Composition of 4330 vs. 4330mod vs 4330V and difference between AMS#s

[mooseheadm5]

Greetings,
I have been tasked with ordering some "4330" for a coating project our company is working on to restock what had been previously ordered. So far I have figured out that what the contract called for was 4330V, but what someone purchased before was listed as 4330MOD (CEVM, N&T.) I have attached a file listing the composition.
I did a bunch of searching of google and this site and learned what some of the information was. I have the Aerospace Structural Handbook open to the 4330V section (May1992 revision)open on the desk next to me.
It looks as though this fits the specs for 4330Vmod (AMS6411 and AMS6427) not just 4330mod because of the vanadium content.
Now the questions:

Did we get the right stuff to begin with? It seems like it. They list is as conforming to spec AMS6411F and 6427J (as well as all the other numbering systems it fits.) The older Aerospace Materials book has the older 6411D and 6427G compositional specs listed. From the SAE I gather that the current specs are 6411G and 6427K. It also seems from the links below that the 6411G spec has tighter controls on carbon content than 6427K (which differs from what I am seeing with the specs listed in the Aerospace Structural Materials Handbook.)

http://standards.sae.org/ams6411g/

http://standards.sae.org/ams6427k/

Have any of the other compositional specs changed?

Does anyone know why what we bought is listed as 4330MOD and not 4330V or Vmod?

Is the only difference between the AMS6411 and AMS6427 an allowance of higher phosphorus and sulfur content? If not, what are the differences? The UVA Engineering library (where I sit as I type this) does not have the AMS specs separately.

Thank you in advance for the assistance. I think I have close to everything I need to know, but I'd really like confirmation from someone that knows because we definitely don't want to go back and redo the coatings unnecessarily or send of coatings on the wrong substrates.

 

[redpicker]

The notations 4330, 4330Mod, 4330V, and 4330VMod are all just a rerference. As far as I know, there is no AISI 4330 chemistry range, but individual steel producers have developed their own chemistries to meet the various specifications.

When a "M" or "Mod" is added to a steel grade, it only signifies that they chemistry has been modified from the customary ranges. If a "V" or "V Mod" is added, this generally indicates that the vanadium content is part of this modification. Other than indicating that the chemistry has been modified, there is really nothing more that the designation implies. That is, the modification could be keeping the S & P below 0.010, for example. Or, it could be a restricted carbon range. What is important is does the steel meet the applicable AMS (or other referenced) specifcaiton.

rp

 

[redpicker]

Just to add....

I noticed the MTR you posted listed the yeild as 202 KSI and the UTS as 239 KSI, with a hardness of 227 BHN. That's a neat trick if you can do it. Something does not seem right with that to me. Is there something I am not understanding about the reported properties?

 

[salmon2]

Good one, redpicker

 

[mooseheadm5]

Thanks for the help. Between this and the I have what I need to go ahead and order the material. If the PI on the project had given me enough info to begin with, I wouldn't have had to bother you guys, but such is life.
Thanks again!