What should I do?

R

running bird

Joined
Sep 29, 2015
Messages
498
So I have been making a few knives out of some Japanese files I bought from several different garage sales for the past month with 0 problems, and I just finished my third one. But sadly I didn't notice until the knife was complete that it has a very very small fracture on the blade.

The blade is about 5" long, .75" wide and a bit under 1/8" thick and it is a simple drop point shape

The crack is located right smack in the center of the belly of the edge, and runs from the edge going twords the spine. The crack dose not reach the spine it only goes about 1/4 of the way in. the blade is .75" wide, so it is a rather small crack.

The crack must have happend during quenching. Like I said before I made several of these and I wanted to see how this steel would work in a normal water quench ( meaning no salt added to make a brine, just plain water). Obviously I know now that this steel shouldn't be quenched is plain water anymore, I just had to test it out. I didn't notice the crack until I was done so I assumed it worked out great at first.

I'm not really sure what to do

The knife is for myself and I don't really like wasting something that could be put to use, I want to know if anyone thinks it would be unsafe to continue using the knife? Should I just get over it and use it for light work and keep an eye on the crack? Or should I not use it at all and just hold onto it as a lesson to check over a blade several times before putting a finished knife together?

Any advice on what to do with the blade would be great

Thanks for any help,
Kevin
 
Kevin,
Personally I would not trust the knife as the blade has been compromised. There might come a time when you don't think about the crack and push it a little. Is it worth a injury? Making knives is a learning process. Just chalk it up to that.

Ron
 
That's probably smarter than trying to mess with it, thanks

I guess it will just sit in a display case to keep it from causing any trouble
 
I wonder if you could simply shorten the blade a little? Anneal it, grind back past the crack, then re-heat and quench. The blade would be shorter, but you could take it through the process again, and know you have a sound piece.
 
To be honest, use the knife as a destruction test. Break off the part that is in forward of the crack intentionally.
Test the remainder;
See how it holds an edge, bend it, tweek it, hit it against some concrete see if it chips out or rolls, sharpen it back up, put it through the worst you can think of and try to break it.

See what your knives are capable of and use that as an education and fine tune your HT to fit your preferences and to get the most from your steel.

It is a mystery steel, so you should do some experimentation with it to see how you can get a better finished product.
 
If I had it I would just use it till it broke but only at home not somewhere where I need it to be reliable


Sent from my iPhone using Tapatalk
 
Can we see the knife? You can upload photos to a site like photobucket and link them here. Hard to propose fix options without seeing the knife.
 
I wouldn't suggest a fix, since there may be more cracks, or crack prone areas that aren't visable.

Do the safe thing and either hang it on the wall as a "lesson in mystery steel", test it til destruction, or toss it.

Your fingers are worth more when attached, plus they work better that way.
 
It will break easily at the crack, much like when you scratch a piece of glass and it breaks easily at the scratch.

In college I did fatigue tests on large steel bolts, up to 2" diameter. They would develop fatigue cracks in the threads, about halfway around one side of the bolt. When the cracks reached over halfway through the bolt I would stop the test. The samples were a couple of feet long, I could clamp one end in a bench vise, slide a piece of pipe a couple of feet long over the other end of the bolt and break the bolt by pulling on the pipe with my hands. Remember this is a 2" diameter steel bolt, but the crack allowed it to fracture at very low stress.
 
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