Is this normal for AUS 8a ss?

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whitefox

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Mar 3, 2011
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I order my self a Ka-bar TDI Law Enforcement Ankle Knife not to long ago.
1486_large.jpg

Yes the one in this photo.

When I examined the knife I notice it had a few dull area's, or where the very edge, flatten ever so slightly.
It was still sharp and could somewhat cut hair off of my arm. That night I begin to work on the edge, and put a convex edge on it.
Max grit I went up to was a 600, then stropped it on some leather loaded with green compound. The edge came out very sharp and was able to cut hair a lot better then the factor edge.

The next day I would play with it in a way. I would pull it out here and there, not really cut with it, but just pull it out of it's kydex sheath.
Eventually I examined the edge and I notice the edge yet again had some minor area's where the edge flatten a bit or started to go dull.
However I did no cutting. I assumed this was from the knife cutting the inside of the kydex sheath every time I would pull it out, even slowly...

So I stropped it again, and brought the edge back. I decide to do a little bit of cutting. I cut up several slices of 1 banana, and the edge was fine. I then moved on to a orange. Cut it up, then carved the skin away from the orange.

I examined the edge again, and once again it had area's where the edge begin to go ever slight dull. When I mean dull, I mean, I could see the edge flatten out in some area's. I would see a bright silver line on the edge where it appear to be going dull.

Is this normal for this steel? AUS 8a ss.
I thought maybe it was heat treatment on the knife, then again I hear a lot this knife is consider a "last ditch knife". Not sure if that has "certain meanings"....

What are some ways I could test it to see if this heat treating issue and not just the steel it's self?
 
You can start by doing a edge flex test, this will show if you have a problem with the steel or edge thickness. A bic lighter works, place the edge at the relative sharpening angle then roll up onto the apex by lifting the spine. Applying pressure from the lighter the apex of the edge will either deformed or do nothing, nothing is what you want.

Most often when a edge is convexed the sharpener has taken the advice to keep the spine low and use light pressure. This practice makes for a sharp but weak edge and possibly your problem.

Some sheaths have been known to dull edges too so that's still a possibility.
 
Well I tried out what you said, and the edge didn't do anything until I applied a lot of heavy pressure then I could see where the edge rolled over ever so slightly.

I then went and drawled the knife fast 5 times, and examined the edge, and saw a few very tiny area's where the edge dulled.
 
Sounds like the steel is a bit soft .That steel performs well when HT'd well !! It will certainly easily cut kydex.
 
HT'd?

I also happen to find this, and this is with the EsKabar and that steel is 1095 cro van!.
[video=youtube;rdP8Y0z-Yp4]http://www.youtube.com/watch?v=rdP8Y0z-Yp4[/video]
 
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Well I just order a Kabar TDI Law Enforcement knife. The smaller version.
ka1480.jpg


I will report back about my findings with the steel of this knife since it has the same steel as the Ankle Knife.
I will put a convex edge on it just like what I did with the Ankle Knife, and see if the steel begins to go dull after a few pulls out of the sheath. Thanks to those that responded to my question.

EDIT: I also wanted to add that I did some push cutting with the TDI Ankle Knife, and I didn't see any edge dulling after cutting through small wooden dowels and weed whacker string.
 
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It's not the edge or the steel or the heat treat. It's the sheath making them dull. I am not sure if that is actually kydex. The BK11 & BK14 are NOT kydex. If there is any type of fiber/glass in there, it will dull a razor sharp edge.
 
Thanks TwinStick. I just now ran the knife several times over the outside of sheath for the Ankle Knife, and I spotted a lot of dull spots, or really bright silver lines on the edge.
 
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Replacing the sheath is an option, as is adding a micro-bevel to your edge in order to increase durability. It's far from a barn-burner, but properly done AUS-8A is a much more capable steel than many give it credit for.
 
TwinStick said:
It's not the edge or the steel or the heat treat. It's the sheath making them dull. I am not sure if that is actually kydex. The BK11 & BK14 are NOT kydex. If there is any type of fiber/glass in there, it will dull a razor sharp edge.
Click to expand...

I agree with TwinStick. I think that the fiberglass reinforced sheath is the culprit. It would make the most sense as glass is a very tough substance and could be taking that micro fine edge off. I have several pocket knives in Aus 8 and they have no problems and a couple fixed blades with leather sheaths that have no problem. It is usually the glass reinforced sheaths that I have problems with and that is with any steel.
 
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