4140 Annealed parts. Need to decide on HT procedure.
4140 Annealed parts. Need to decide on HT procedure.
(OP)
We have some parts that look like stars, are made from a chuck 1.5x1.5x.75", have a hole in the middle as well as some small features machined into the top about .150" diam. We used to make these parts from 4140HT which is HRC28-32. We had problems pushing the parts around on the machines and the hardness, while it did work, should have been harder.
So we are remaking from annealed, and primarily just need about .030 case hardening to near max hardness but I know that would be difficult with these parts. I am curious what procedure might be preferred to achieve the highest surface hardness while still retaining some "chewy inside"?
Even if they will ultimately through harden due to the geometry and alloy grade, we need to decide how hard we can practically go without problems. From the charts, it looks like HRC50 is acheivable all day long. Would really like to see HRC60 but I understand the carbon issues or lack there of.
Also need a procedure that will be simple and cheap for our heat treat source. Need to be under a buck/part for this.
So we are remaking from annealed, and primarily just need about .030 case hardening to near max hardness but I know that would be difficult with these parts. I am curious what procedure might be preferred to achieve the highest surface hardness while still retaining some "chewy inside"?
Even if they will ultimately through harden due to the geometry and alloy grade, we need to decide how hard we can practically go without problems. From the charts, it looks like HRC50 is acheivable all day long. Would really like to see HRC60 but I understand the carbon issues or lack there of.
Also need a procedure that will be simple and cheap for our heat treat source. Need to be under a buck/part for this.





RE: 4140 Annealed parts. Need to decide on HT procedure.
RE: 4140 Annealed parts. Need to decide on HT procedure.
I think the temper was where I was getting confused. The higher 800F would pull back the hardness a bit but would at least resist any concerns of cracking. This part operates in a high vibration environment but otherwise shock loads and impacts are minimal.
RE: 4140 Annealed parts. Need to decide on HT procedure.
With the 4140, you can try to flame (or induction) harden the surfaces you need to have hard. The cost for this is going to be highly dependent on quantity, since you will have a high set-up cost. You should be able to get a 1/8" flame hardened layer to hold 50 HRC or so. If the annealed material is too soft to support the anticipated loads, you may need to Q&T the parts to 28/32 HRC before flame hardening.
rp
RE: 4140 Annealed parts. Need to decide on HT procedure.
RE: 4140 Annealed parts. Need to decide on HT procedure.
I thought carburizing was expensive anyway? Or IIRC, this involves a vacuum furnace and intro a high carbon gas like Methane? IE, about as easy as heat and quench?
RE: 4140 Annealed parts. Need to decide on HT procedure.