Hardness of materials- rail and wheels

Some engineering friends were asking me which material was harder- rails or wheels. I didn't have a good answer. I assumed rails were harder since I figured rails would wear out before rails. Can anyone guide me to the right answer? Also, they were asking me about the hardness of steel on some sort of scale. Anyone got any idea?

-otto-

I've seen some data somewhere, I'll poke around a bit. They are very close, as an observation. Slipping wheels cause the rails to melt, or "burn". Sliding wheels cause the wheels to melt, or burn. They should be very close, on a scale hardness, or excessive wear would result. I'll look in my track stuff, and see what pops up.

here , the rail head is hardened , whereas the wheel is just machined steel . I think the wheel cannot be too hard otherwise it would be suspectible to cracking . they apply the wheel tread to the wheel inner by heating it , dropping it on , then letting it cool . which would negate any hardening unless the wheel was then cooled rapidly .

We don't put tires on the wheels, here in the States. (unless you have a steam engine or some oddball type of equipment) We have forged steel wheels, that are heat treated, and the entire wheel is pressed onto an axle assembly, without heat applied. If the wheel becomes damaged through pitting, chipping or gouging, it could be welded for a repair, but it then becomes a restricted item, and once a wheel is welded, it is "a welded wheel for life". We just change out the entire wheel and axle assembly here, and someone else gets to replace the wheels onto re-useable axles. Hard to imagine replacing tires on modern locomotives. As a general rule, rails here are also heat treated, in the vicinity of the rail ends, where the joints are, for structural strength due to vertical impact loading.

Hardness is based on scales like the Rockwell hardness Test, there are others but this page sums it up.
http://en.wikipedia.org/wiki/Rockwell_scale

It is a lot of material science, but
Steel that is hardened, is more brittle and bends less. To harden, you heat and cool slowly, and heat and cool slowly, etc

Being that wheels are machined, they are probably not hardened, and I would think that as flexible as rail is, it is not hardened very much.

So probably the hardness of both wheels and rail is very similar.

ok possibly they dont change tires here anymore either . thees been such a downsizing of the fleet theyve had enough weheelsets to no have to do anything for awhile .
its been 20 years since i was at egnieering school , but dont you have to cool quickly to harden steel ?

ts been 20 years since i was at egnieering school , but dont you have to cool quickly to harden steel ?

Yea my bad, It has been about that long for me too. What I remember is heating and cooling the metal in an oil bath. Then testing it on a Brinell Hardness machine.
Shows how much I remember. I think that is about how much calculus I remember also.

I read somewhere that the Belt Railway of Chicago used tires on some of their diesels. This was because of the extreme wheel wear, on account of all of the amount of irregularities in their track (banking over the above number of frogs, etc.