Edge temper burned

I have a few questions/observations about this:

1. Where exactly does this discolored area lie, how hard (or soft) is it, and how does this area compare to the typical hardening of other HI Katana's?
Is it out of spec? Ask other Katana owners about the hardness and sweet spots on their blades. You may find other Katana's are soft in some areas with or without discoloration, and then you are only looking at a cosmetic fix- no big deal.

2. If this is a true flaw/mistake, turn it in.

3. There are many things worth fixing on your own. This isn't one of them if it meets the criteria of substandard.



munk
 
I wouldnt go off and re-heat treat yet. The steel might not respond well to it, and I can personally tell you that there is a heck of a lot more to the clay method than covering it all with satanite and then wiping it off the edge.
 
Svashtar - if you send it to me I'll clean it and test it for you.

Otherwise, do the file test by running an ordinary file down the edge (as if you were steeling it with it) - pay attention to how it feels and sounds as it passes the discolored spot. If it slows down, grabs, digs, lower in sound.....it is indeed a bad temper.

The blue color is surface only. Believe me on this...I do it all the time on annealed steel (prior to heat treat). Comes right off on the next swipe on the grinder. Do what Yvsa suggested , but I would start with 400 grit paper, then 600, 800 and so on.


Do not try to retemper - not worth it. The biggest problem is not the quench, it's the slow-temper. You'd need an oven big enough to fit it. Plus you'd have to take the handle off, etc.

If you're truly disappointed in it - and I completely understand why - ask Uncle to cut you a deal on the next one and send it to me instead of H.I. I'll make something else out of it if you like. We're building a forge here big enough to handle a sword. Would be fun to play around with it.


But, I honestly wouldn't worry about it. Once you sand it off, and rebuff, it'll look good as new, and since no one will depend on it in battle....it'll be alright. Mostly a looker, right?


Unless you're going to chop wood with it...ala Nasty at the MWKK....:eek:
 
Norm, the color that your blade is discolored to indicates that the blade probably got up to 500-550 degrees. If MBZ springs are the same as 5160 then you should still be at 52-55 Rockwell hardness, which is as hard as European swords generally were. Traditional Japanese swords are nearly full hard at the edge, in the neighborhood of 60 Rockwell ~ very hard, but not very tough. The oxidation (which is what the discoloration is) will come off with very fine grit sand paper, as it is only superficial. I would start with 1000 grit, or use car rubbing compound in a fine grit. As far as your edge chipping out, don't worry about it ~ it is less likely to chip now than it was before. Deformation on impact of something hard such as bone, though, is now more likely.

You can not re heattreat just the section that is discolored. Here is the Reader's Digest version of heat treating 1) Hardening ~ Blade is brought up to critical temp (austenitic state) which is 1525- 1550 for this type of steel, then quenched to rapidly cool the steel so as to form martensite. The blade is now very hard, but too brittle for use. 2) Tempering~ Blade is brought up to 350 - 500 degrees (depending on intended use) to slightly reduce the hardness. So, the point is, to heat and then reharden the dicolored portion you would be simultaneously heating (therefore softening) the surrounding areas to a lesser degree. The heat would be above the acceptable tempering range but below the critical hardening range. Clear as mud? ;)

Therefore, if you were to re heattreat it would have to be the whole blade. This is not a minor task, and can result in the edge cracking because it is now finish ground thin (you leave extra meat on the edge before heat treat. With 0-1 tool steel I like to leave about .030-.040").

The best thing to do is check the edge with a smooth sharp file. See if it grabs more in the area of discoloration; if so, push on the edge at an angle with a .25" brass rod and see if it deforms, and stays deformed. If it does it is too soft , call Uncle and he will take care of you.

Hope this helps

Stevo
 
Thanks to all of you for your great advice! I will test the area with a file and see what I can find out, and then take your advice and try and polish the areas out.

Dan, the sword is mostly a looker, although I have chopped some slender bamboo shafts with it with much success, but there was nothing there hard enough to stress the blade very much and it was moving fast.

I have had several khuks with blems or other small problems I know Uncle Bill did not see, but I don't want to get in the habit of sending stuff back just because it's not flawless, and as my background is SQA I know I'm an overly picky bastard anyway. Usually a little work on my own can fix the problem. For sure, if a handle snapped off I would give UB a shout, but most stuff is unintentional, minor and usually fixable.

The worst I had was a movie model by Bura that had just about the most atrocious bolster to handle gap and fit that I have ever seen. Trouble is Movie models are not that common, so I didn't want to send it back. Tried all sorts of things. Finally shoved JB stick putty into all the gaps and started sanding the handle out. Got up to 1500 grit and then buffed with red rouge and it looks 1000% better.

