I have over a 1000 lbs of 4140 2"x2"x8'. What are your thoughts concerning its usefulness as an axe. All these axe videos have inspired me to get creative.

Do you have a powerhammer? If so go wild!

It'll make excellent axes! I've made some very good punches, chisels and knives from it.

Yes I have a self contained pneumatic. Next on the list how have you successfully heat treated this steel? Please only the simple and fast treatment. Temper temp and time. My shop is simple-a bucket of oil,a bucket of brine and a bucket of water. I have an old toaster oven to temper.Thanks to all who answer!

I use it to make axes, a nice, tough steel. Quench them in oil (I hope that's not used motor oil!), and I draw temper between 500 and 600 degrees Fahrneheit. That's more than your toaster oven will likely do. Draw for at least an hour, preferably three. 500 will hold an edge better, 600 will be tougher and resist breaking.

Sure wish I had some of that 2" x 2" bar!

I use combination dies on my power hammer to forge the blades and a 42 ton hydraulic forging press to punch eyes and help align things.

My oil is half motor half automatic transmission fluid. Is this a problem?

if i understand correctly, the fumes from the motor oil are HIGHLY toxic, i have heard of used veggie oil as a substitute

I use the same thing for most of my quenches Banjoe. As anyone that has any real life experience with HT will tell you, Its not a good idea to inhale any fumes, dont let Joshua scare you, tho I am sure that he meant well. You can use the veggie, many do, but remember the viscosity and speed of veggie oil is not the same. Test them out to see.

As a generalisation when hardening steels in fluids,

Water should be clean and fresh from a tap,

warm water will give a much slower rate of cooling but will be somewhat more rapid than oil,

Warm oil is more rapid than cold oil,

Mineral oils are more rapid than Animal oils,

and Animal oils are quicker than Vegetable oils.

If extreme hardness is required, 5% caustic soda solution, or 5—20% brine solution can be used.

I agree with almost everything you said, John, except that mineral oils are faster than veggie oils. I don't think that's necessarily true, and in fact I read a paper a couple years ago (pretty sure it was posted here at one point) suggesting that warm, light veggie oils like rapeseed/canola are nearly as fast as some of the fastest commercial quenches. My own experience has been that warm canola will harden shallow-hardening steels that stuff like motor oil does a poor job on.

I would add that fresh tap water is not the best. Tap water has a lot of entrained air that inhibits quenching. Boiled water or water that has stood for a few weeks is a much better quenchant.

Last time I water quenched I used distilled, but I didn't even think about entrained gasses. Thanks for that tip, Grant.

How much air is entrained? Enough for fish to breath!

I agree with almost everything you said, John, except that mineral oils are faster than veggie oils. I don't think that's necessarily true, and in fact I read a paper a couple years ago (pretty sure it was posted here at one point) suggesting that warm, light veggie oils like rapeseed/canola are nearly as fast as some of the fastest commercial quenches. My own experience has been that warm canola will harden shallow-hardening steels that stuff like motor oil does a poor job on.

The information I posted is recommended standard for UK armed forces working at home and in the field, so I would say that was well researched and not suggested,

Commercial quenches also differ in the speed of quench so it depends on which is being compared to what, and motor oils are a minefield of their own. I try to stick to basics where possible.

I would probaby agree to some extent with Grant, but different water suppliers have different chemicals in the water they provide.

It is always best if you need a specific hardness on a steel, go with the steel manufacturers recommendations, unfortunately most of us don't have access to tempering ovens and soaking furnaces, and have to resort to more hit and miss methods we are familiar with to achieve a desired result.

Oh for the good old days of Whale oil, such is progress.

The more I do this the more I realize that many ways work. I am sticking with my primitive mixture at this time. Maybe someday when the money is right I will buy 5 gallons of aaa quench or one of those industry standards. When I make pattern welds I use 1080 and 15n20. This oil mixture I have seems to get me a good hardness. Thanks for the suggestions.