HI Sword Hardness

Ezaske

Ezaske

Joined
Sep 14, 2010
Messages
62
Does anyone know how HI heat treats their swords specifically the Tarwar. I have a Tarwar and did a citrus etch on it because I was curious about the tempering. I expected to see a hamon along the length of the edge or at least a sizable sweet spot, but the etched blade is a nice uniform grey except for a small 2-3 inch section toward the tip of the blade. I am wondering if the etch failed. I used oranges and kept rubbing them up and down the blade for 45 minutes. This normally darkens the softer metal and leaves the harder sections a lighter color. I will etch the blade again using lemons and see what I get.
 
Great question -- I would think the Tarwar would greatly benefit from being differentially hardened, so I hope that's the case. Maybe someone more knowledgeable will chime in.
 
Ezaske, g,day and welcome. Most blades ,whether kukri or swords, made in Nepal, use 5160 (or close) steel. Used leaf suspension springs from trucks and buses are commonly employed. 5160 is a deep hardening steel, and as such, will not give you an "eye popping" hamon, unlike (say), 1095, which is a shallow hardening steel. If you want to learn more about the arcane science of steels and blades, pop over to the bladesmiths forum. Cheers, Mike.
 
Afaik, H.I. swords are HT'ed in the same manner as the khukuri.
The working edge should be hardened.
As Mikejames stated, you will not have an eye popping hamon. The hardened part will only show as slightly darker than the unhardened steel.
 
I have been able to see the hardened area on a number of khukri I have done a citrus etch on. It was not eye poping, but plainly visible (though difficult to see in pictures). This Tarwar however is being very difficult. The second etch, with lemons, shows a hardened area that runs the whole edge minus 3 inches at the tip and 3 inches at the guard. However the hardened area is very erratic, 1/2 inch in 2 spots and only 1/8 of an inch in others. One section is only 1/16 of an inch wide. I am not sure if I trust what the etch is showing me. The hardened area just seems too thin in most parts. It's also very wavy. Rajkumar did this one and he does very nice work.
 
Just wondering but have you tried taking a punch or something and tapping it along the edge??

A lot of times I can hear the hard parts when I get to them.
 
Ezaske said:
I have been able to see the hardened area on a number of khukri I have done a citrus etch on. It was not eye poping, but plainly visible (though difficult to see in pictures). This Tarwar however is being very difficult. The second etch, with lemons, shows a hardened area that runs the whole edge minus 3 inches at the tip and 3 inches at the guard. However the hardened area is very erratic, 1/2 inch in 2 spots and only 1/8 of an inch in others. One section is only 1/16 of an inch wide. I am not sure if I trust what the etch is showing me. The hardened area just seems too thin in most parts. It's also very wavy. Rajkumar did this one and he does very nice work.
Click to expand...
What you are describing is pretty much the norm. The tip is unhardened, as with khukuri, to prevent the tip from shattering instead of folding. The end toward the guard is left unhardened to preserve the elastic properties that 5160 steel provides.
One must remember that all these blades are differentially HT'ed by eye and hand with tepid water from a teapot. Done in the traditional manner. The hamon line will never be perfectly straight or even in all areas of any blade.

Steve Tall said:
Maybe the heating from the mirror finish polishing interferes with the surface hardness.
Click to expand...
That could be a possibility and i would not say it could'nt happen.

For those that don't understand:
Sometimes during the polishing process, a thin skin of annealed metal will form over the hardened areas. It may sometimes slightly chip out and look like the blade has a bad HT. Once you sharpen it and get to the hardened steel the problem is solved and the blade performs well.
 
The Tarwar is a villager and has never seen a buffing wheel. So its not pollishig annealing. My hope is that the hardened area extends past what I can see with my etching. The etching is too faint to take a picture of, but what I can do is mark the darker areas with a felt tip pen and post a picture of that so everyone can see what I am talkig about. I also want to be clear that I still love the sword and am in no way complaining. I just got a result from etching that was odd and hoped to get some answers here.
 
Well Sir, if you really want to know, then get it rockwell tested in 1/4" pattern over the whole blade, you may want to stone and flatten the bevel on both sides and sharpen before the testing as it adds to the accuracy of the test.
 
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