piston ring material spec question

[ivymike]

Hello all

I've got a material spec in front of me, for a pearlitic gray cast iron piston ring. The young's modulus is 90-120 GPa, and the material spec is MF 227. I'm guessing that's a Mahle in-house spec, and I was wondering if anyone knows a rough equivalent ASTM/SAE/other spec that I could look up online.

Thanks,
Isaac

(the closest I've found so far in terms of E and hardness is "Standard gray iron test bars, as cast, ASTM class 30" but I don't know if that material matches in other properties)

 

[TVP]

I would agree that this is probably an internal spec at Mahle. The following ASTM specs may be useful to you:

ASTM A 159 Standard Specification for Automotive Gray Iron Castings

Grades G3000, G3500, and G4000 are all pearlitic grades, with G4000 being the hardest-- 217-269 HB.

ASTM A 48/A 48M Standard Specification for Gray Iron Castings

Class 30 has a modulus range of 90-113 GPa. Class 35 has a range of 100-119 GPa.

The following SAE spec may also be useful:

SAE J431 Automotive Gray Iron Castings

It discusses many of the applications for the various grades, although I did not see anything about piston rings.

 

[EngJW]

I don't think there is an SAE standard for piston ring materials. Gray cast iron is the basic material. Ductile iron is used for the top ring in high performance applications. They are probably proprietary modifications of the standard SAE materials to provide for the unique requirements of piston rings as compared to more traditional castings.

John Woodward