Jerry,
The rocker arms as referenced in the TM appear to be forged, but I'm not 100% sure. However, since it is an Army TM, I'm thinking perhaps they were a little less worried about the cost of repair to the customer - hence the "discard" recommendation.
Your firearm example is well taken. I know that the heat treatment of many firearm receivers is a critical factor in their performance - with the idea that the outer surfaces are hard in order to to resist wear, while the inner core remains more ductile. This often extends beyond case hardening. If you're into old firearms, I'm sure you know the story of the "low number 1903 Springfield rifles", and the potential ramifications of improper heat treatment. For those who may not, during WWI, as production was ramping up, many were improperly heat treated - causing the receivers to be brittle and ultimately break into multiple pieces when fired. Obviously not good for either the rifle or the shooter.
That's kinda what led to my original question. If the base heat treat process (as opposed to case hardening) inherently left the surface harder than the core. If there was a surface hardening of some type applied. Or if the metallurgy was consistent all the way through the cross section of the tip. Base on everyone's experience, it sounds like its probably the latter.
As you also mentioned, stamped rockers like on the small block Chevy are extremely hard at the friction surfaces. I'm betting that the steel they use has to be fairly ductile in order to make it thru the stamping process, which dictates the application of a surface hardness treatment at the major wear points.
I'm probably over thinking this way too much. I think that I'll just shut up now, grab my belt sander, and go refinish some rocker arms...
Best Regards...
Bob
