Rampmaster Operating Manual
Heat Treat ver. RM3 – Feb 2017
Page 24 of 25
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Heat Treating Stainless Blade Steels at Ranger Original Handcrafted Knives
Special Thanks to Rob Ridley of Ranger Original for this Information
We have had a number of people ask us for our “secrets” about heat treating knife blades. While we appreciate the compliment, there really are no
secrets – and what works for us may not be your favored solutions. Here are our recipes. You may copy them, publish them or use them as you please. We
have drawn from various sources, including Crucible data sheets, other steel suppliers and postings on Blade Forums as well as a good dose of personal
experience.
All of our stainless blades get double wrapped in high temperature, 309SS foil envelopes – with double folded seams pressed down firmly. Always put
them in the envelope the same way – so you can put them in spine down and pull them out by the handle, instead of the tip. We use brown paper (no
idea why brown – just what we use) in pieces about 2 x 2 inches. 2 pieces for an average hunter and four for a big bowie. The trick is to use enough paper
to eat up the Oxygen in the envelope – without blowing up the envelope like a balloon.
154CM, CPM154, ATS34
All three of these, heat treat the same. After a full speed ramp up to temperature, they soak 45 minutes to an hour in the Evenheat Oven at 1950F
degrees. Then they get placed – still in the foil – spine down – then flat - on a 1” aluminum plate. The second aluminum plate is placed on top and pressure
is applied. We used to use weights for the pressure, but now we use clamps. You are looking for good firm contact. If you are thinking hydraulics you are
thinking WAY too much pressure. After 2 minutes (or less) they will be hand cool, and ready to remove from the foil for cryogenics. They don’t have to go
straight into cryo, but aim for something less than an hour from plate quenching. We use liquid nitrogen for cryo but dry ice in acetone will also do. The
household freezer is no use at all. They probably only need a couple hours in cryo, but we leave them overnight.
The next morning, they will be in the range of RHC63+. After warming to room temperature, they get tempered. We temper twice at 500F degrees for two
hours each time – to get about RHC61. You can experiment for other hardness's but 61 is a very good target for these steels.
CPMS30V
Same wrap – same temperature (1950F) - same soak time – same plate quench – same cryo as 154CM above. This steel gets double tempered at 400F
degree for about RHC60
440C
Same wrap – Harden at 1900F degrees and only about 15 minutes at temperature – then plate quench and cryo as above. Hardness out of cryo will be
about 61. Temper (twice for 2 hours) at 275F for RHC60 – 325F for RHC59 – and 375F for an excellent RHC57-58.
Questions and Answers provided by Rob Ridley of Ranger Original
Q1: Does Cryo really make a difference.
A1: Yes! It increases initial hardness between 1.5 to 2 points and even though you may temper back to softer levels, the steel has been more completely
transformed to a tough and desirable state.
Q2: Why do you leave blades in the foil to plate quench them.
A2: The really hot blades never see oxygen this way. That means no scale and very little oxide. Air quenching the old way meant going back to the grinder
to clean up the mess. Blades done our way can be cleaned up with just a buffer.
Q3: Why do you remove the blades from the envelope before cryo?
A3: Experience! We like hanging the blades from a coat hanger in the cryo tank. Handle pin holes make that easier. We also found that when a tight foil
bag full of liquid nitrogen, hits the warm summer air, bad things can happen. The low tempering temperatures won’t cause you any scale or oxide
problems anyway.
Q4: Can I use my freezer for cryo?
A4: No. It isn’t nearly cold enough to do any good at all. Dry Ice or Liquid Nitrogen work equally well. Dry ice is easier to handle but only lasts a day or
so. Liquid nitrogen in a good dewar will last a month or more depending on use.
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