Cryogenic Quenching

Paul Bos · Apr 5, 2001

Eric, sorry I dident get to this sooner, My computer has been down. The freezer I use has a programable controle that steeps down slowley to -280 deg. F. using Liqued Nit.All St/Stls. Are taken down as soon as they hit room temp. from quench, I hold them for a min. of 10 hrs. then bring them back to room temp. the same way I took them down. Then I do a double temper, 2 hrs. per temper.Tool steels are given a snap temper after quench befor I do the Cryo.then they go down the same as the ST.\ Stl. then double temper after. The reason I dont stick them right in the L-N is they could crack from thermal shock, It has happend to me before. Dry ice and alcahol will get you down to -120 to get rid of your retained austinite,but the -250 to-300 will give you better edge retention and toughness. L-N dewers can be found at your local welding store.Hope I have been some help. Paul.

Osbourn · Apr 4, 2001

I don't know if anyone has mentioned this in awhile, but I for one am glad you joined us here, Paul. Thanks for all the great info you've posted.

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Oz

"Come, son of Jor-El. KNEEL before ZOD!"
"Sticking feathers up your butt does not make you a chicken!" -Tyler Durden
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L6steel · Apr 4, 2001

Ditto Oz!! It is so awesome that we have the chance to learn from people like Paul Bos, Kit Carson, Tim Herman, Darrel Ralph, Bruce Evans, JW Smith, Neil Blackwood, Barry and Phillip Jones, and so many others. These people were in the business before I even knew there was such a thing as a handmade knife.

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Take care!! Michael

Always think of your fellow knife makers as partners in the search for the perfect blade, not as people trying to compete with you and your work!
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Eric Shaw · Apr 4, 2001

Paul-

Thanks for all your info! I am in awe of the knowledge and skill required to heat treat properly (and I thought making the knives was the hard part).

Thanks again Paul, and thanks to the Blade Forums.

Eric Shaw

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One Riot, One Ranger
www.shawcustomknives.com

Bruce Bump · Apr 4, 2001

Paul thanks for going out of your way to help us. We all have only the highest respect for you and your expertise on this subject. Please write a book. Bruce B.

Harry Jensen · Apr 5, 2001

Mr Bos-
I want to express my thanks for your sharing your knowledge here on Bladeforums, and Iwould be second in line behind Bruce in buying your book!!!!!
Harry Jensen

cjensema · Apr 5, 2001

Writing a book is a great idea. A lot of us would like to know more about the details of heat treating. I don't want to do my own heat treating, but I do want to understand the process clearly.

Paul Bos · Apr 6, 2001

Thanks Guys, Ill try to answer your questions the best I can, As you can tell Im not to good of a speller. While in High School I spent to much time reading Hot Rod magazins than payin attention to what my teachers had to teach. As far as a book goes id have to have some one to dicdtate to and let them wright it. Paul.