Time after pre-quench for AEB-L

Hubert S.

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Dec 14, 2019
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I have been using the heat treating method for AEB-L with a 1,725°F pre-quench explained by D DevinT in this thread. With my small oven treating six or eight blades makes for a very long day with the two quenches, subzero treatment and tempering. In this thread from 2018, there was a discussion about pre-quenching one day and finishing the heat treat the next day. @Larrin recommended a snap temper following the pre-quench. I have tried this before and had no problems.

Now, I am wondering how long one could wait after the pre-quench before completing the heat treat. Is there a shelf life for pre-quenched blades or do they keep pretty much forever? Obviously, I do not plan to keep them around forever, but it would be nice if I could pre-quench a bunch of blades one weekend and then finish the heat treat a week or two later, or maybe even a month. Also, I am wondering if there is a recommended time/temperature for the snap temper.
 
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To be safe, it would be better to temper at 1350’f if significant time will elapse between the prequench and full quench. After the prequench at 1725, subcritical anneal at 1350’f for two hours.

Hoss
 

Hubert S.

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Dec 14, 2019
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Thank you for the additional explanation. It sounds like the subcritical anneal after prequench is preferable to the snap temper even if the full quench happens on the next day. I'll give this method a try on my next batch of AEB-L knives.
 

Richard338

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You’re welcome. The purpose of the prequench is to leave more carbides in the matrix before going into the final austenitize, quench and temper. These extra carbides help pin the grain boundaries refining the grain of the steel. A prequench then a subcritical anneal will have even more carbides than just a prequench.

Hoss

Sounds like someone has been reading the Knife Engineering book. Just kidding.
I'm 5 chapters in and loving it, even though I send all my stuff out for heat treat.
 

Hubert S.

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Dec 14, 2019
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795
Time flies, I started this thread in August and I am just now finally getting around to heat treating some blanks.

I just have one last question about that subcritical anneal. What do I do with the blade after I take it out of the furnace? Do I let it cool slowly, or do I plate quench it or something else entirely? Any help would be appreciated.
 
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