0.06​
W​
up to 0.10
above 0.10​
0.08 × % WL + 0.02
0.02​
Cu​
up to 0.15
above 0.15​
0.18 × % CuL + 0.02
0.05​
Al​
up to 0.10
above 0.10​
0.08 × % AlL + 0.02
0.03​

Is this tolerance only for carbon and low alloy steel castings?
Or this also can apply to the A494/A494M Nickel Alloy?
I want to know the nickel-based alloy (ASTM A494 series ) having W 0.004 inside is allowable or not.
 

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