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WTK- are there any Files members who can try hardening a blade for me? Bought a Wakizashi,turns out blade NOT hardened,wont take an edge.

EinheitElf

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Hey guys ,picked up this supposed vintage wakizashi...ended up not as advertised...long story short-I am already into this too much but no way to unload a knife that cannot be sharpened..sooo I figure there are a couple guys here who DO do some knife smithing and am reaching out for some input and help.
Basically a 16" blade and I think it is some kind of layered steel(thought I saw some fine layers) . There are a couple either japanese or chinese 'mei' characters that I still intend to get translated if possible(that is where I messed up,figured if signed it should be a decent blade..).
I need some input as to whether it COULD be heated and hardened/tempered and at least given a workable edge.

I thank you for any tips,thoughts,suggestions,etc... NEVER have had one like this before....
 

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Andy the Aussie

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The hardest part with this will be not knowing the steel composition so as to be able to work out what heat treat that it will need. Also it may or may not come out of HT straight.

I am however not a knife maker just a user but there are some on here who dabble who may chime in.
 

SWOHFAL

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Better asking this on Blade Forums. Also, you can't just sharpen these like most knives, but they need specialized polishing to maintain the full bevel and that's a skill that takes as long to apprentice as smithing them - and a way many folks ruin these when they are inexperienced. I've heard that $50 or more per inch is not unusual for the charge and there are only a few guys in the US who can do it, West Coast and Hawaii, outside of Japan.
 

RG Coburn

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isn't it with katanas..that its the heat treatment/quenching that gives it its distictive blade curve? My wife unit uses a google feature that allows you to just take a photo of something,and you can search the web for that thing. I'd be interested to know what would come up,especially the characters. It'd suck to get a bazillion hits for a counterfeit blade,but hey...
 

EinheitElf

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Here is one of my legitimate antique Wakizashi, blade made in the mid to later 1600's not sure if the mountings are the same age but they are old, blade has evidence of being mounted to like 3 different handles over the centuries.
 

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Gazz

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Heat treating a blade is fair amount of work. Japanese blades frequently have a hamon which is a distinct temper line in the steel and is created by applying clay in a pattern to the blade before heating to the nonmagnetic state and quenching or hardening. Then the blade must be tempered in an oven or by skillful use of a torch or other heat source. Then the whole blade must be polished to remove the scale from the hardening process. Lots of work. In this case no one knows what the steel is and being a Chinese copy, may not be hardenable in any case. I wonder if the blade was made from some stainless alloy which polishes up nicely but never can hold an edge.
 

aron82

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You could test an area of the tang relatively easily. All you need is a torch, oil for a quench and a file.
Heat up a corner of the tang to a nice chery red, you can check it with a magnet it should go non magnetic at the quenching temp. Dunk it in the oil and let cool completely. It should come out file hard if it is hardendale steel. A file shouldn't bite and just skate off of it.
If the blade is non magnetic as it sits then it's a stainless and probably not hardenable. Japanese katanas were historically about the equivalent of 1050 carbon steel. They coat the blde with varying thickness of clay for the quench. This gives a hard edge and softer- tougher spine.
If it's hardenable steel I might be willing to give it a go at heating and quenching. Would depend on a few things. As others have said it may very well warp when it is quenched. Warps aren't impossible to get out, but can be difficult and take a lot of time.
 

Tuhlmann

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Thanks, I will try your suggestion when I have a chance and get back with the results.

BTW, any special or preferred oil ? Info please.
Consider performing a simple acid etch to see if you have either patterned or laminated steel. Seeing "fine layers" isn't necessarily indicative of a pattern welded blade. It could be alloy banding, which is not uncommon in simple steels as well as some lower end stainless or parastainless steels. An etch will prove that out without damaging your blade. If it is laminated steel, ensure that the blade grind and edge apex on the center/hardenable steel and not the softer cladding. Carbon steels will generally darken in etch, while alloyed and stainless steels will not.

You need a fast oil. Parks 50 is a formulated quench oil that is designed for your task. it's about $50 or so a gallon. Since you are just kind of fussing around, any high quality canola oil (yes, cooking canola oil) is a pretty fast oil and is probably "good enough" for testing the tang for hardness in your case. A best practice would be to submerge any of the blade that you don't want to ruin any possible temper while you heat the tang. Water is fine for this, and will ensure that heat will not compromise the state of the steel as it already is. Heat the tang to nonmagnetic and as quickly as possible dunk in your quench oil while agitating vigorously to avoid any vapor jacketing. Keep in oil until safe to handle.

Skating a file is "good enough" to see if the steel is hardenable, but there is a lot more to a good heat treatment than what you see on Forged in Fire. If it is laminated, it's most likely only the high carbon center will harden, so that is the only steel that you are concerned about. The outer layers are likely a non-hardenable or much lower hardening steel if it was constructed traditionally. A decarb layer may be present on your newly heated tang, so before you file test you must remove that layer of carbon-vacant material. a quick buff to clean steel is necessary for an accurate assessment of hardness. NOTE: Decarb is usually only a few mils thick, but that's more than you think when sanding by hand, and less than you think when running 4,000RPMs on a belt sander.

The other possibility is that you have a junk steel reproduction that was never intended for anything other than display. Good luck, and feel free to reach out with any questions.
 
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tdb59

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^ That reference to Canola oil is interesting.
I found that Cottonseed oil worked beautifully as a quench for knives made of O-1 tool steel.

I have friends that have used ATF successfully as well on 5160.
 

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^ That reference to Canola oil is interesting.
I found that Cottonseed oil worked beautifully as a quench for knives made of O-1 tool steel.

I have friends that have used ATF successfully as well on 5160.
Any oil will “work”, but just like working with scrapyard steel your conditions are unknown and therefore quality cannot be reliably repeatable.

Canola oil (heated to 120F) very closely mimics the P50 curves, which in turn is engineered to closely mimic water, but with reduced rates at the critical points to prevent cracking. What canola oil doesn’t have is the additives that preserve actual quench oils at the high temperatures they are exposed to so the oil oxidizes and polymerizes relatively rapidly, changing cooling characteristics over time.

For the OP’s purposes none of this really matters.
 

aron82

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He's just checking the bottom corner of the tang, most any thin oil will work for quench.
Don't breathe the fumes, some oil additives are not good to breath in. The canola oil would work well as recommended.
Nothing wrong with a file test.
You can spark test the steel to see what color sparks and pattern it throws. But that requires grinding the blade, or tang.
 

gunplumber

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silly question - I vaguely remember from my reading as a teen - back when I had more time to read, that the blade is packed in clay and only the edge is heat treated?

I've done similar in welding bolts, to limit the area of heat transmission, although it was a fancy branded heat stop. I'd be disappointed to discover it being only rebranded clay. I was just following directions without understanding the why.
 

Tuhlmann

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The clay slows the rate of cooling in the quench, resulting in a softer spine than edge. The hardness differential allows for a tougher blade with a forgiving spine and a harder edge. For a monosteel blade, this means increased blade flexibility while preserving edge sharpness and retention characteristics.
 
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