O1 Tests -ideas?

Graymaker wrote: "also when they do the bend test it's done
on a big blade plus the
vice jaws are padded with wood so you don't get a sharp
corner at the jaw.
the ABS tests are in place so everyone knows
you know how to manipulate steel once you've past the test."

This depends on the master smith administering the test. I did all my practice tests this way, but when I did the real thing in Wayne Goddard's shop, he would not let me use the wood. His vise jaws were very slightly radiused and he said that's all that mattered. Very sharp jaws can cause a blade to fail, but even a 1/8" radius, Wayne said, should be enough. Also, wood, especially the 2x4s used for most tests, makes a 90 degree flex test more like 60 degrees; the wood gives so much that the blade doesn't have to. I was terrified and sure it would snap like a twig. JD Smith looked at me like "I brought you all the way out here and you better not emabarrass me." More terrified. Anyway, the blade passed. I think if wood is used it should be thin and very hard. Better yet, a good vise with slightly radiused jaws. This way the knife must bend to 90, but it can bend over a tiny rounded surface that will not cut into it and cause an otherwise good blade to fail.

Sorry to ramble,
 
Differential heat treating is usually done with the clay on the back of the blade, which keeps the heat on the back in during the quench and doesn't permit the quench medium to cool the steel down quick enough for it to harden much. When i use clay, I leave the edge free of clay, and a good thick layer on the back of the blade.

Differential tempering is when clay is put on the edge of the blade, and then the back of the knife is drawn back to soften the back, and the clay insulate the edge from becoming too hot and making the edge soft. this is from either the 1989 or 1990 big Knives annual.

When i use clay, i use refractory cement and glop it on the back of the blade and let harden, then HT it. I don't put it on the edge at all cuz i use a small MAPP torch and little forge for my HT, and if the edge is covered, the edge doesnt get up to heat quick enough before the back does. With the clay on the back, the back of the blade is also prevented from coming up for the full critical temperature.


O-1 tests. I have done many. Brass rod is always the first test to be done. 2nd test is to hack up some pine 1x2, the stuff they usually ship steel taped to when ordering from supply houses. I do a lot of paper, newsprint, magazine cutting to test the edge. someitmes i will roll up newsprint and slice it as well. For the bend test, i got results from water quenching mostly with an edge quench. I was able to bend to around 90 or better before the edges popped, and then flexed it to vertical, then back the other way 3 or 4 times to make the whole blade pop cuz the backs were so soft from the edge quench. Also, when you snap the blades, look at the grain. On a properly HT'd O-1 blade, the grain should be very fine, almost velvety and difficult to see. The edges were very fine, and the back was slightly larger due to the softer grains.

Water quench seemed to make the blade less springy, prob because i didnt quench enough of the blade. I'm gonna keep playing with water and oil quenched with O-1, with and w/o clay.
 
Taz - your post got me curious. Like you, after edge testing I took an 01 blade I flexed to 90 when the edge snapped. I also moved it around until it broke. Anyway, I just took a look at the break under the highest power on my stereo microscope. The grain from the edge to the quench line is definately finer - almost sandy smooth, where the area above ( the spine) looks pebbly. Also, the quench portion, as looked at in section (edge up) , appears to have very thin layers that start parallel to the side and then curve over, like an upside down "J". Ideas?

Bob
 
Hmmm. I dunno as I have never examined blades under a microscope. Maybe its the steel that quenched first on the outside, then worked it's way in? Or maybe from the tempering process? i honestly have no idea. Lol. Hopefully somone else can answer it better than i can!
 
Also, the quench portion, as looked at in section (edge up) , appears to have very thin layers that start parallel to the side and then curve over, like an upside down "J". Ideas?
Click to expand...

If you are describing what I think you are, you may simply be viewing twisted steel. Remember, that type of bending will create visible stresses in the broken section that give way to a similar effect you describe. Harder steels exibit this less and more for softer. There are other variables, like elongation and yield strengths, but hard and soft are the primary examples. Hope that helps. :cool:

-Jason
 
I talked to Ed caffrey last night. he said the lines are the flow of the grain from when the steel was milled and rolled at the factory. He said the steel moves unevenly underneath the rollers and causes the lines.
 
I would agree..kind of like micro Damascus..

 As far as using clay there are many ways makers do it
 the way I listed it, is the way one
Japanese Master sword maker did it.
  from a biography study on him,
it's the only way I'd do it, if doing it the old way..
 
Taz & Dan - From what I have seen of films & books of the steel making process, I would agree with Ed's assessment. The view of the entire section under magnification was really kind of neat - wish I had some way of photographing it.

Bob
 
For clay tempering, I'm having good results using Fireplace Mortar. I'm getting mine in the caulk tube and that makes it very easy to apply. The key is to let it dry completely after application. It is best to wait 24 hours or more. If it is not dried out, the heated moisture left in it will cause gas bubbles and screw your hammon line.
Doc
 
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