hardening low carbon mild steel

First topic message reminder :

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.
                                                               Hermit.

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.
                                                         Hermit.

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. 

thanks Rolynd,this is info. I can use...................
                                                                   Hermit.

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.

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.

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.
Gnome

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.
                         Hermit.

I forgot to point out that having 2 unhardened surfaces working together is better than having one hard and one soft.
                  Hermit.

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.

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,

For some extra pleasure here I've been rereading some of the posts in this thread. I find it amusing and can't help but think that if our for -fathers would have been so reluctant to try something like this,the Indians and the elements would have done them IN.I want to say here also that I have had great luck using delrin with a hard flat anchored in it for the sear.I used 8/32 allen screws and carefully sunk them about 3/4 of the way through the metal. It has well over 100 shots on it and I don't detect any movement of it. I used two screws ,one on each side. I also cut an arc into it to limit the travel. Works a real treat.