Heavy Duty Wheels

[kgwhipp]

Hello Metal heads,

I'm working on a project that has some heavy duty wheels running against a track made from waterjetted plate. These won't ever seen a shock load but will potentially be run with a massive amount of weight on them, it may be as much as 25k-lb, but is more likely to only see around 16k lb in normal duty.

We usually use plain A36 for the track, but even if made very thick I don't believe the surface will last with the heavier loads here.
I'm assuming the failure mode will be the contact stress of the material causing eventual pitting. I think the pitting is more likely to happen on the plate steel.

Small quantity run of around 40 wheels. I'm trying to figure out the ideal material type and what processes to use.

I've sorted out to two options that I believe will be a good fit, for the wheels. I'm open to anything at this early stage.

Use 8620 steel.
Machine OD, ID stays undersized.
Optional: Mask off ID
Case harden, (Heat with carbon atmosphere intrusion and quench). I'm told this will result in .03-.04" of 60 HRC hardness on the outside and 35HRC core.
Finish machine: (If masked during case harden, machine with CNC lathe. If fully hardened, bring to ID with grinder)

Use 1045 steel.
Machine OD, ID can stay undersized or be machined to finished dimension.
Flame harden: Told it will yield .05-.06" of 53HRC on the surface. No idea what's going on inside.
Finish machine? (Prefer to not have to do another process)

The track, I have no idea at this point, but I believe the only material in 4'x8' sheets would be something like 1045 and even then, I'm a bit scared to find out how much more of a premium it will be over our usual A36.

Any thoughts/advice you folks can provide will be greatly appreciated! FYI: My WAG calculation for contact stress is 370ksi, but this comes down to 92ksi if I reduce the crown and load.




-Kevin

 

[arunmrao]

1045 steels induction or flame hardened are being popularly used for the application. 8620 was not considered due to cost considerations .

 

[kgwhipp]

I'm leaning towards 1045 because I can rely on having the same material for the wheels as the rail.

I wouldn't assume so, but is there a risk of the hardened shell flaking off if overloaded? Would a temper be needed after the quench?

Would induction hardening be preferable to flame? I'd assume induction would harden the bore making it harder to machine for the eventual bearings.


-Kevin

 

[arunmrao]

In my limited experience for over 10 years, there was no experience of the bore hardening or any flaking as long as the hardening process was sound. Hope this helps.