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  1. #1
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    Question quenchants for 5160

    I had an accident with the tranny fluid that I normally use for quenching my blades (reversed a lawnmower into the tank while moving stuff around ). So I got some cheapy vegetable oil from the stupidmarket and used that instead.

    the oil is quite thin anyway, but i still preheated it to about 130F and carried on as usual with my grund out O1 blades and forged coil spring (5160?) blades.

    I have just found that they are to brittle for me to be happy, even with a low temper (c 55RC).

    I thought it was my forging, but its not
    I thought it was the tempering, but its not
    I guess it must be the quenchant. Only the hardened portion of the blades is getting brittle.

    What do other people use with this stuff?
    Don't just tickle it...


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    Re: quenchants for 5160

    http://www.ajh-knives.com/metals.html#metal26

    55HRC sounds a bit hard judging by the info here

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    Re: quenchants for 5160

    "... and is also used for hard use knives (hardened up near the 60s Rc)"...perhaps not..

    I've used cheap veg oil to quench O1 without any problems, I don't preheat it tho.

    How does the brittleness manifest itself? Are the edges chipping? Does the problem occure with both the O1 and the 5160?

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    Re: quenchants for 5160

    If it IS 5160 that your using.....

    I use warm peanut oil....and triple quench....I have never had a problem with it. Its a good steel and is often a good choice for heavy duty knives that see a lot of abuse.

    couple of questions

    How do you define 'brittle'?.....do you mean edge chipping?

    What are you tempering temps and times?

    and how are you measuring the Rc hardness?...
    ...formerley known as "coutel".

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    Re: quenchants for 5160

    Quote Originally Posted by MushiSushi
    http://www.ajh-knives.com/metals.html#metal26

    55HRC sounds a bit hard judging by the info here

    The quote from that link says it refers to "usual practice for leaf springs"

    and gives tempering temperatures as between 800-1300F for a RC between 38 and 44 Rc..... ok for leaf springs...

    It then says for swords it recommends around 50Rc ,and for knives around 60Rc...

    I havent used 5160 for sometime , but my temper temperatures are between 350 F(low end) and 450F (high end)..triple 2 hrs soaks.
    Last edited by Kevin; 09-05-04 at 10:08 PM.
    ...formerley known as "coutel".

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    Re: quenchants for 5160

    Hi Kevin,

    how exactly do you achieve your triple quenching, is it just a case of quench, reheat then quench again? I've done three lots of quenching with tempering in between before but anly...ahem...by accident. I was wondering if it could be made to work with a clay coat.

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    Re: quenchants for 5160

    Quote Originally Posted by narsil
    Hi Kevin,

    how exactly do you achieve your triple quenching, is it just a case of quench, reheat then quench again? I've done three lots of quenching with tempering in between before but anly...ahem...by accident. I was wondering if it could be made to work with a clay coat.
    Hi Chris.

    I was triple quenching 5160 by quenching and letting it cool in the oil in between...sometimes overnight.It was a tip that I read in ckd where several tests were made and the steel was sent away for a spectograph analysis

    (here is the ckd link by Ed Caffrey...
    http://www.ckdforums.com/showthread....ht=5160+triple)

    I thought that leaving the steel cool to room temp between may cause problems with the steel streesing and cracking, but I never had any problems. I tested lots of 5160 blades this way and they always performed well.

    In fact, I am begining to triple quenching all my steels now. but rather than letting them cool completely, I now cool to touch ..., heat and quench again x 3.

    ..I have read that cutting performance/edge retention improves.......but I need to do my own testing (v single quenching) to find out myself.
    .
    Triple quenching v benefits is a bit controversal...and many believe its irrelevant....but it doesnt seem to be detrimental anyway.

    How you would triple quench a clay coat?..I dont know....as the clay would begin to fall off after the first. Maybe do a normal triple edge quench...for the first two, then clay coat the last?....use the first two quenches as thermal cycles?........but I am guessing.....and I dont know what effect this would have on the temper line?
    Last edited by Kevin; 10-05-04 at 02:21 AM.
    ...formerley known as "coutel".

