Still happen to have one of these Hanwei Raptor Shinogi Zukuri models.
As new as the day i bought it mid-2014.
The Raptor Shinogi-Zukuri blade, which has evolved as the most common Japanese katana blade design, provides both speed and cutting power.
Featuring a distinct yokote, such blades were originally produced after the Heian period, around 987 AD.
Sales pitch from Cas Hanwei:
Designed under the auspices of cutting master James Williams the Raptor series, Cas Hanwei's new line of cutting katanas, has been created for the cutting practitioner who does not necessarily have access to mats but who wishes to practice and perfect his cutting technique.
The blades are forged in 5160 high-carbon steel and specially heat treated (
marquenched*) to produce very high resilience and greater tolerance of misdirected cuts than a conventional differentially tempered blade.
This steel structure also avoids the need for excessive thickness, allowing the blades to replicate the weight and handling characteristics of Japanese originals.
The edge geometry is configured to facilitate the cutting of both soft and semi-hard materials without chipping, allowing the cutter a wide choice of targets.
Each katana in the series features a unique blade style, each with its origins in Japanese swordmaking history, providing the cutting practitioner with choices in both aesthetics and handling characteristics.
Raptor Series Construction Details:
Blades - Forged from 5160 high-carbon steel, marquenched to an edge hardness of 57 HRc.
Tangs (Nakago) - Full length, double pegged.
Ferrules (Habaki) - Brass
Handles (Tsuka) - Wood core, genuine rayskin (Same), special non-stretch sueded wrap (Tsuka-ito) for firm grip and wear resistance. Raptor feathers hilt ornaments (Menuki).
Guards (Tsuba) - Traditional blackened iron, Raptor motif.
Fittings (Fuchi/Kashira) - Blackened steel, Raptor motif.
Scabbards (Saya) - Wood, non-fingerprinting textured lacquer finish.
*Marquenching is a form of isothermal heat treatment applied after an initial quench of typically in a molten salt bath at a temperature right above the "martensite start temperature".
At this temperature, residual stresses within the material are relieved and some bainite may be formed from the retained ferrite which did not have time to transform into anything else.
In industry, this is a process used to control the ductility and hardness of a material.
With longer marquenching, the ductility increases with a minimal loss in strength; the steel is held in this solution until the inner and outer temperatures equalize.
Then the steel is cooled at a moderate speed to keep the temperature gradient minimal.
Not only does this process reduce internal stresses and stress cracks, but it also increases the impact resistance.
Kevin Cashen on marquenching;
As previously discussed in this thread the idea behind hardening steel is simply not to make any soft stuff as it cools.
The thing is that if you avoid any soft stuff above 900F, from 900F to 450F (assuming folks like carbon as much as I do), things will still be totally austenitic with continuous cooling.
But that austenite will be very unstable and not want to hang around at lower temperatures.
The hardened form of steel that we know so well, caused by martensite, only occurs when a certain temperature is reached, that temperature is known as Ms (martensite start) and it is unique to each steel chemistry since it is heavily affected by alloying.
But for the sake of our conversation I will stick to just carbon in the effects on Ms, the higher the carbon content, the lower Ms.
A steel with around .5% carbon will have an Ms perhaps around 550F while one with .9% carbon or more could be at 400F.
This is due to the stabilizing effect that the carbon and other elements have upon the austenitic matrix, requiring more cooling to initiate the shearing strain necessary for the martensitic transformation.
As we also have discussed many times before, that strain is related to the massive expansion that takes place within the metal as it shifts from the compact stacking of FCC (face centered cubic) to the distorted BCT (body centered tetragonal) configuration.
The most vivid example of this is a katana going into the quench straight and the edge martensite expanding so much that the blade abruptly curves from the expansion.
With all of this movement potential much of our distortion occurs while martensite is being made.
If all of this does not happen evenly and gets enough out of hand we then get the dreaded “ping”.
Also in higher carbon steels there are certain conditions that occur which will results in much lower impact strength and true microfracturing.
When I say microfracturing here I mean truly microscopic, as in within the grains, but less than desirable all the same.
With all this stressing and straining going on you can begin to see why the less shocking we do to the steel from Ms to room temperature the better things could be for the steel.
Water doesn’t offer any mercy in this range and that is one big reason we so often get cracking when we mess with water.
The martensitic transformation is not time dependant, it happens almost instantly once initiated but instead is entirely temperature driven, so if we stop the cooling at any point we stop making martensite.
So while cooling too fast is overkill, cooling all the same really must be continuous.
If we cool fast enough to avoid pearlite, or any form of bainite, we now have accomplished all we needed in the fast cooling and it would be better at this point to slow down.
A very good quenching oil will do this but it is possible to go even slower for the maximum gentleness, this falls within the techniques of marquenching or martempering.
The idea of these techniques is to equalize the entire part being quenched at a temperature above Ms and then proceeding slowly and evenly through the martensite formation.
This does a few things, first of all it is obvious how it can eliminate much of the distortion through equalization, but it will also eliminate large percentages of the stresses involved to typical quenching.
However one of the biggest benefits is what is know as the autotempering effect, when as much as 40% of the martensite forms at temperatures capable of tempering it but remaining within that range long enough for some tempering effects to actually occur.
Marquenching, is properly done with low temp salt baths or specially designed martempering oils, and thus works best with deeper hardening steels, but the technique can be approximated by interrupting a normal quench just above Ms an allowing the steel to air cool.
With salts you simply remove the equalized part and allow it to air cool, but with a normal quench you have to get good at judging the cooling progress to interrupt correctly.
If you interrupt too high you could form undesirable products, and if the edge should dip slightly below Ms before arresting the cooling action the heat from the spine could autotemper it at too high a range.
On the other hand if the interrupt is too late you will kind of lose the whole point of what you are doing.
Also I personally advise against getting creative with the cooling after the interrupt, it really should be continuous and not too slow, so a simple air cool is just fine.
If you time things correctly you should have a light coating of oil on the blade with some light wisps of vapor coming off.
The blade should not immediately look dry, nor should it flame.
You should not be able to hold it with bare hands but you should be able to hold it for short times with lined leather gloves.
The leather gloves are good for the benefit of most interest to blademakers.
You see since there will be a large percentage of austenite still in the blade, you can sight down it and see if there are any warps starting and if there are any all you have to do is easily push it straight with you gloved hands.
How do you folks think I keep rapier blades straight ?
So if you do things correctly you can have a fully hardened blade, that has already automatically been through a snap temper (you could see perhaps 2 HRC points less as hardened, but that is not lost hardness it is autotempering effects), as nice and straight as you want to keep it, and with a significant gain in some impact toughness due to the low stress method of forming the martensite.
Be it from an interrupt, of from marquenching in salts, every blade I make is done this way so I must admit to being rather biased toward these techniques, but they have worked wonderfully for me for many years.
Pictures of my example:
