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Steel Composition

Steel Composition

Steel Composition

I have a chemical analysis and have searched several sources including matweb but I don't know any max or min values and it gives a very broad result of 1700 possibilities, no help.
I would like to cross this to a UNS or AISI number if possible.  Is there a better calculator or can someone help?

C  0.18
cr 1.14
mn 0.96
ni 0.48
si 0.31
s  0.032
cu 0.03
p  0.017
mo 0.01
fe balance


RE: Steel Composition

A quick look through SAE J404 Chemical Compositions of SAE Alloy Steels does not show any matches.  Can you provide a few more details?

1. What analytical method was was used to determine the composition?  Was the sample sectioned from a discrete part?

2. Do you know if the product form is sheet or bulk (rod/wire/forging)?

3. What is the country of origin for this steel?

RE: Steel Composition

The part was cross sectioned from a forging and sent to a metallurgy firm for analysis. The part is a drive pinion from a recreational vehicle. The vehicle is built in the US but it is a possibility that the component was made in Japan.      

RE: Steel Composition


Thanks for the additional information.  Unfortunately, this still does not fit into any standard steel grade with which I am familiar.  The problem is the Ni content.  There are some case hardening steel grades that could be a good fit based on the C, Mn, Cr, and Si levels, but the Ni and Mo levels don't fit.  Most of the standard case hardening steel grades used in North America, Europe, and Japan are alloyed with either Cr-Mn, Cr-Mn-Mo, or Cr-Mn-Mo-Ni.  There are no Cr-Mn-Ni grades.  Typical steels used for hypoid drive pinions include 8620 and 4320, with the following magazine article serving as a good reference on the subject:


If I were you, I would confirm with the lab that there is not a typo, etc. for any of the listed concentrations, specifically the Ni and Mo.  I would also discuss with them the possibility that the Ni concentration is erroneous, possibly due to something not being calibrated or due to contamination (electroless nickel plating? Ni-modified phosphate surface layer?).  Otherwise, just ignore the specifics of the composition, and choose a standard North American grade that can achieve the necessary performance characteristics (surface hardness, core hardness, heat treat processability, machinability, etc.).

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