I posted this elsewhere but here it is again:
Specs for new rail:
Standard rail steel:
.74 to.86% Carbon,
.75 to 1.25% Manganese,
.10 to .60% Silicon
Minimum Brinell (of unhardened surface) 310 or 370 dependant of grade ordered.
Low Alloy Rail Steel
.72 to .82% Carbon,
.80 to 1.10% Manganese,
.25 to .40& Chromium,
.10 to .50% Silicon
Minimum Brinell (of unhardened surface) 310, 325, or 370 dependant of grade ordered.
The head may or not be hardened depending on the piece of track you have. Hardened head rail is used in heavy curve applications, or so I am told.