Thanks again to all your advice and information on heat treating and temper. I learned a bunch. I will post some before and after pics if I can.

Regards,

Norm
 
Svashtar said:
...I don't want to get in the habit of sending stuff back just because it's not flawless..... Usually a little work on my own can fix the problem.
Click to expand...
Couldn't agree more, Norm. Consider it an opportunity to experiment with the blade. I had one that got beat up a little bit....made me depressed....until I realized I now had an official "beater"....:D.....and off I went to give it as much heck as I could muster.


Stevo - thanks for saying everything I forgot....:footinmou


:D
 
stevomiller said:
Norm, the color that your blade is discolored to indicates that the blade probably got up to 500-550 degrees. If MBZ springs are the same as 5160 then you should still be at 52-55 Rockwell hardness, which is as hard as European swords generally were. Traditional Japanese swords are nearly full hard at the edge, in the neighborhood of 60 Rockwell ~ very hard, but not very tough. The oxidation (which is what the discoloration is) will come off with very fine grit sand paper, as it is only superficial. I would start with 1000 grit, or use car rubbing compound in a fine grit. As far as your edge chipping out, don't worry about it ~ it is less likely to chip now than it was before. Deformation on impact of something hard such as bone, though, is now more likely.

Stevo
Click to expand...

Basically what I w said at the beginning of the rant. :-)
 
hawkwind said:
Basically what I w said at the beginning of the rant. :-)
Click to expand...

No, you are absolutely right Hawkwind; on the hardness and the problem and the cure. (Although I will assume you meant to say "thread" instead of "rant." :) ) You just kinda got talked over by folks building at length on your initial comments.

Thanks very much for your expert advice. I'm glad you were able to ID the problem so quickly. For some reason I thought "burn" equaled "super brittle", you know kind of like when fire has burned wood, and was mostly afraid of the small blue section chipping out in time.

I'll let you all know how it goes.

Regards,

Norm
 
DOH! Wasn't trying to steal your thunder Hawkwind! :footinmou How about if we just say great minds think alike? Hah, but I did point out the mechanics of WHY you couldn't re-harden a single portion of the edge. Take that :D Just playing!

Norm, there is a time when you can "burn" the steel and it will then be brittle, but it is at a temperature that is WAAAAAY higher than your blade saw during polishing.Burning happens at a temperature above the forge welding temp, and there is uncontrolled grain growth (amongst other nasty) things going on. This will indeed make for a weak and brittle blade.
 
Folks, I m no native english speaker. Sometimes I use word which might be not apropriate like rant, instead of thread. It just happens.

:rolleyes:
 
hawkwind said:
Folks, I m no native english speaker. Sometimes I use word which might be not apropriate like rant, instead of thread. It just happens.

:rolleyes:
Click to expand...

Hawkwind, what part of the world are you from? What nationality? Believe me, I can guarantee that your English is better than my skill with your native language, whatever it is!

Anyway, welcome to the Cantina!

Regards,

Norm


P.S. Hawkwind, just did what I should have done first and checked out your past msgs. I see you are from the Czech Republic and posted your first message on 10/26, so I should have welcomed you then to our khuk asylum!

I have a very close and brilliant friend who is from Ljubljana, Slovenia, approx. 500 KM south of you just north of the Adriatic. He is a very gifted software engineer, and speaks several languages. I hope someday to get to that part of the world and see it for myself. Are you near Prague?

Thanks and regards,

Norm
 
I m about 30 minutes from Prag by car. :)
I learned most of my english by reading of books, I didnt took any classes, so I make a mistake time from time.

If you ll come by, I ll be gladly your guide through Prag. :)
 
hawkwind said:
I m no native english speaker. Sometimes I use word which might be not apropriate ....
Click to expand...
Sometimes I do too---several times daily;
& I've never spoken any other language. :rolleyes:

I'm much better expressed in writing because of this,

Any case, belated 'welcome',
come often,
put your feet up,
cup of tea?

~
~~~~~~~~~~~~~~
<>call me 'Dean' :)-FYI-FWIW-IIRC-JMO-M2C-YMMV-TIA-YW-GL-HH-HBD-IBSCUTWS-TWotBGUaDUaDUaD
<> Tips <> Baha'i Prayers Links --A--T--H--D
 
Hawkwind, forgive my poor manners. Welcome to the Cantina! My sister just returned from Prague this Wednesday, she loves your country!

stevo
 
Oh guys I m blushing. :)
How it is that the people with best maners and most friendly ones are to be found amongst former army men, weapon collectors, shooters, hunters, snipers etc.
This phenomena is observable on large scale in internet discussions (and in normal life off course).
The reversable to this the so called "inteligentsia" is most arogant of any kind.
Might be a good thema for sociological research.
 
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