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    hardening low carbon mild steel

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    hardening low carbon mild steel

    Post by Hermit on Tue Feb 10, 2015 11:47 am

    I read of a method of turning low carbon steel into low grade tool steel that was used many years ago by toolmakers and blacksmiths.I think it would be ideal for hardening mild steel arrowheads.You need an airtight metal container.A piece of large diameter steel pipe(2ins. diameter minimum,6ins or longer)Threaded at both ends and capped(caps can be obtained from a plumbing supply store)the parts to be hardened need to be placed in the middle of the pipe,and packed around with charcoal,bone dust,small pieces of bone and scraps of leather.The metal container needs to be placed in the middle of a fire such as a forge,a woodstove or even a fire in the backyard.The fire needs to kept going for at least 18 hrs.Keeping the fire going longer is even better.
                                                                                 The way this works,is that the material the parts to be hardened are packed in is carbon rich,and because the steel is being constantly heated,the steel absorbs the carbon from the packing materials and the added carbon changes the mild steel to low grade tool steel.I have not tried this myself(I really should,as I heat with a woodstove)but I am sure that this method will work.Should anyone try this before I do,I this would be a method I could use and I would be more than interested in a posting about the results.One last thing,gardeners use bonemeal as a fertiliser,I would think it could be used as packing material.
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    Re: hardening low carbon mild steel

    Post by c sitas on Tue Feb 10, 2015 3:39 pm

    Hermit; I took a soft frizzen and made it work great using the method you describe. That was an old mountain mans way of getting by out in the sticks. They didn't have common access to a smithy .

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    Re: hardening low carbon mild steel

    Post by Hermit on Tue Feb 10, 2015 3:54 pm

    thanks very much for the info Sitas,as I said in the posting,I haven't tried it myself.Thinking about it,it is a form of case hardening,and as I said,the longer you keep the fire going,the deeper the hardness goes.Given that the cross sectional area of an arrowhead is so thin,I think it likely that this method would harden it right the way through.I think that I really need to try this,as it is  going to be a technique that I will use often.
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    Re: hardening low carbon mild steel

    Post by Hermit on Tue Feb 10, 2015 3:59 pm

    Using the method I described,you could probably harden 5 or 6 arrowheads at a time.......makes it more time and cost effective
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    Re: hardening low carbon mild steel

    Post by Rizzar on Tue Feb 10, 2015 4:07 pm

    What you describe is case hardening by carbon enrichment (or even color case hardening if focused on the optics by differential quenching).

    The only thing you do is apply a really thin layer of hardened surface, so quite ok for mechanical purpose (wearoff prevention), but not impact relevant hardness.

    Why dont you just get yourself some steel you can harden the easy way or get along with low hardness mild steel???

    The method you describe is complicated, very expensive and in no way suitable for arrow heads.

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    Re: hardening low carbon mild steel

    Post by c sitas on Tue Feb 10, 2015 6:24 pm

    Hermit; It's been a while since I done this BUT, I distinctly  remember all I used was an old boot top for the purpose of the carbon." Leather ". All we're trying to do here is help hold an edge. At best , broadheads are a " one time shot". Surely this is not expensive.Oh ya, I also used an old pint paint can for my container. That baby would through a great shower of sparks, no more misfires  in my old flint.

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    Re: hardening low carbon mild steel

    Post by Hermit on Tue Feb 10, 2015 7:48 pm

    Sitas,I completely disagree with Rizzars post.He states that this method is expensive,you just proved that it's not.He states that this method is complicated,it's not,anyone who can't screw on 2 endcaps,pack a tube with bonemeal,charcoal and leather scraps,light a fire and keep it going for 18hrs.I don't want to be around,they are dumb enough to be dangerous!He suggests that case hardening cannot be done deeply,also not true.I know of a company that will case harden to any specified depth up to .060.thou. of an inch,that would be ON BOTH SIDES,total depth of case .120 thou.(3mm).One chunky arrow head!.In this case,the longer the fire is kept going,the deeper the case.He obviously has no idea of the supply and demand problems faced by people who live in Northern Canada,or rural U.S.A. if he did he would understand why we improvise,and usually manage to find a way to skin the cat.
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    Re: hardening low carbon mild steel

    Post by c sitas on Tue Feb 10, 2015 7:58 pm

    Hermit, I didn't think our kind existed any more . I'm no expert on any thing,  but I'd be willing to make do with any one and on most things.I would never, on purpose tell someone something that could end up harmful to them, all though now days you have to be really on your toes so to speak. No common sense any more.  Good to hear from ya.

