440C, AMS 5880 vs. AMS 5630J, what is the difference?

[bulldogwld]

I have a manufacturing order using 440C that is stopped. The requirement is 440C per AMS 5880 and the material cert on steel we received says AMS 5630J condition A. Can you please tell me the difference between them? Chemistry? Physicals?

 

[TVP]

I don't have the specs immediately available, but the differences are small, unless this is a bearing application. AMS 5880 is for bearing quality material, while 5630 is a more general grade. The chemical composition for alloying elements like Cr, Mo, etc. are the same. The specs differ in how the steel is refined, and what the P, S, and O contents are allowed to be, which influences how many non-metallic inclusions there are. Excessive non-metallic inclusions degrade the surface finish, which means the steel can't be polished as well. This can lead to flaking and spalling under high contact stresses. They also reduce the corrosion resistance by promoting pitting. So if this is for a lightly loaded roller or valve, etc., then probably no meaningful performance difference. Don't even consider it if this is a highly loaded bearing.

 

[armourian78]

We use 440C per AMS 5618 (VAR), AMS 5880 (airmelt), and in the past have used AMS 5630 (airmelt) for bearing applications.
The alloy composition of AMS 5880 vs AMS 5630 is almost identical: Only the Copper limit of is different - AMS 5880 0.75Cu, AMS 5630 0.5Cu. However depending on which revision of AMS 5630 is specified, depends whether certain NDT and cleanliness requirements have been performed, for example AMS 5630 rev K has ASTM E45 micro-inclusion cleanliness and AMS 2303 MPI testing requirements, whereas AMS 5630 rev L has neither requirements.

If ASTM E45 and AMS 2303 are included in your AMS 5630 rev J to the same level, I would say the differences are negligible.