stainless steel identification

[klindsey]

Hello,

I have an analysis of the following metal whose source I am trying to identify

17.3 Cr
1.5 Mn
0.47 Ni
0.43 Si
0.11 Al ? (is this real or contamination)

0.0 Mo

it doesnt quite fit with any of the grades that I can check against.

Also is there a single listing of all AISI grade chemical compositions

thanks

Kevin

 

There are several grades of Stainless Which the above chemistry would fit, Most likely Ferritic Type 439, UNS-s43035, That is a proper amount of aluminium for that type of SS.

I use the Guide to Engineered Materials published every December by Advanced Materials & Processes.

Nick

 

[PAN]

Carbon content should be considered too. This might be ferritic or martensitic stainless steel.

 

[mcguire]

YES! Find the carbon and nitrogen content. This level of manganese and nickel would seem to indicate a martensitic grade since these are usually much lower in a ferritic grade.
Certainly analyze for niobium and titanium because the presence of these would indicate an attempt to make a stabilized ferritic.
The aluminum would seem to indicate a ferritc grade if you are sure if it's really there. I ahve never had an independent lab ( i.e. not from a producing mill ) that had its standards calibrated well enough to give accurate chemical analyses.

 

This is actually a response to mcguire.

I'm really suprised you've never had a lab that could properly do a chem analysis, I'm not certain bout SS, but the A2LA lab I used to work for is easily able to produce results on low alloy steels with a variation of no more than +or- .0089%wt Al (two sigma). I'm not sure if the additional high count channel for Cr would interfere with the results for Al but I dont think so since the atomic #'s are quite different. If you'd like I can send you results of daily check standard analysis on our Arc/Spark and the comparison to the certified standards.

Nick
njenrigh@hotmail.com

 

This is actually a response to mcguire.

I'm really suprised you've never had a lab that could properly do a chem analysis, I'm not certain bout SS, but the A2LA lab I used to work for is easily able to produce results on low alloy steels with a variation of no more than +or- .0089%wt Al (two sigma). I'm not sure if the additional high count channel for Cr would interfere with the results for Al but I dont think so since the atomic #'s are quite different. If you'd like I can send you results of daily check standard analysis on our Arc/Spark and the comparison to the certified standards.

Nick
njenrigh@hotmail.com

 

[mcguire]

Most labs don't have standards for the alloy ranges of stainless. Carbon and alloy steel standards are too far off. I have seen MANY really far off analyses from commercial labs.

 

So you are saying that the certified standards that the lab uses are not the composition on the certificate? Seems funny then that there would be any point in even doing a chemical analysis at all.

nick

 

[mcguire]

It may be a case of the lab's not knowing the grade being analyzed and so aren't properly set up for what's in there.
Take the above instance. If the grade were 439, the titanium range would probably be 0.25% to 0.45%. If it were dual stabilized 439, there would be a need to accurately measure niobium in the same range. How does the lab know what it should be looking for and in what amount.
The reading of 0.0% moly is suspect because it's almost impossible to get pure enough raw materials to get moly below 0.04%. Most likely it is an inaccurate reading.
Even stablized grades like 439 which use aluminum deoxidation average less than 0.035% Al. This reading is strangely high. Deliberate addition or inaccurate reading?
Ferritics always have Manganese less than 1.25%. The 1.5% seems erroneously high.
The analysis just doesn't add up, and this is what often occurs.

 

[Nick6349]

1. So you're saying that Arc/Spark (Optical Emission) 16 simultaneous element analysis is not adaquate? It seems to me that if a Lab is doing proper work with this kind of device they would not be looking for any element in particular just the actual composition of the burnt area.

2. My GEM shows composition of 439SS as:

C:.12 Mn:1.0 Si:1.0 Cr:17.0-19.0 Ni:.50 P:.04 S:.03 Al:.15
Ti:12*%Cmin-1.10

You are right the chemistry given fits no SS perfectly.

I rarely see Mo amounts in excess of .005% in low alloy steels, seems that the purity of raw materials is not an issue with these steels.

Thanks for the dialog.

Nick

 

[mcguire]

Your information is correct. The limits for 439 are seldom tested in practice. It is impossible to have 0.03% sulfur in 439 becuse the titanium removes it in refining in the AOD. If you put 0.5% Ni in 439 it may have brittle welds. All the effort in 439 is in reducing C and N as low as possible to minimize TiN levels which cause harmful inclusion defects.
Carbon steels can have low residuals because so much is made via blast furnace with very low metallic contamination. All stainless steel is made from a high proportion of scrap stainless and grades are commonly not well separated, so lot's of moly and nickel get into grades which really don't want to have them.

 

[Nick6349]

Ahh I see said the dim sighted young man....

so its actually the material, not the analysis method...

Nick