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    Re: hardening low carbon mild steel

    Post by Rizzar on Wed Feb 11, 2015 12:14 am

    Economic viability is the thing I wanted to point out.
    No reason to react impolite.


    Running a fire for several hours to get into the desired depth is not expensive compared to find some more adequate material and using normal hardening???

    Time, coal and gas are the things much more expensive than small amounts of metal.


    Putting a relative little amount of small things in "sealed" boxes filled with a special mixture of coal and heating up over several hours before quenching is a complicated thing compared to standard hardening.


    I know exactly the method you want to use and absolutely admire it for machine/gun parts, but its just not viable for arrowheads.
    Deeper hardening is possible, but you will need a much longer diffusion time for the carbon. Easy rule, doubled depth requires quadrupled heating time.
    Professional case hardening can be "deep" (mostly refered to bigger objects), but have you asked about the pricing those professional companys demand due to high (time/energy) efford??


    Besides one very important point you just stated:
    It is a one shot item. I do not think you are planning to shoot armored knights charging you?
    Even in medieval times I state any available steel quality was used.
    I even heard about hunting with copper, flintstone or antler/bone heads before that, so my 2 cents: you should not bother about using mild steel.


    Are there no car repair shops around you? someone that throws away old car springs? simple spring steel makes decent knives and of course arrowheads...

    Have a look at knifemakers around rural areas, i do not think they have problems to order adequate steel anywhere in the world.

    If you want to make gun housings or case hardened mechanics I would be very exited about your attempt.
    It would be the right decision for high ductility in the core and a good surface hardness.


    But it is simply not practicable with a certain chance of poor results for arrowheads.

    But try it...

    Rizzar


    Last edited by Rizzar on Wed Feb 11, 2015 4:39 am; edited 1 time in total

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    Re: hardening low carbon mild steel

    Post by Andy. on Wed Feb 11, 2015 1:33 am

    I've read a bit about the cheap, and readily available, product "Cherry Red" for easy case hardening. Keen to try on mild steel crossbow trigger sears.

    Anyone have experience with this powder or similar??

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    Re: hardening low carbon mild steel

    Post by Rizzar on Wed Feb 11, 2015 4:36 am

    Read about casenite (cherry red) some years ago.

    Have always been curious about it but never tried it since it was easier for me to use leftovers from spring steel or tool steels for trigger mechanics.

    It is not so common around here so I did not have the opportunity to order some for fun.

    But I am sure it works good for its purpose.



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    Re: hardening low carbon mild steel

    Post by mac on Wed Feb 11, 2015 7:58 am

    The important thing about case carburizing is that it relies on diffusion, and thus is very strongly dependent on temperature.  When you plot depth of carburization for a given temperature against time, the time scale is logarithmic.   This means that a result that takes a couple of hours at yellow heat may take weeks at red heat.  

    The other thing about the process is that resulting surface will be very high carbon steel.  This is great for frizzens, but it might be "too much of a good thing" if you are making a bow. 

    Now, that said...  I know someone who spent most of (someone else's) acetylene tank and a couple of hours running a rich sooty flame over his mild steel bow.  The result really was a working crossbow, but it was not set up to draw very far.

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    Re: hardening low carbon mild steel

    Post by c sitas on Wed Feb 11, 2015 8:26 am

    I've read  about the cherry red mentioned here. Bad thing is I don't know someone who has it. Another thing is, the company will warranty the results BUT, it cost like over $200.00 for a 5 gal. pail. They don't sell smaller amounts, so I guess that's a dead end. Todd the archer on here mentioned he tried the old sugar method that was supposededly used my one of the great crossbow  people,now deceased. He said it worked great for him . Others said nay. I guess it boils down to try what your heart and pocket book can handle, as long as no one is endangered by your goings on.I don't like throwing money at a problem, sometimes it is cheaper to buy, but not as much fun.

