? on heat treating 1045

[A.K. Boomer]

building a planetary gear system and would like to make the gears as durable as possible,

iv done this before with identical material for gears and left the internal gear soft with no problems as there's so much surface area there where the planets connect,

but I heated and quenched the smaller planets and sun gear and had ok results, was just wondering if I should leave this one up to the professionals as this is a smaller more refined unit and need to have it right, is it something best suited for an oven and long period of heating? if so and there's no chance of warpage I would also have them do the larger internal/ring gear... know a place I can take them too if it takes an oven, will they just heat and quench or is it prolonged heating?

any sound advice is appreciated...

[Zahnrad Kopf]

There is simply not enough information there to answer correctly. What kind of loads will the train see? Input? Output? What kind of duty? What kind of duty cycle? Will it be unidirectional, or bidirectional? And lastly, what kind of process ( and control ) does your local place have and guarantee?

[A.K. Boomer]

Just want to make them hard not going to be shipping them off to NASA...

just hillbilly hard, and my main concern is warpage as they are already cut gears but in an annealed state and kinda "gummy"

was wondering if someone has experience with the carbon power in the tins and using less heat to get a case hardening on them instead of having to quench at around 1600 degree's F

just got off the horn with the heat treat guy and he said with his equipment it has to be quenched and gave him the dimensions of the larger ring gear and he stated that it most likely would squirm some,,, I don't want that if I can help it,,,

anyone ever heat 1045 in the high carbon powder to get results? would be a lesser heat and would not have to quench im assuming ------------- ? might be the ticket ----------- ?

[MattiJ]

Umm, whats the point of adding extra carbon? You still have to quench it if want hard surface.
AFAIK something like carbonitriding would allow slightly lower temps and milder cooling rates..
Or boriding as it doesn't need quench.

[Erich]

The carbon content determines how hard a steel can get. 1045 is medium carbon it won't get as hard as 1080 or 1095.

For any steel to harden it must cool rapidly. Plain carbon steels must cool most rapidly of all. If you don't cool quickly they don't get hard at all.

Adding expensive alloying ingredients like chrome, nickel, cobalt allow the steel to cool at a slower rate and still get hard.

The air hardening tool steels have so much stuff added they can cool by sitting on a bench after heating.

This is just the barest tip of the iceberg. Not even a 30,000 foot view of the subject.

I would buy pre hardened 4140 and cut my gears and be done. It is about Rockwell C 35

Another choice would be 17- 4 PH stainless. This can be hardened just by a 1 hour stay in a 900F or so oven. Not hot enough to scale and get nasty.

Otherwise, use 1045 and let distort. If you leave enough backlash in the design, the gear will run, they will just be noisier than more accurate gears.

[Zahnrad Kopf]

I would buy pre hardened 4140 and cut my gears and be done. It is about Rockwell C 35

Two points.

1. OP has stated that the gears are already cut. So starting over isn't really what they've in mind, as I understand it.

2. For the two or three weeks that I've been doing this, I have NEVER, ... EVER seen 4140PH actually come in at 35HRC. In my experience, that is a pipe dream borne of reading descriptions and not checking with reality. 4140PH almost universally arrives in 25/26HRC condition. So commonly, that it is a standing joke among people that use it regularly.

If one actually requires 4140 to be 35HRC, then they are best served to either purchase HT&T to spec, or do it themselves.

[J Tiers]

IIRC there are some 8000 series (?) steels that are extremely wear resistant. Have been often used for gears. Might be a bear to machine, and you have the parts , so....

The treating compounds case harden, Might be OK, might not. You probably want the gears hard enough not to wear, but still tough, so actually a case might be just what you want, if it does not end up spalling off. Would give a hard surface, with a tougher interior, even if straight quench hardened.

An oil hardening might be less likely to "squirm", and you also might harden the ring gear while clamped between plates, which I understand can actually do quite a bit of good. Teeth would still get hard, interior not so much as if just dropped in

[madman]

Hi . I make lots of small Jigs and crimp dies from 1045 (primarily thats all we have in stockQ!) I have actually heat treated it to a red colour and just toss it to cool or quench in a 5 gallon pail half full heat trat Oil. It actually came to about 54 Rockwell C a few times, . Hope this helps I do wish to ad it seems a bit brittle, we hit parts on it with arbour presses so lots of shock,

[A.K. Boomer]

Thanks all for all the varied info, I might just do them myself again and hope for the best - maybe get some heat crayons

they want $110.00 to do a minimum order like this so might just try it myself as that's almost as much as I paid for all the gears....


