5160 & Knife Size

[Ragnarok Forge]

Ok,  I am heading down to a local leaf spring shop to buy some of their drops.  I am wondering what thicknesses of materials people like and what the smallest knives you have made out of 5160 are?  I know it tends to be used for larger knives and camp choppers.  My research indicates that it can get up to 63 rockwell but that is not notorious for edge holding properties when compared to higher carbon steels.  

Any experience you have with this steel and what you have used it for would be appreciated.  I am branching out from the 10XX series steels and prefer to approach this new steel with some ideas of the best uses for it.

[Lin Rhea]

Use it for what ever size knife you want. It holds a good edge, in my opinion.

[Ragnarok Forge]

I was reading on Ed McCaffrey's website last night that he recommended using 5160 for a JS test knife.  It also recommended triple quenching.  Triple quenching seems a bit redundant.  Essentially your growing and shrinking the grain to the same size each time.  Does it really help?

[Lin Rhea]

Clay,
      I have to disagree about the growing grain. The grain does not grow unless you raise the temp 100-150 degrees above critical. If you are careful with your heat, you can repeat the quench two or three times and, yes, some feel this is beneficial. The grain may or may not reduce further in subsequent quenches, but it seems to do something to the moleculular structure to toughen the blade. When you think about it, that is what you want in a test blade.

If indeed you raised the temperature enough in the quenching heat/heats to grow the grain, you are just spinning your wheels. That is why control is so very important.

I think of it like this: There are 3 ranges in which you work the steel.

1-Welding heat, which grows grain,

2-forging heat, which grows grain,

3-and heat treat temps, which should not grow the grain.

Thermocycle between 2 and 3 to bring the grain size down and prepare it for hardening. There are other steps that can be done, of course. Speroidizing, annealing, etc. but these 3 basic temperature phases have to be understood to know how to control it.

[Ragnarok Forge]

Lin, that clears it up. Thanks, I appreciate your willingness to help.  I am shopping for a pyrometer and ceramic sheath for it right now.  I don't think I am getting enough control using magnets and color as heat measuring tools.  I am becoming  more and more convinced that I need to invest in a kiln to get perfect control over the heat treating process.

[jaymoon]

If you are looking for a kiln check out sugar creek kilns out of Indy. About half the price of paragon or even heat. Moon.

[kbaknife]

Originally posted by Lin Rhea:
Use it for what ever size knife you want. It holds a good edge, in my opinion.

You betcha!
I second that opinion.

[kbaknife]

And it's not heat alone that can increase grain size.
That heat also requires TIME!
The correct phrase is "time AT temperature".
You can get steel to the point that many will agree is too hot, but if not held AT that temp for very long, nothing really happens.
5160 performs the best when it can be austenized at around 1525 and held there for, say, 8-10 minutes.
If you have a heat treating oven you can really make 5160 dance!