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    Re: quenchants for 5160

    Hi Guys. I've triple-quenched the last couple of blades I've made, with a clay coat. My procedure is to normalize the blade, bring the whole blade up to critical and quench the whole blade (no clay at this point), and then repeat immediately. This is followed by a final normalizing heat to prevent any stress build-up. I then clean the blade up, apply the clay, and once it's dry go straight into the final hardening with no further normalizing cycles. Both blades have striking if simple (and non-traditional) hamons. The main aim of multiple quenching is to refine grain size, which is important for the toughness of the unhardened spine as well as the egde holding/cutting performance of the hardened edge.

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    Re: quenchants for 5160

    ok, where to start...

    I'm guessing it's 5160, it comes from the coil springs from a variety of cars and the books all say 5160 'or the like' so it may be that the americans have different sprngs to the rest of us but i doubt it.

    Quenching- single quench into preheated (130F) veg oil until cool enough to handle then into water to room temp. I've been doing this with goo results on O1 for a while.

    Tempering- three cycles of 1 hour at 230C (my thermometers don't have both scales, sorry), leaving to cool to room temp in between.

    Brittleness- after tempering i place the blade in a crack in the workbench and pull on the tang with a pipe just to make sure. The blades have been snapping at 10 degrees or less. The O1 blades return to staight at 45 or so (depending on edge quench or not) and I haven't snapped one yet only cracked the edge. I've not tested edge chipping yet, but what little hacking i have done hasn't shown any chipping.

    Hardness- again only guessing according to the tempering info provided by 'the books' and other techy info. I ordered some hardness files over as month ago but they haven't arrived yet (due mid june)

    I annealed a couple of blades that had already ben heat treated (the rest of the batch had been tested to destruction after tempering at 230C and circa300C) and there doesn't seem to be any permanent damage. I don't understand what's going on? surely if the quench is too violant then the blade will get too hard and crack or become brittle; or I'm getting grain growth and it becomes brittle as a result of teh heating of the steel prior to quenching. Either way the damage should be irreperable but the annealed blades bend like an annealed blade should.
    Don't just tickle it...


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    Re: quenchants for 5160

    If you want to chuck a blade or tempered bit of steel my way, I'll attack it with my hardness testing files...
    Peter

    ethics (Noun, pl)
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    2. the moral fitness of a decision, course of action, etc.

  11. #11
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    Re: quenchants for 5160

    230C is about 446F.

    300C is 572F.

    (The hottest tempering temp I have ever done on an edge is 450F....usualy thats to soft for what I want).
    Last edited by Kevin; 11-05-04 at 03:05 PM.
    ...formerley known as "coutel".

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    Re: quenchants for 5160

    I dont know whats going on either...but will have a few stabs at guessing.

    Could it be that the coil spring your using has a memory and micro cracks, hence failing when you flex?

    Are you going through a thorough thermo cycling procedure before hardening?


    5160 is said to be a good choice for abs style test knives...with a soft or spring back.
    ...formerley known as "coutel".

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    Re: quenchants for 5160

    This is the same problem I was having, and the reason I started triple-quenching to refine the grain.

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    Re: quenchants for 5160

    What are the fracture surfaces like?

    Do they fit back together exactly, or is there some residual distortion? Are the surfaces matt or do they have some shiney areas? What is the angle of the break?

    "Could it be that the coil spring your using has a memory and micro cracks, hence failing when you flex?"-Coutel

    I was going to suggest some sort of work hardening as well, it is certainly a possibility when using old springs. The only other posibility I can think of is that some impurity from the fuel you are using has embrittled the steel.

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    Re: quenchants for 5160

    The break is clean and matt in appearance, I haven't tried fitting back together but it looks as if it should do (i'll try later today).

    After I uncoil the springs I anneal them in the forge when I lock up for the night, just to kill its memory :alcoholic

    When I'm done forging I normalize twice (pointing north with one leg cocked up) and then anneal in ashes, although if I'm on my way home I will do that in the forge on occasions.

    After rough grinding I normalize once more just prior to heat treating.

    I'll try triple hardening some blades over the next few days and if that fails then I guess I shall have to try a thicker quench, see if that works :confused:

    psbond- if you pm me an address I will send you the results of the tests for a hardness check, if thats ok.
    Don't just tickle it...


    dave budd handmade tools knives, tools and courses makin' them! 2014 Course List NOW ONLINE!

 

 

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