On Sun, 02 Aug 2009 01:27:30 GMT, "Harold and Susan Vordos"
wrote:


"Jordan" wrote in message
...
I made a rear axle for my rigid-framed motorcycle out of 4140 steel, and
the thing bent in use. I was advised that heat-treatment was optional, but
not really necessary, so I didn't do that. Was this advice wrong?
The axle diameter is 9/16", and bike weight = 375 lbs. I do sometimes hit
the odd pothole, but nothing major.

Jordan

You would have been wise to choose 4140 HT, which is pre-heat treated to
roughly 32 Rc. It is still very machinable, and much stronger than annealed
material.

Yield for annealed material is about 60,000 psi, not much better than
low carbon cold rolled. Pre-hard (HT) is about 125,000 psi. Yield can
go as high as 250,000 with a 400F temper.

--
Ned Simmons