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    Re: hardening low carbon mild steel

    Post by Hermit on Wed Feb 11, 2015 9:20 am

    Life and what we can do with it seems to be determined by 2 factors,time,and money.We never seem to have enough of either.When it comes to hardening metal,we need heat,and in today's world conventional energy to supply that heat is not cheap.There are ways to supply cheap heat if you look for them.Probably the most available source of cheap heat is used engine oil.In order to burn it,you need a furnace.Making a waste engine oil furnace is neither  difficult nor expensive.A waste oil furnace can be built entirely from readily available scrap materials and used engine oil can often be obtained for free.The heat output from a waste oil furnace is high enough to melt iron.Such a furnace can also be used for case hardening and hardening steel.Because you would be building the furnace yourself,adapting the design to one suitable for hardening crossbow prods would not be difficult.All of the information required to build such a furnace is available on you tube and the internet.As the saying goes,nothing in life is for free,and while it is possible to build and operate this furnace for free,you are going to have to invest the time it takes to build it and learn how to use it.
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    Re: hardening low carbon mild steel

    Post by Anatine Duo on Wed Feb 11, 2015 9:20 am

    I`ve wanted to try the carbon migration method but it takes both time and temperature, as in hours at 1400F, and overheating grows grain.

    Scrap steel is fun but without an analysis you don`t know what alloying elements are there which might be unsuitable for maintaining sharp edges, or what austenitizing temperatures to use, or how long to soak, or how fast to quench...

    but still fun.

    Other options for hardening low carbon steel are work-hardening (dislocation based increase in strength) and also Superquenching (google that for more info than most want)

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    Re: hardening low carbon mild steel

    Post by Hermit on Wed Feb 11, 2015 9:48 am

    Rizzar my friend,I'm sorry,but you just don't understand.Living in northern Canada and parts of the U.S.A.. is not like living in Europe.We can't just go down the road and pick up the things we need.I ordered a ball ended end mill cutter the other day.The closest supplier for this size and type of endmill is in Ontario,3000 kilometres away.The freight cost will be about half the purchase price and I will be lucky if it arrives here in a week.We don't look for alternative ways of doing things using locally available materials because we want to,but because we have to.Living here is like being in the military,it's a way of life you can't understand unless you've lived it.
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    Re: hardening low carbon mild steel

    Post by rolynd on Sun Feb 15, 2015 6:02 am

    Compounds like Kasenite are usually based on yellow potassium ferrocyanide + Carbon source , they are sprinkled on the heated part and be give a short soak time. these will usually produce only a very very shallow depth of carburized material on the surface to increase wear resistance and do not add in the structural stability.  
    With Pack carburizing a far greater depth of carbon penetration can be achieved. And a hardened "shell" of 1-1,5mm carburized material on an arrowhead will also add in its stability on impact.

    Charcoal alone will work , as will leather scraps but now adays normally a additional catalyst is added to help the carbon mirgrating. The catalyst is usually Barium carbonate plus a bit of sodium carbonate and calcium carbonate.
    Sodium carbonate alone as a catalyst will work but can sometimes produce pitting on the steel especially if too much is used . 
    Barium carbonate may be hard to get and is also classified toxic but sodium carbonate should be easily avaliable (washing soda) and is not toxic. Calcium carbonate can also be easily had from ground seashells, limestone, marble etc.
    finely gound charcoal mixed with the catalyst and formed to small pellets witha binder like oil or tar works better than large lumps of charcoal.

    There are many recipes out there, just do a google search for "case hardening and barium carbonate" or case hardening sodium carbonate". A starting point would be about 10% catalyst 90% charcoal. But some recipes go up as far as 40% of catalyst. Well, you got to experiment a little, since it also depends on the steel, time and temperature you use.




