differential hardening?

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pso

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Oct 29, 1998
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I am working towards making my first knife, a kitchen knife. I have read through the posts on this forum and the archives. I will most likely use O-1 or 5160 to make a small (5" - 6") kitchen knife. In this application, should the blade be differentially hardened (either by quenching only the edge or by drawing the back after quenching the whole blade) or should the whole blade have the same hardness. Thanks in advance for your assistance.

Phil
 
I really don't think you'd gain a whole lot functionally by doing a differential heat-treat, but it would certainly look cool to have a temper line on your kitchen knife.

If you sand the blade to 2500 grit, etch in ferric cloride, and then rub the blade out with Flitz polish for about 20 minutes, you will have a beautiful blade that will be better suited for corrosion resistance as well.

I would recommend 1084, 1095, or 52100. Either 01 or 5160 are great steels, but I think you'll have a little easier time with the 1084 or 1095 (vs. the O1) and you'll have better edge retention with the 52100 over all of them.

Just some ideas. Email me if I can help more :)

Nick
 
For your first knife use the 5160. It is more forgiving than during the forging, heat treat and tempering than 52100 and I believe that it will hold a better edge than 1084 or 1095.

Bill Burke
 
Hello Nick and Bill

Thanks for the advice. I was going to go with the O-1 or 5160 because that is what I can get easily here in small-town New Zealand. The shipping from the places like Admiral in the U.S. would probably cost two or three times the cost of the small amount of steel that I would be buying.

Phil
 
In that case I believe I'd go with the 0-1 for a kitchen knife and do an edge quench for half the width of the blade followed by a normal temper cycle at 400 deg. F. Just heat the edge for the quench and no spine draw will be necessary as it will never get a chance to harden much aside from a little air hardening. But the key words here are 'kitchen knife'. It would be a different story for a heavier blade.

I normally take the steel to a 360 grit finish and then etch in ferric chloride to highlight the quench line. Then finish with 1,000 grit and follow with 2,000 grit for a final polish. #0000 steel wool is good for a final finish as well. Good luck and post a pic of your finished knife if you love us :)
 
Thanks for the suggestions, Max. I am tending towards the O-1 as the prime candidate since the tool and die maker we have at work uses it quite a bit and would be better able to help me. I think the wife would be quite ticked to be using a knife with a temper line. Got to keep her happy...;)

Of course I love this place and all it's contributors. That's partly why I am trying this out. Beeing the geek that I am, I'll figure out a way to post some pictures. I know I like seeing what other newbies are up to.

Phil
 
I was interested to read that at least one poster felt that 5160 would take/hold a better edge than 1095 and 1084. I am not arguing here but would like to hear some explanations for this. Since many of the ABS master smiths have been moving from 5160 to 1084, I sort of assumed the opposite might be true. Any information would be appreciated.

John Frankl
 
My opinion is based on my own personal experience. It could be due to the fact that I have done much more testing and expermenting with 5160 than I have with any of the simple carbon steels. The last knife that I made with 5160 will make 200+ cuts on hemp rope. It also could be the chromium and manganese found in 5160 and O1. The chromium will form cromium carbides that are harder than carbides found in simple steels and manganese in addition to being a grain refiner also makes steel that is more abrasion resitant than simple carbon steel. Maybee some of the masters will comment as to why they are moving in the direction of 1084 and 1095.


Bill Burke
A.K.A.
 
The heat treating method that Max described sounds like it would leave the back unhardened. Would the finished knife be "soft" or springy? I have a store-bought one where one can bend the blade with finger pressure and it stays. It never springs back. It's almost as if they had a bad day in the heat treating department since all the others are springy and stiff and they are all made from laminated steel.

Thanks again for your help.

Phil
 
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