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4V Heat Treat Questions

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Samuel Goodhue, Apr 25, 2020.

  1. Samuel Goodhue

    Samuel Goodhue

    Nov 26, 2018
    Hey all,

    I've been making knives for about 3 years. Have had great results heat treating 1084, AEB-L, A2, 154CM, 5160, and 52100. I've failed multiple times over the years with 15n20 however, and Im coming off a frustrating losing streak of 3 failed blades, so I really want to get this 4V small EDC blade right the first time.

    Can't find much in the way of HT recipes online, so I'm planning on just going off the Crucible data sheet. Plan is to foil wrap the blade and austenitize at 1950F for 30 mins, plate quench with forced air until cool enough to hold, subzero treatment in dry ice slurry for a couple hours, temper twice for 2 hours each at 1000F.

    I can't find much discussion on 4V heat treat online and would really appreciate input from people with experience with the steel.

    Also, I do most of my bevel grinding pre-HT. With 4V, will the plate quench with compressed air be sufficient to get the blade, including edges, hard? I've heard mixed opinions, but have had good results with this method on most air cooled steels.
    I'm really hoping to avoid having to a) rough in bevels on hardened steel or b) try and get my 1950 degree blade out of its foil pouch and into quench oil in a second or two.

    Lastly, from this little bit of discussion that I've found online, people seem to be doing a Ln2 Cryo treatment. Think I can get decent reduction in RA with just a dry ice bath, or do I really need L2n for 4V?

    Thanks in advance for the input.
  2. Seedy Lot

    Seedy Lot

    Apr 15, 2019
    I have made a couple dozen 4v blades. All of them have blown the minds of the clients and the clients are users of knives and have plenty of customs. 4v can handle a very thin edge with amazing results so design accordingly. I have been austenitizing at 1950 with a 30 minute soak and plate quench. I then have been using 3 1000 degree tempers 2 hours each. Blades have been in the 62-63 rc range. No cryo or sub zero and phenomenal results in real world use.
    Samuel Goodhue likes this.
  3. rodriguez7

    rodriguez7 Gila wilderness knife works

    Feb 1, 2009
    If your using high tempers, you don’t need dry ice or liquid nitrogen. High tempers are enough to eliminate most retained austenite!
    Samuel Goodhue and hugofeynman like this.
  4. Larrin

    Larrin Gold Member Knifemaker / Craftsman / Service Provider Gold Member

    Jan 17, 2004
    Dry ice is fine. It hardens great with plate quenching. I prefer low temper for improved toughness. Try 1850F for 30 minutes, plate quench, dry ice, temper at 400F 2x 2 hours. Should be 62+ Rc.
  5. Samuel Goodhue

    Samuel Goodhue

    Nov 26, 2018
    Thanks Seedy Lot, rodriguez7 and Larrin! Appreciate the HT recipes and the tempering advice.

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