STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
(OP)
Here is the deal. We had pretty much settled on 8620 and then carburize it. Then we found out that 8620 is pretty much non-existent in flats. So now we are back to the drawing board... The part needs to be through hardened to around HRC 35 depending on alloy. The fork tips need to achieve around HRC60-65. I have looked again at 4340 and induction harden the fork tips but not sure how hard I can get with 4340 and also how it might work to try and surface harden a cross section of only .200". I am concerned that is the whole thing goes to HRC60, we would have a reduced fatigue life.
I do not want to get into nitriding and trying tokeep the process in house. We were going to pack carburize the parts until we learned we cannot get 8620.
So I guess we are either looking for a good structural material that will work with carburizing, or an induction hardenable alloy with similar properties. Both commonly available in flats or rectangle bar, not cut from plate.
I do not want to get into nitriding and trying tokeep the process in house. We were going to pack carburize the parts until we learned we cannot get 8620.
So I guess we are either looking for a good structural material that will work with carburizing, or an induction hardenable alloy with similar properties. Both commonly available in flats or rectangle bar, not cut from plate.





RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
For wear resistance on thin parts, you may want to consider ferritic nitrocarburizing. Use a simple 1XXX or 51XX or 41XX or 43XX steel that meets your strength needs and then put it in the pit/furnace for the surface treatment.
RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
Again, we are looking to keep all processes in house. We have an oven and willing to setup for induction heating but some of the case harden methods are too dangerous for us to mess with. We planned to use pack carburization if we were to use 8620. Very open to ideas on this one. 300K psi ultimate, HRC59+ surface....
RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
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RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
If we cannot get 8620, we were looking at pack carburizing something like a 4320 or maybe 4340. We planned to slow cool so as not to harden the part at that stage. Then follow up with a harden process and temper..
Any thoughts on pack carb on 4000 class alloys?
RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
If you can discuss with any heat treater in your area,he can provie a boquet of solutions. But, I gues you want to stay fixed with pack carburizing.!
Learn the rules,so you know how to break them properly.
Dalai Lama
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RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
If we could find something that would induction harden to our specs, that could work too. No one locally does nitriding. We were pretty fixed on just using 8620 and taking them in to be carburized but the lack of material selection is killing this project. Cutting from rounds simply is not cost effective.
RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
You can get it in variety of bar and flat shapes as well as casting to near net shape.
Since your gears are already hardened steel the dissimular metals concept is in your best interest also. Works real well in engine cyclinders.
RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
RE: STILL TRYING TO SELECT MATERIAL FOR TRANS. SHIFT FORK
Your shift fork is basically a semi-circular finished shape. I'd suggest trying this:
Call a local forging house and see about rolling a ring segment shape from 8620 rectangular bar. There should be no tooling costs, it will minimize material scrap, you'll get a fairly close net shape, and you'll get forged properties to boot.
I think you'll be surprised how inexpensive those rolled rings might be. The lower ram material cost also might be enough to offset the rolling charges.
Good luck.
Terry