hardening = heating to a high temp ... followed by a rapid cooling/quenching
Right! The simplest steels can generally be hardened by heating until a magnet no longer sticks to it and then quickly quenched.
it is generally considered better to use as little heat as possible to achieve the desired hardness
Well, each steel has it's "critical temperature" and going far beyond that isn't a good idea. However, if properly quenched the steel will be at its maximum hardness at that point. You don't go higher or lower to achieve different hardnesses. You go above critical, quench, and then draw it back down to the hardness you want through tempering.
that is why ice cold salt water was used in the past as the coolant im sure there is better more high tech solutions now.
I've not heard of ice cold being important, but the most common quenching medium is/was generally oil of some sort. And, contrary to intuition, oil often works better for fastest quenching if it is heated a bit (~150 deg. F) BEFORE dipping your critical-heated piece of steel into it. It will be thinner at 150 deg., and thus flow around faster, drawing heat out more quickly.
with hardening most irons and steels gain in brittleness which in the extreme can shatter on impact that is why iron/steels that have been hardened will often also need Tempering
Hardness and toughness sort of fight against each other. If you try to use your new blade at full hardness it will sure cut well (if you can sharpen it) and it will be very wear resistant because it is so hard. However, that edge will be very fragile and will likely chip with much use. Plus the blade itself will have little flexibility and will snap in two if bent at all.
A blade that's properly tempered will be hard enough to be wear resistant but will still be able to flex without snapping, and the edge can take an impact without cracking or chipping. The drawing back down to proper temper is a balance you have to strike.
which is a heating to a mid/low temp followed by a slow controlled cooling gives the steel a greater flexability/resiliance.hardening followed by tempering is how springs such as might have been used in
medeival crossbows or early firearms may have been made.
Again,
, that's kind of crossways.
1) Heat to critical.
2) Quench. This is shock cooling from thousands of degrees down to below 200 degrees or so in order to freeze the steel in it's hardened phase.
3) Temper: This is a long heat soak at ~400-500 degrees F. to draw the temper down from super-hard/brittle to working hard and resilient. (Exact tempering temperatures are very dependent on the exact steel alloy and what hardness number you're aiming for.)
Annealing is the making softer more malleable often done in a fire by heating to a mid high heat and holding at that temperature for a period of time.
Right. Annealing is heating and then long slow cooling (often packed into heat-retaining sand or whatever) to produce the closest to "dead soft" state so that the steel is easiest to work with tools.
To the original question my opinion is that cheap steel can be made to the highest of quality with the correct and expierienced treatment
Ok, for clarity, there are plenty of steels, and a lot of very cheap mystery alloy steels, which really can't be made into a decent blade by even the best heat treating. Some steels are just not capable of holding a decent, durable edge.
there was even a youtube vid of some guy that tried to outperform a traditional Japanese blade by using modern steels and metalurgy he failed and put his failure down to the skill of the traditional japanese swordsmith taking junk iron and working it into the legendary japanese sword.
I'm not familiar with that exact video, but it certainly is possible that a modern bladesmith didn't exceed some characteristics of an antique blade with the treatment he applied to some modern steel. It is probably not accurate to say that the most appropriate modern steel (there are hundreds) couldn't be chosen and properly heat treated such that it could exceed the edge retention and/or durability of "any" antique blade. There certainly were amazing blade makers in antiquity. It is easy, though, to adopt unreasonable mystical beliefs about what they could achieve with primitive means and materials. They weren't using "junk iron" to make blades, but the best material they were able to find or make -- often combined through various forge-welding processes to bind hard edge material with tough spine metal.
So yes the heat treating used is of very great importance but over most peoples heads and will mean nothing to most of us beyond the quality of the blade in tested use and in my opinion the exact should be said of steel types.
Yes, that is so. The more you study blades and steels and metallurgy the stronger opinions you may develop about blade steels and the more complex and rigorous tests you might perform to prove the specific superiority of this super-alloy over that one.
For most of us, we'd be quite well served by a well-made blade (or six!
) in a simple carbon or stainless steel, and if we just plain want something a bit extra special, we're going to have to take manufacturers' and reviewers' words for it.
