CPM10V HEAT TREAT Problem 1

[gearHTr]

CPM10V gear blanks were left in 2030 deg F. vacuum furnace for 11 hours due to T/C malfunction.

Vendor is looking for a way to determine effect of this on integrity of parts and what testing, such as tensile or charpy, may indicate if parts can be used.

Thanks

 

[gariartola]

Dear gear HTr,

I asume you quenched the blanks after 11 hours isn't it? Or it was a malfunction during tempering?

I asume too that you are looking for comments on alternatives for performing the blank integrity tests.

Anyhow, you could try microstructural analysis and microhardness testing, what is pretty quick and can help avoiding the need of having to machine the test specimens. Look for abnormaly big carbides and big differences of microhardness in different spots of the same part.

If these tests show similar values to the ones you normally have, consider using the parts straight away.

If not, unless you suffer from abnormal carbide growth I don't see a problem for austenizing, solubilizing the carbides again, requenching the blanks and retempering to have them back in the regular state you work at, prior to finishing the part processing.

If you have generated big carbides, then consider running tensile tests and charpys since you might have reduced the elongation and the impact energy of your material, just to make sure that you keep fulfilling your customer 's specs.

Or, to be on the safest side, you can also try to ask directly to the crucible support center:

techservices@crucible.com

since they are who know most about their steel.

Hope you can recover your blanks!

 

[unclesyd]

You had better contact Crucible as soon as possible since they are being dissolved. The last I heard the tech people are still there, especially in the CPM division.

 

[Robertmet]

You may get large grains which is bad and migration of carbides to the grain boundaries which is also bad.Microscopic examination will show both.
Crucible's Pittsburgh facilities have been bought by Alleghany Industries and the Syracuse facilities bought by a group out of Cleveland that says it will continue the Syracuse operation.

 

[Maui]

The Crucible plant in Syracuse has been downsized from over 700 employees to about 50. All of the old timers retired earlier this year before the bankruptcy went through the courts so that they could still collect their retirement benefits. You will have some difficulty finding anyone who is still available that will be able to answer your questions. I believe that Ed Tarney did not take the retirement option. If he is still around he should be able to help you out.

My biggest concern would be grain growth. The grain size is affected by the austenitizing temperature and the time the parts are held at that temperature. Time is less of a factor than temperature, but 11 hours is excessive. You should have a metallurgical examination performed to determine the Snyder-Graff grain size, as well as the carbide size and distribution. Hardness will probably measure out OK provided the quench was performed correctly. But you may run into some toughness issues if the grain size is excessively large, which I expect it to be.

Maui