    Before I would resort to pack carburizing I would try to use a faster Quenchant fot your steel. Depending on the carbon content a very fast quenchant is able to harden steels that would not harden im Water normally.
    If the carbon content of your mild steel is very very low it may not work but its said that super quench  is able to harden steels like 1020 (0,2%C) which you cant otherwise harden in water or oil. 
    If you also cannot get the ingredients for the super quench there is still the posibility to use a 20% concentrated sodium hydroxide solution  (lye) as a quenchant, but this was banned from use in the industry for some reasons because it is dangerous, do not inhale the steam/fumes and if you get some lye in your eyes you can go blind easily. So do this only as last resort at your own risk.!!





    Before the Bessemer process made it feasible to effectively control the amount of carbon in steel, blacksmiths generally had only iron or tool steel to work with. The Bessemer process gave the steel manufacturers the ability to produce steel in a variety of carbon levels. Mild steel (1005, 1018, and the like) was touted as the all purpose steel destined to replace wrought iron. The manufacturers claimed that it was also suitable for many tools, but that it should be quenched in a solution of sodium hydroxide. 
    At Sandia Labs, Robb and his cohorts experimented with this lye quench and, a bit to their surprise, they found that mild steel hardened considerably more that expected. Metallurgists and others will tell you quite readily that mild steel won't harden. It may get a little harder than if annealed, however it doesn't harden in the typical toolmaker's sense of hardening. Generally speaking, in a plain water quench you shouldn't expect to get more than Rockwell ratings in the low to mid 30's. Robb found that the sodium hydroxide quench resulted in average Rockwell ratings in the 43-45 range, with an occasional test result as high as 48. 
    So, Robb started using this solution at Sandia Labs, but installed a vented hood system over the quench tank. This stuff is pretty harsh and the need for a vented hood was a no-brainer.
    Then OSHA arrived on the scene and insisted that the use of the sodium hydroxide solution cease. The result was that Robb and the Sandia Labs metallurgical lab crew went to work to find a replacement solution. It had to give hardness results comparable to the sodium hydroxide solution, and it should be bio-degradable if possible. The result of their experimentation was what is now generally referred to as Gunter's Super Quench. The formulation is as follows: 
    • 5 gallons of water (This a good volume to work with for quenching, and there are plenty of buckets and pails around just the right size.) 

    • 5 lbs table salt (plain or iodized, canning salt or rock salt, it makes no difference.) 

    • 32 oz Dawn Liquid Dishwashing Detergent Blue. 28 oz if the label says Concentrated.(Blue was chosen because that's what happened to be available at the moment. It was noted later on that as the solution deteriorated to the point that it should be disposed of, the color slowly changed to green. Hence, the blue detergent is recommended. Any other blue colored liquid detergent could work just as good.) 

    • 8 oz Shaklee Basic I. (The solution needs a surfactant to maximize contact between the solution and the piece being quenched. Amway Basic H will also work. Your local farmer's supply should be able to help here, as similar surfactants are used to facilitate the distribution of fertilizer in soil. In response to a question from the viewing stands, Robb said that just about any wetting agent should do, even the stuff photo film developers use. Just follow directions on amount of agent to be added to a given amount of water, then scale up or down to the 5 gallons of water used in this formulation.) 
    Heat your iron to 1550 degrees Fahrenheit, and quench. No tempering is needed. 

    So, he mixed up a batch right there in front of us and used it for his next demonstration. He took a piece of 1/2" 1018 and cut off a piece about 3" long. This piece was heated in the gas forge, and a cold chisel end was forged on to it. Robb heated the piece to 1550 (critical temp for mild steel), and quenched it in the solution. He then took his new "chisel" and proceeded to use it to cut almost through the parent bar. Then, he did it again. The cut bar and the chisel were passed around for all to take a good look at. The edge on the chisel was not deformed in any way. The top had not mushroomed, nor did it even show any evidence of having been hit with the hammer. But, so as not to mislead us, Robb said that a chisel of this type might be good for 7 or 8 cuts maximum. He recommends this quench for tools such as spring fullers and many treadle hammer tools/dies/fullers. He showed, and used, one such spring fuller that is made of mild steel and quenched in the solution. He has been using this particular fuller for several years with no ill effect. The fuller is unmarred, and the spring is still strong. 
    I was impressed, to say the least. I was not the only person there who was "wowed" by this little "trick". Robb said the quench is good for anything up to 50 points of carbon. Above this carbon level this quench should not be used. 

