Using 4140

[DPittman]

So now that I secured a lifetime supply of 4140 I am wondering about using it to its potential.

Is it necessary to heat treat the annealed product in order to get any different qualities out of it then just any other old mild steel?

I know that if it is properly hardened and then tempered that is a whole different story.

I recently made some steering component pins for an old tractor out of some unhardened 4140 on the advice of my brother who said in his experience, hardening was not necessary.

Alexander, you said you use a lot of 4140 at work, I imagine all that goes through a heat treatment process? What are your thoughts?

Anyone else have an opinion or suggestion they would like to share?

Don

 

[Dabbler]

4140 is pretty easy to heat treat and anneal. When you do, you can get 120K psi out of it instead of 50K in the annealed state. There are good heat treat suggestions all over the internet. If you don't cut it with the best SFPM or with the right tools, it can 'gall' giving a bad finish. It pretty easy to clean up with a file and emery, though.

 

[Dogpounder]

Hi Don

Did you get any of the 6.75 o.d. x 2" o.d. x 30.75" L pc's I'm looking for one to buy

 

[DPittman]

Hi Don

Did you get any of the 6.75 o.d. x 2" o.d. x 30.75" L pc's I'm looking for one to buy

I haven't actually picked mine up yet as Josh has been kind enough to store the material for me. I don't know exactly what I have. I'll let you know if I've got something I can get rid of.

Don

 

[Dogpounder]

Thanks very much Don

 

[Alexander]

Alexander, you said you use a lot of 4140 at work, I imagine all that goes through a heat treatment process? What are your thoughts?

4140 is still a great material before you harden it. We dont harden all our parts but hardening will help prevent wear and dents on your finish product. The main downside to hardnening it is it will warp after heat treat. For example i made some 4140 v-blocks for my self. rough mill the blocks then surface ground all sides leaving .003" on all dimentions. After heat treating I finish ground them to size and noted about .002" warp in the small blocks. If you have a big part with threads on the od or id you may run into problems so keep that in mind.