C276 Holes 1

[holdpt]

All:

We need to place 1 1/8" diameter holes in some 1" thick C276. What is the best process for this without impacting the integrity of the material? The last vendor we used had no problem with our AL6XN but a world of trouble with the C276 which makes no sense. We found out what too much heat input will do and cannot afford that mistake.

 

[metengr]

Use the following as a guide regarding machining and consider EDM;

http://www.hpalloy.com/alloys/descriptions/HASTELLOYC_276.html

 

[holdpt]

What about any limitations to water jetting these holes? I have not found much information on that.

 

[EdStainless]

Call Rolled Alloys and ask, they fab high alloy.
Sounds thick to water jet to me, but I have been out of the work for a while.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[mrfailure]

The one potential issue with EDM that I can think of is the recast layer left at the surface. This may not be an issue for your application but if it is you may need to specify a limit on allowable recast from EDM. If geometry allows, I'd go with waterjet cutting.

Aaron Tanzer

http://www.lehightesting.com

 

[Guest102023]

Water jet cutting can do the job. Depending on the tolerances, you probably should allow for reaming to size afterward.

 

[unclesyd]

I see no problem with drilling these holes as we have drilled thousands of holes prior to anything like EDM or water jets.
C-276 is very wear resistant and quickly work hardens so use only a very rigided setup and the proper tooling is required. In drilling the operation should be continuous with no stops and starts. Power feeding is recommended. Drill bits have to be sharpened regularly.
I would contact bit manufacturer, like Gurhing, to get there recommendation

 

[holdpt]

We had a Rockwell Hardness done and it consistently read 97.2. I believe C276 should be around 86. Could this have been the problem with drilling holes previously?

 

[unclesyd]

No, I don't think that is the problem as your numbers,
assuming Rb, are at the upper end of the scale and in reality
are not that different. Over the years we learned that the
hardness range of C-276 was not a very usable physical
property. We actually depended on the MTRs for the thermal
history and other physical properties even though these were quite variable in even in the same heat.
As posted above the material is extremely hard, but not
impossible, to machine. I've been trying to find more specifics our machining process.

 

[holdpt]

Thanks unclesyd!

We did a sample production weld for hole testing as well. I didn't let the material reach much over 300 deg. one inch from the weld. I talked to the welding super to see how they monitored heat input and the answer was, "we didn't". Knowing that now, I suspect our issues can be solved.