1018 or 4140?

[Rhodan]

I'm wondering in the McMaster Carr "precision acme rod" in black oxide coated 4140 steel gives any advantages over 1018? I know 4140 is harder but is the finish any smoother? (more power for cutting and less for turning the AB nut). Is 4140 less inclined to whip or anything?

Inquiring minds want to know Thanks!

[Glacern]

4140 has higher tensile strength, but offers no advantages in terms of rigidity. Both metals have the same modulus of elasticity.

I don't know if Mcmaster's 4140 acmes are smoother.

[mc-motorsports]

4140 will have better wear charictaristics as it is in the Chome-Moly family of steels, 41xx. Also has better tensile streangh and is hardenable, all advantages over 10xx steels, for your application.

MC

[handlewanker]

Yeah, 4140 is as hard as a whores heart to machine, but for hi tensile applications it's the bees knees.

You'll still be running it against bronze nuts, so no advantage wear wise.

To get a good finish it needs to be ground.
Ian.

[Boots]

There is a good reason why 4140 makes a good gun metal. It's tuff stuff.....