You hear a lot of talk about using brine for quinching but seldom anyone can tell you how to make it.

I was looking at a sheet on hardening and tempering different steels. Many of them called for a 5-10% brine solution. In a little footnote at the back there were directions.

A 5% brine solution is made using 1 pint of raw salt (rock salt) to 9.5 qts of water. A 10% brine solution is made using 1 qt of raw salt to 9 qt of water. They made a warning not to use table salt as there are additives that can cause unwanted reactions in the steel.

The "traditional" method calls for adding salt until it's strong enough to float an egg---probably a fresh laid one and not one that's been drying in the refrigerator for a while...

Thomas

I guess it depends on what you are quenching. I fooled around some with 1050 for tomahawks. JPH, he know his stuff. He told me to use a saturated (will no longer dissolve anymore salt) solution, with a couple squirts of dish soap to lessen the surface tension. I wrote it down for future reference, but ended up remedying the problem by quenching warm water for three seconds, then going to warm oil (quench oil should always be warmed to about 130 deg F for quenching) for the rest.

I want to add something else about the warmed oil quench. People ask me all the time how warmed oil is a faster quench than cool, room temp oil. It has to do with the thickness or the viscosity of the quenchant. The thicker the quenchant is, the slower it quenches the piece. What happens when you heat something?....The parts that make it up begin to move faster. When the oil is warmed up, the little parts that make it up begin to move faster, this makes it thinner and more viscous which makes it a faster quench. You can actually see the difference of the thickness of the oil with your own eye. Try this and see. Put a stirrer in room temp oil....lets say 70 deg. F. Lift the stirrer out, and watch the oil drip. Take note of how thick or thin it is. Then, do the same thing with oil that has been heated to 130 deg. F. Notice how much faster it runs off of the stirrer and how much thinner it is.

Now, back to the topic!

I am also interested in salt brine as a quenchant, what would be a good mix for a 5 gallon bucket?

Table salt,
I believe the only difference between table salt and rock salt (and somebody please correct me if i am wrong...i am remembering this from highschool) is the addition of Iodine. If you use non-iodized table salt (it's usually right next to the Iodized stuff at the market) it should be the same as rock salt.

Apprenticeman: If you go by the above proportions it would be 4.5 gallons of water and 1/2 gallon of salt for a 10% solution or 4.75 gallons of water and 1 quart of salt for a 5% solution. I've personally always done like Tyler and dissolved salt until it was fully saturated...
-Aaron @ the SCF

2 cups=1 pint
2 pints=1 quart
4 quarts= 1 gallon

Adding salt to water, up to the saturation point, will not change its volume; only it's sp/gravity. It should not be nessary to reduce the volume of the water to get the salt to "fit". you can put almost a 1/4 cup of sugar in a full cup of water.

on spacific waight- fresh water weights 8.34 ppg-saturated brine weights appx. 14 ppg-so you can add about 5 1/2 # of salt to 1 gallon of water. as a compareson sea water is about 9.4 ppg

Many, Many years ago an old timer who was known for his hardening and tempering ability, told me that difference between water and brine was the size of the bubbles formed from the steam the hot piece makes when immersed in the solution. Some of the tool makers I know use a 1/4 inch of vegetable oil floating on top of the brine to take the shock off the item. It also has a tendency to remove the water from the item as it comes out of the quench.

Many, Many years ago an old timer who was known for his hardening and tempering ability, told me that difference between water and brine was the size of the bubbles formed from the steam the hot piece makes when immersed in the solution. Some of the tool makers I know use a 1/4 inch of vegetable oil floating on top of the brine to take the shock off the item. It also has a tendency to remove the water from the item as it comes out of the quench.

Robb Gunter's lye-based Super Quench formula yields similar results but is somewhat dangerous to use. I was quenching tools in a batch several years ago and wound up burning my lungs with the vapor. I now use his revised recipe which is basically salt, Dawn and water (although I can't remember the proportions off the top of my head).

I was also told that brine forms a smaller steam pocket than plain water.

One thing to remember is to balance the steel type with the proper quench. Plain water hardening steels will get hard as a banker's heart in a brine quench because the austenite is turned to martensite so quickly. In fact, garden variety A36 will often get in the Rockwell 40 range in brine. However, typical air hardening steels like S7 may be harmed by a rapid quench due to excessive stress.

Yes 1234567

Plain water makes larger steam pockets, which is an insulator. It's also a reason why thin items warp in the quench - because some areas are cooling and others are being insulated so stresses develop.

Agitation is the key - a falling column of water works well so if you had, for example, a six inch pipe coming out of a large cistern, you could get a piece quenched pretty quickly if you could dump the water on the item.

Brine is, shonuff, faster than water.