Cryogenic Processing of M2 1

[CryogenIndustries]

I was wondering what experiences other cryogenicist might have had when processing M2 tooling. I recently treated some tooling from the same batch that has had some inconsistent results and thought the base heat treatment may have been at fault, as the cryogenic process and post temper cycle I used has worked on M2 in the past.

I would like to hear other points of view if anyone has one

Thanks

Shannon

 

[Frederick]

There are several avenues for investigation.

1.If you have some untreated parts made in the same batch you can cross section them to determine many things about the heat treat.

2. Cross section a treated piece to determine if there are problems with the metal or with the heat treat.

3. Etch a part to determine if there is grinding burn.

4. Did you do a hardness test before and after?

5. Can you determine if there was a size change in the part during cryogenic processing?

6. Examine worn parts, (treated and untreated) to determine if there is a difference in the wear pattern.

7. Examine your cryoprocessor for problems. Most units out there use a spray bar to cool the parts. If Liquid Nitrogen sprays on to a relatively warm part, it can crack it, especially if it is a very hard M2. I know the people who make these machines will tell you that the nitrogen evaporates before it hits the part, but we have found this to be untrue.

8. What temperature did you temper at,for how long, and how big was the part and how tightly packed in the tempering oven?

9. How many times did yout temper?

10. What cryogenic cycle did you run?

 

[CryogenIndustries]

Thanks for the advise Frederick

I will do the first three suggestions next time we have this issue, last batch we did seemed o.k ( client change heat treater )


4:I did do a hardness test before and after which yeilded little change as expected.


5. No, there was not size change in the part during cryogenic processing

6. Some parts seem to wear in similar places as untreated but with extended wear times, others failure in half the time of the untreated parts.

7. The processor was built in house by my partner and I and i know 100% that thermal shock is not an factor. The chamber deisgn / delivery system is such that liquid can't ever come in contact with items being processed

8. Items tempered at 375 C for 3hours ( as per design spec)

9. Once only

10. Cryo cycle went from room temp to nearing -200 C to room temp over 75 hour period ( incremental drops / rises and soak periods)

Shannon Mafodda

http://www.cryogen.com.au