1. {Name}
    Welcome to the KKF!
    Please take a moment to register and stop by the New Member Check-In and say hello. We sincerely hope you enjoy your stay and the discussion of all things sharp.
    Feel free to jump right in on the conversation or make your own. We have an edge on life!
    Dismiss Notice
  2. Take a look at our new AUCTION SYSTEM

    This service is available to all KKFora members to both Bid on and Auction off (Sell)items.
    Dismiss Notice

Water vs oil quenching

Discussion in 'The Kitchen Knife' started by strumke, Mar 11, 2016.

  1. Sometimes people add the specific quenching method (water/oil, or even down to the type of oil) when describing knives. Aside from just providing more information, does each one do something different that the reader/purchaser would care about or is it more that providing that level of detail increases the attractiveness of the item because it is more specific?

    Similar question with cryo treatment, is this another thing that really should be standard or is there a reason to look out for those details?
     
  2. butch

    butch Founding Member

    depends on eht steel. there are different speeds of oil. some are nearly as fast as water but then slow after getting the steel past the "nose" (a point you need to get the steel under Y temp in X amount of time to properly harden ) once you pass the nose you can be a bit more gental pulling the rest of the heat out of the steel (greatly helpin gthe steel not crack in quench )
    i fall into the quench as fast as i cann withought breaking stuff camp. read that as get it as hard as i can then temper back. this is a gross simplifying
    oo and side note water quench steels quenched in water have the tiep arc up but qhen quenched in parks 50 (close to the same quench speed at least to 1kf ) the parks 50 blade will have the tip drop. its al a fuction of steel crystallization. in alot of ways the best way to talk to cooks abot steel is to bring up sugar
     
  3. Interesting. So the main difference is the speed in which it cools the blade, which gets the blade harder, but risks it cracking?

    Is it similar to freezing water where the faster you freeze, the smaller the crystals?
     
  4. butch

    butch Founding Member

    im not sure how that part works but i like to think of sugar. if you get to the right temp (dependant on need ) and you quench (at the proper speed ) you make a wholey different sugar product. max temp and speed of quench and then also temper temp and time all play a part
     
  5. XooMG

    XooMG Founding Member

    (removed speculation due to ignorance of ice crystal formation). In steel quenching, you are trying to prevent the decomposition from austenite into ferrite/cementite (lower-stress phases). In other words, cooling slower allows more soft stuff to form before it can be locked in a hard (tense) state.
     
  6. XooMG

    XooMG Founding Member

    By the way, I shouldn't be absolute in the "avoiding decomposition" statement. There are desirable phases that can be achieved by controlling the cooling, but if one is trying to achieve high % in hard phase, dropping temperature quick is the easy way to do it.
     
  7. Thanks, makes sense (although I'm sure there's a lot more to it in total).

    The ice crystal reference is more size rather than composition though. Freezing things as fast as possible makes smaller crystals because you get more nucleation sites and there is less room for each one to grow (think of store bought ice cream vs homemade).

    Thanks!
     
  8. butch

    butch Founding Member

    if you think of the base steel as a net when it comes up to proper temp the holes in the net get larger (jsut so that carbon can slip into the cube ). the crystal itself is slightly inlarged and carbon can pass into it then. when cooled it locks the carbonn in the cube lattice. this is the thing that makes the steel harden (carbon being locked away in the crystal) if the carbon was not there no matter how many heat and cool cycles or the speed of them would ever harden the steel. this is all taking about simple carbon steels and ooo my do things get much more tricky when you get over .84 carbon content or god forbid add extra other elements as carbide formers
     
  9. The quench depends on the steel.
     
  10. To answer what I think was the original question; The quenchant is irrelevant to the end user as long as the maker has HT'd the blade competently.
     
  11. Unless the quenchant is dragon blood. In this case it doubles the price obviously.
     
  12. Don't even get me started on unicorn tears. I had to sit and watch Charlotte's Web over 30 times with that pointy headed f***er just to get a measly 25 ml. Might have to bulk it up with my mermaid milk and hen's teeth solution?
     
  13. Dan, I'm not a quenching professional, but I've heard many times that knives quenched in mermaid's milk would add herring smell to the food. Not a deal breaker if you like fish salads
     
  14. Well, the delightfully named "sperm oil" which was until the 70's a widely used, real-world quenchant, does indeed have a fishy smell. Old timers say it was the best, but perhaps they never tried mermaid milk?
    Or you can go full Ahab;

    "No, no- no water for that; I want it of the true death-temper. Ahoy, there! Tashtego, Queequeg, Daggoo! What say ye, pagans! Will ye give me as much blood as will cover this barb?” holding it high up. A cluster of dark nods replied, Yes. Three punctures were made in the heathen flesh, and the White Whale’s barbs were then tempered.

    “Ego non baptizo te in nomine patris, sed in nomine diaboli!” deliriously howled Ahab, as the malignant iron scorchingly devoured the baptismal blood."


    From;
    http://etc.usf.edu/lit2go/42/moby-dick/794/chapter-113-the-forge/
     
  15. New to the forum, hello to everyone.
    I'm a smith.
    I'm not great with the chemistry but what the Quench does is create a change in crystal structure from pearlite (Soft steel) to martensite (hard steel)
    Some of the stainless steels used in knife making will air or plate quench which pulls the heat out and then they are cyogenically cycled to finish the cooling phase.
    These steels have to be heated to a much higher temp than a simple carbon steel or carbon steel alloy.
    Usually those steels, the carbon ones are heated to around 1500, held at temp for a few minutes and quenched in a suitable liquid.
    The problem with water is that although it is a fast quench and will get steels under the nose, IE the drop in temp in the correct amount of time to make a phase change to martensite.
    The water is very very hard on modern steels.
    So industry uses specially made oils that will quench fast but slow down the cooling process after wards.
    To give you an example.
    Japanese sword smiths quench in water and they are quenching the simplest steel that can be made.
    Basically iron and carbon.
    Master smiths loose 25% of their blades to cracking.
    While, I have friends that make swords who quench in Parks 50 or 11 second oil and never loose a blade.
    As long as the pre-quench thermo cycles were good the blade should survive.
    Also blades like to warp in quench, once you get under the nose you have a grace period to straighten the blade before martensite is grown.
    Oil seems to give you a nicer window to do this.
    So I would say that there is some marketing going on when being told what the quench medium is.
     
  16. Wagner the Wehrwolf

    Wagner the Wehrwolf Founding Member

    Austenite ----> Martensite. No pearlite.
     
  17. Thanks for the addition, yes it is true at temp the steel is in Austenite I was referring to the idea that it before being heated for treatment had been normalized at least and possibly annealed and thus in a pearlite phase.
     

Share This Page