I used regular used motor oil to quench the last time is that a no-no?

wonder if Mapp gas on my propane torch would be enough heat - I do have a killer torch head for propane.

[Illinoyance]

OP doesn't say how he intends to deal with scaling. To prevent it a controlled atmosphere furnace or stainless steel wrap will be necessary. To assure uniform hardening it is necessary to hold the parts at temperature until the internal temperature stabilizes. That is usually expressed as minutes per inch of thickness soak time.

Machinery's handbook contains a wealth of information on heat treating.

[bob_s]

Thanks all for all the varied info, I might just do them myself again and hope for the best - maybe get some heat crayons

they want $110.00 to do a minimum order like this so might just try it myself as that's almost as much as I paid for all the gears....


I used regular used motor oil to quench the last time is that a no-no?

wonder if Mapp gas on my propane torch would be enough heat - I do have a killer torch head for propane.

The size of the gears, in terms of their mass, will govern how fast they cools when you dump them in the quenching tank.
Myself, I'd opt for quenching in salt brine cooled in the freezer over quenching in oil, because I'd know that they would be hardened as much as possible.
For small stuff I use one of those swirl style propane brazing torches.
Largest size would be equivalent of retaining nut from output shaft of suzuki SV-650 motocycle.
Bigger than that will require better heat containment of small forge or furnace or an old fashion charcoal barbecue.

[cijuanni]

2. For the two or three weeks that I've been doing this, I have NEVER, ... EVER seen 4140PH actually come in at 35HRC. In my experience, that is a pipe dream borne of reading descriptions and not checking with reality. 4140PH almost universally arrives in 25/26HRC condition. So commonly, that it is a standing joke among people that use it regularly.

Around these parts it is listed as 28-32 and almost is never harder than 28.

[J Tiers]

.....
Myself, I'd opt for quenching in salt brine cooled in the freezer over quenching in oil, because I'd know that they would be hardened as much as possible.
....

You may not WANT them as hard as possible, if that makes them too brittle, and too deeply hardened. Gears want a hard surface that does not wear badly, but a tough core so the teeth do not get stripped off by shock.

Rivett 608 lathes had cast iron (quite brittle) back gears, and it is very common to find that there are stripped teeth. Mine had all the teeth stripped from a pinion, and many from the other gears. Probably even 1018 might have lasted better. 4140 PH would be great.

[danlb]

If you have already made the gears, this may be of less help.

I found a nice writeup on 1045 in http://www.interlloy.com.au/our-prod...bon-steel-bar/

It has good procedures for many aspects of heat treating, including the annealing, stress relieving, quench, etc.

Since it's a medium carbon alloy, you should not need to use as hardening compound such as Cherry Red. That document says you should be able to case harden with a flame to RC56.

Dan

[wombat2go]

The issue with a one off prototype will probably be quenching the 1045.

Gears are more difficult to quench than shafts, plates, hubs etc.

The quenchant has to be turbulent right into the roots with no steam or air bubbles.
And impingement perfectly even for all teeth of the spinning gear.
The quench rings and tooling and pump/valves for spin quenched gear hardening
are dedicated to the part and fairly tricky, more by art and experience than science.

The other problems with in-furnace whole body heating is that the body heat in the through heated gear
surrounding the root, tends to impede the transformation of the root.
Unless heated in a reducing environment, scale will inhibit the quench and probably cause distortion.

The purpose of gear hardening is to extend fatigue life. On the contact area at sides of tooth flank
the case of martensite resists spalling.
At the root, the case of martensite is in compression ( by the underlying untransformed 1045)
and so the resistance to bending fatigue is increased.

With single shot induction gear hardening, dual or variable freqencies are often used,
along with high power density so that the carbon is in solution only in the required depth
and with cold backing steel, before quench. Even so, "the detail in the quench".

When I did the gear driven trike project, I used helical mitre gears by Boston Gear.
They were available either induction hardened or unhardened.
I would have like liked to use the hardened gears as AK does , but the price was 3 times higher.
So I used the unhardened for the first off. The gears are still OK after 3 summers of use.

I would say for prototype use, AK might be better to just use the 1045 unhardened.
That being better than a patchy profile that looks nice and black,
but can't be tested and probably will be uneven and distorted.
And unless the quenchant is really turbulent into the roots and flanks, they will be soft anyway.