Nitralloy N AMS6475 2

[mfgenggear]

Does any one have some material that would like to sale. a small amount, like 3' long.

I need to run some Heat Treat(Harden,Temper & Precipitation Harden/Nitride Test.
need to work with my Heat treater on cycle time in hours to obtain .018-.024 effective case depth + grind stock.

if any one has worked with this material recently I would be great full if you could pass on any info on the above & inch per inch change if any during the Nitride cycle.

Thanks & Kind Regards.

Mfgenggear

 

[tbuelna]

mfgenggear,

About 18 months ago, I had seven 42" diameter ring forgings produced in AMS 6475 (vacuum melt Nitralloy N) by a forging house in L.A. (Mattco). The forgings were for a large planetary ring gear. Mattco sourced the 16" bar material from Latrobe. The forging house said Latrobe was the only source they could find for this particular material, and Latrobe barely had enough material in inventory (the total material weight for the order was less than 3000 lbs). So I would imagine that Nitralloy N VAR is somewhat difficult to find. But if you call around to some gear houses or forging houses that work with aerospace gears, you might find someone that has a suitable rem.

The ring forgings I procured were delivered with a 1/2" thick prolong, that itself was used for our metallurgical verification. If all you need is a small sample for metallurgical process development, I might be able to saw off a section of the prolong for you.

As for growth during nitride, AMS 2759/6 lists "2 to 10% of the effective case depth per surface".

If you need further guidance on heat treat beyond AMS 2759/6, I would recommend calling Latrobe. I have spoken with their metallurgists about this specific material and they were very helpful.

Regards,
Terry

 

[mfgenggear]

Terry

The material is almost non existent, how ever I did find some material from one of our customers. otherwise this material requires a mill run from Latrobe.

I did discuss the material with a Latrobe Engineer, however this was enough to get some one in trouble.
I need actual runtime data. which I will proceed with when I procure the material.

Did you take any dimensional measurements before & after of the ring gear?

Thanks for Your recommendations

Mfgenggear

 

[tbuelna]

mfgenggear,

I don't have any further information for you. Unfortunately, the ring forgings are still sitting on a pallet in the bond room, covered with oil (and dust).

For this particular ring gear design, we did not considered growth during nitride to be an issue. We specified copper masking over most of the gear rim/flange surface, since we needed to finish machine these areas to close tolerance after HT. However, the drawback with selective masking is usually more distortion.

Besides AMS 2759/6, I have a good reference "Heat Treatment of Gears", by A.K. Rakhit. In fig 6.1 he gives a curve for nitride effective case depth vs. time. Your lower limit of .018" would be about 42 hours and upper limit of .024" would be about 72 hours. He also recommends keeping the case depth to a minimum, since you will have less distortion/growth issues. I believe there are some recommendations in AGMA for case depth vs. tooth DP. Finally, Rakhit states that if the case depth is .010" or less, the AGMA quality of the gear teeth post-nitride will typically be as good as pre-nitride.

Hope that helps.
Terry

 

[mfgenggear]

Terry

Unfortunately I have to hold the case depth that is on my customers
engineering drawing.. according to the latrobe engineer this material will change/grow .0015 inch per inch on dimeters & .0005 inch per inch on
lengths. I will be selective nitriding an certain areas.
the part is a shaft.

when I run my test I will advise.

Take care
Mfgenggear

 

[batter1979]

Call these guys in PA.

http://www.xaloy.com/sales.html

I used to do business with them. They deal in fairly exotic materials. They may be able to help. If you want nitralloy, you might want to consider hard facing, then grinding. Or pick a material that can be carburized.

 

[Windward]

This is a little off-topic, but I thought it might be interesting to some who read this thread. The article below discusses some new gear materials:

http://www.windpowerengineering.com...ork-for-wind-too/comment-page-1/#comment-7907

It mentions QuesTek Innovations LLC, an Illinois supplier of gear steels. I don't know anything more about any of this and have no relation whatsoever to any company mentioned. Just trying to be helpful.

 

[mfgenggear]

To Who May be Interested

This material is a precipitation Nitride material. so there was dimensional change.

The Material rough turned, the Normalised, Harden & Tempered, then semifinished machine, then Precipitation Nitrided. it was not stressed relieved.

The areas that are Nitrides changed as much as.0019" inch per inch.
OD changed to the minus. in other words part OD's contracted.
the non Nitrided diameters changed very little.

length change also contracting, .00049" inch per inch.

This Material is very unpredictable & recommend your own test.

Take Care

Mfgenggear