re-heat treat 1095 to shrink 1

[Dobe]

I have been trying a new process for our 1095 ring, .057 thick x 1.38 ID x 2.12 OD. We normally stress relieve on fixtures, heat treat, quench and draw. We tried stress relieving without fixtures and my ID grew to 1.140 and my OD shrunk 2.11. It was only 100 pieces but was wondering if I can re-heat treat and shrink the ID?

 

[redpicker]

Are you saying this occurred with only a stress relieve treatment? I am surprised that you would see that much movement with only a stress relieve.

Having said that, I know of no way to accomplish what you want to do. The 0.057” dimension (you call it a thickness, but it is really a height, correct?) is so small that I can’t think of anything to do but start over.

rp

 

[Dobe]

the .057 is a thickness. I am not sure what happened as the Supervisor ran this sample. I am now following a new lot to figure out just what they did. He also ran more parts, the same method and they are all good???? Supposedly. This is what happens when nothing is documented and no data is taken.

 

[redpicker]

Sorry, for components that have an OD and ID, I am just used to thinking that the thickness = (OD-ID)/2. That doesn't work well with your dimensions, so in my mind, the 0.057 would be the height of the ring (perhaps the width).

Re: no documentation, that's an age-old problem. Nobody wants to fill out paperwork, particularly if nobody is going to check to make sure it is done correctly.

rp

 

[dbooker630]

The ending ID does not quite line up with the initial OD, unless the initial was 1.138 and grew to 1.140. Anyway, with the ID increasing the and the OD shrinking, what was the ending thickness, did it increase? Did the cross section show evidence of bowing?

I am not sure what metallurgical properties you need but 1095 steel is a good candidate for austempering, espcially with the size and thickness of your ring.

 

[Dobe]

Parts were stress relieved, no fixtures, just put in a basket. I normally put these on fixtures and are tighteded down. Stress relieved at 1100° for 3 hours. Then put in an amospheric oven between 1500°-1600° for an hour at temp. Quenched in 165° oil for 15s; put in our pre-draw oven at 400°. Depending on hardness then put on fixtures, because they need to be under .002 flatness and drawn to Rc47-52.

We are trying to lighten up the processes to make it faster by not putting on fixtures at the very first op. stress relieve. For some reason my 5 piece sample after draw the ID was larger than normal. Normal is Ø1.138 avg., these were Ø1.140-1.141.

The only thing I can think of is the operator forgot to tighten down the fixture during draw. Our fixtures are heated and the parts are stacked on the fixture and the nut is finger turned and put in the overn until the part and fixture are to temp. Then the parts and fixtures are taken out and the nut tightened with an impact wrench, put back in the over at temp.

I ran another large lot and had great results running as we always run. So something went amiss on our 5 piece sample????

 

[dbooker630]

So the parts are stacked and pressed together to achieve the desired flatness. I would still be interested in eliminating or modifying at least one of the heat treatments. Can you tell us how the rings are made, if they are stamped or cut? The incoming stock should have some type of annealing treatment that if adjusted could improve the flatness in the green condition. Then I still like the idea of austempering and eliminate the stress relief operation. In any case you may be able to take some cost and time out of your process.

 

[Dobe]

Material is STEEL-.060 +.000/-.002 X 3.12 +/-.020 X 96", SAE 1095 ANNEALED
PER AMS 5122 coil.
Right now we are cutting into strips to fit our blanchard grinders because we can only get material at the .060 thickness. Because these parts get plated we grind the strips to .057/.058. Parts are stamped from a die. We rough tumble because of cracking issues and stress relieve because of the grind and punch operations.
We have a lead on some material that is .058 thick so hopefully this pans out and we can eliminate seveal operations. ID and OD tolerances are generous +/-.010, but thickness and flatness are critical. Thickness because plating adds .004, and flatness has to be under .002. A bearing rides on the surface.

 

[dbooker630]

I agree that eliminating the grind operation may improve flatness. Sounds like you are taking the right steps to eliminate variation in your process.