"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.

Harold