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    Re: hardening low carbon mild steel

    Post by Hermit on Mon Feb 16, 2015 9:12 am

    thanks Rolynd,this is info. I can use...................
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    Re: hardening low carbon mild steel

    Post by c sitas on Mon Feb 16, 2015 6:59 pm

    This is something I will have laying around in a 2 gal. plastic container I have. 
    when you make a part and finish it, just heat her up good and drop it in the bucket ,so to speak.I've never tried Rosey Red , the company warranties the stuff to do what they say.  This stuff sounds like a similar process ,with similar results, for a lot less money.I'm not looking for a miricle but, you never know.Thanks guys.

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    Re: hardening low carbon mild steel

    Post by c sitas on Mon Feb 16, 2015 7:05 pm

    Sorry guys but, -now that I'm yaking, Would it be best to have hard  metal rub on hard metal?Or have some hard and some soft .I'm talking about a trigger and the pressures it takes on.

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    Re: hardening low carbon mild steel

    Post by Gnome on Tue Feb 17, 2015 6:33 am

    Ideally you want both surfaces that interface at high pressures to be the same hardness, or the harder will wear out the softer. I'm not sure how hard they have to be for the pressures involved, but I don't think making them harder than they have to be ever hurts, so long as the surfaces are the same.
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    Re: hardening low carbon mild steel

    Post by Hermit on Tue Feb 17, 2015 1:15 pm

    On a sear and notch type trigger mechanism the sear tip and the notch should be hardened and then polished.Any adjustments should be made with a very fine stone,either diamond or natural stone.Hardening is done mainly for the wear resistance. The sear and notch on a crossbow is subject to high stress,which will cause wear.I have seen more than a few builds on here where I am sure that the trigger mechanisms are not hardened.The builds work,and the builders seem satisfied.Over the long term,I don't know how long an unhardened trigger mechanism will work before needing overhaul or repair. It's probably not a concern to the builder,as having built the mechanism,making a new sear for example won't be a problem.
                                                   If you are planning to put thousands of shots through your bow,you will want your trigger mech. hardened.Practical experience has shown that while it is desirable to have a hardened trigger mechanism,an unhardened steel trigger mechanism will work satisfactorily for normal usage.
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    Re: hardening low carbon mild steel

    Post by Hermit on Tue Feb 17, 2015 1:51 pm

    I forgot to point out that having 2 unhardened surfaces working together is better than having one hard and one soft.
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    Re: hardening low carbon mild steel

    Post by PierreC on Fri Feb 20, 2015 1:21 pm

    Since it is unlikely that two shop-hardened surfaces will be of exactly the same hardness, it might pay to deliberately temper one of the two wearing surfaces slightly softer.  For example if your particular trigger mechanism would become harder to fire should the trigger surface wear, but be prone to accidental discharge should the sear wear, it is obvious to limit all of the wear to the trigger.  It is pretty common in machine tools with sliding surfaces to have a sacrificial part that is easy to make take up all of the wear, while hardening the more expensive or difficult part.

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    Re: hardening low carbon mild steel

    Post by 8fingers on Sat Feb 28, 2015 10:19 am

    I saw an article where the object was to color case harden gun parts. My recollection was the authors container of choice was 2 small flower pots sealed with clay. The part was packed in charcoal, as I recall powdered briquettes. When heated to desired heat / time, the flower pot crucible was broken over the quench tub and everything dumped in at once. The brine used was a strong potassium nitrate solution. and it was vigorously aerated using a bicycle pump connected to a perforated tube in the bottom of the tank. 34-0-0 fertilizer or the granules found in instant cold first aid packs will work.  More air equals better colors. Reusing the charcoal was highly discouraged as it was now essentially 3/4 of the way to being gunpowder, highly flammable with out adding sulfur. I believe Birchwood Casey ( Brand) sells small quantities of hardening compounds. Brownells.com has 'Surface Hardening Compound' in 1 Lb. tubs,

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    Re: hardening low carbon mild steel

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