Hardening mild steel

[Old Ford2]

Very interesting read, for something that I thought not practical,  other than "kasenite"
Please "google"  " Rob Gunter  Super Quench "
I have not tried it, but look forward to doing so.
I hope this helps some of you "gun makers"
All the best!
Fred

[Acer Saccharum]

Mild steel rasp, casehardened in a charcoal pack and water quech. It's a honey of a tool, just made it as 'play' to test out if casehardening really works.

[rich pierce]

It looks like a gnarly flame. That it works too is a bonus!

[WadePatton]

here's a current link to the story, recipe, and process.  

http://magichammer.freeservers.com/robb_gunter.htm


and here's a copy:

Robb Gunter's "Super Quench"

5 gal water

5 lb Salt

32 oz Dawn (blue) dishwashing liquid (28 oz if it says "concentrated" on the label)

8oz Shaklee Basic I or 7oz UNSCENTED Jet-Dry or other surfactant (like Simple Green) of appropriate quantity for 5 gal mix (wetting agents)

The Jet-Dry (or whatever you use for a rinse agent) does something chemically to the surface of the steel. It allows the salt in the mix to start attacking it as soon as it hits the air - make sure you have a LOT of clear water to rinse in ready at hand. These surfacants are wetting agents. They break down the surface tension of water allowing it to make contact with a material.
We've all dipped a cold piece of metal in water and seen a bubble-like "skin" form with dry metal under it. This is surface tension trapping a layer of air, it makes a fair heat shield. In a quench, steam will form a similar surface "skin" and prevent full contact with the water, insulating the steel from a proper chill. Wetting agents prevent the "skin" from forming.
Detergents do a somewhat similar job, they're emulsifiers allowing oils and water to mix. This prevents any oily residues from the fire from forming a "heat shield" surface layer. The salt in the water raises the specific heat of the water and draws the heat
from the steel faster.

Stir it up to get it moving before you quench. Don't quench anything with more than 45- 50 points of carbon. Will harden mild steel to Rockwell 42-45 (in spite of common wisdom that says you can't harden mild steel).

It's color coded - when you've exhausted the usefulness of the quench, it'll shift color from blue to green.
____________________________________

www.shaklee.net
The Forgery School of Blacksmithings'
SOAP SOLUTION QUENCH
For mild and low carbon steels

Whether its on the internet group "theforge", at ABANA chapter conferences, or just general discussion between a couple of friendly smiths, when the subject of Robb Gunter's "Super Quench" comes up, most of it is fact, but some of what is passed around is erroneous. Yes, there are some errors, but generally minor. There is often a great deal of disbelief as to the efficacy of this Super Quench. Here's what he had to say about it at the Guild of Metalsmiths 1997 Fall Conference:

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. 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.

The above is how I heard it from Robb Gunter at the Guild of Metalsmiths 1997 Fall Conference.  

Dave Brown
Heritage 'Smithing
Heritage Hill State Historical Park
Green Bay, WI  

 

[J.D.]

The Super quench is great for hardening impact tools made of mild steel, to give them a tough resiliency, especially for a specialty, one time use tool.

I doubt it would work well for hardening mild steel frizzens or springs, for example. It might work for giving lockplates some hardness?

[Chris Treichel]

There is also the old method of packing in a can with leather, charcoal and bits of bone and cooking it in a hot fire for a few hours.  Gave it a try a while back on a Indian made frizzen that tested as mild steel and it actually worked. Turned it into a good sparker.

In my case used a tin can filled with the frizzen wrapped in leather bits with some broken up old bones and charcoal. Left it in a roaring campfire for about two hours (give or take a few beers). Let it cool down. Heated it to critical, oil quenched it then tempered it in the oven at 400 for about 3 hours.

[wilkie]

I tried that years ago but used a piece of coat hanger to hold the leather against the part.  Then I put it in a can with another can inverted over the top to keep air out and baked in a forge furnace for about 20 minutes, then dumped the part into cold water.  Found out it hardens outward as well as inwards when I tried cutting off the coat hanger with side cutters.  Finally removed the coat hanger on the grinding wheel after I put two half moon grooves in the side cutters.  And yes the part was case hardened as well.

[Hessian]

I wonder if borax could be used as a "wetting agent" in the "super quench." Seems like it should work in solution. What do you think?
Hessian