Sword HT Question

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Hi All, I am almost finished with my shamshir (28.5" blade, 01 steel), and will be sending it in for Heat Treatment soon. I am uncertain whether to ask for a Rc hardness of 60 or something a bit lower, perhaps 55, as I am concerned about chipping. Any advice would be appreciated.
 

Stacy E. Apelt - Bladesmith

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In O-1, the edge chipping at Rc60 would probably not be a problem.

The concern in a sword is lateral stability - AKA breaking the blade in half with a sideways or misplaced blow. Watch Doug M. on FIF make some cuts and you will se what a misplaced blow can do to a sword ( personally, I think he is a clown).

At higher hardness, the blade will break sooner than one tempered down lower, which also increases toughness.

I do swords mainly in the mid to upper Rc50's depending on the blade type, steel, and expected use. They will all cut well at Rc56. The difference will be in how long the edge holds up in use. If the sword will only get a few demonstration cuts, and won't be chopping up Zombies daily, I would go on the safe side at Rc 56-58. IF you want it to cut tatami repeatedly at competitions and demos, go Rc 58-60.
 
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In O-1, the edge chipping at Rc60 would probably not be a problem.

The concern in a sword is lateral stability - AKA breaking the blade in half with a sideways or misplaced blow. Watch Doug M. on FIF make some cuts and you will se what a misplaced blow can do to a sword ( personally, I think he is a clown).

At higher hardness, the blade will break sooner than one tempered down lower, which also increases toughness.

I do swords mainly in the mid to upper Rc50's depending on the blade type, steel, and expected use. They will all cut well at Rc56. The difference will be in how long the edge holds up in use. If the sword will only get a few demonstration cuts, and won't be chopping up Zombies daily, I would go on the safe side at Rc 56-58. IF you want it to cut tatami repeatedly at competitions and demos, go Rc 58-60.

Thanks, Stacy. This is actually the first full length sword I've made, so wasn't sure. I appreciate the explanation and advice.
 
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The concern in a sword is lateral stability - AKA breaking the blade in half with a sideways or misplaced blow. Watch Doug M. on FIF make some cuts and you will se what a misplaced blow can do to a sword

Another great example of the lateral stresses that a sword undergoes can be seen in a recent video by Skallagrim. He was doing some relatively abusive testing of an Albion Berserker sword and there are many great slo-mo shots of the sword flexing during & after cuts. I believe Albion uses 6150 steel.

The whole vid is worth watching, but you can see some serious flexing at around the 1:00 minute mark:

[video=youtube;epm4hy_zxQQ]https://www.youtube.com/watch?v=epm4hy_zxQQ[/video]
 
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Yes, it certainly does flex a lot, but it must be pretty soft for him to straighten it like that. I was surprised.
 
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Interestingly, the sword I'm working on is also 28 " and made with O1 which I have yet to heat treat. I'll probably aim for a lower RC (around 55) just to be safe.

Stacy, this has been discussed to death but suppose a full austempering were done in this case to RC 60 (or any other hardness above 55 for that matter). Any ideas on how its performance would compare with non austempered at the same hardness?
 

Willie71

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Flex is more related to geometry and thickness than hardness. The effect RC hardness has is the point at which the blade will take a set (soft) compared to break (hard). The amount of force to bend doesn't change, just the set and break points. You want to hit the middle for each steel. For smaller blades in O1, Rc61 is the optimal number balancing harness and toughness. You will get more toughness with O1 at lower hardness numbers, but you lose a lot of the benefit from the hardness, more than you gain from the toughness. For a sword, not as important as a knife that is used for a lot of cutting.
 
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Breaking vs. bending can be a big safety issue for swords that will be cut with much. A piece can fly and kill or injure a bystander or even the user...
Willie, your comments about what contributes to flex are of course correct, as is your statement that edge holding matters much more in a knife than a sword.
I think the foremost issue for me, which is now a moot point, is that I'd likely not use O1 for a sword!
Lots of luck to you, David!
 
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Breaking vs. bending can be a big safety issue for swords that will be cut with much. A piece can fly and kill or injure a bystander or even the user...
Willie, your comments about what contributes to flex are of course correct, as is your statement that edge holding matters much more in a knife than a sword.
I think the foremost issue for me, which is now a moot point, is that I'd likely not use O1 for a sword!
Lots of luck to you, David!

After you brought up the steel question I had to go back and check my order, Salem. I got mixed up, turns out the sword is A2 steel.
 

Stacy E. Apelt - Bladesmith

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With A-2, I would austenitize at 1750F and temper at at 500F for Rc 58-59. I would also ask for cryo if it available in sword lengths.
 
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Would cryo of just part of the blade be benefitial (if they can't do full length) or would that introduce any stresses?
 
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Would cryo of just part of the blade be benefitial (if they can't do full length) or would that introduce any stresses?
I certainly would not want just part of the blade cryo'ed, it's either all or nothing. And I believe they can do a blade this length.
 

mitch4ging

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David,
Look forward to seeing this new project, please post pics when you can!
 
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