Thread: RSO # 1

No worries. O1 -> identify the color at which it becomes non magnetic.
Heat to a bit brighter than that color and stick in ashes or vermiculite -> annealed.
Heat to a bit brighter than that color and dunk in pre heated oil -> hardened.

that's about all there is to it.
Although if you made larger things like a kitchen knife, you may want to normalize before hardening to avoid warp
Heat to a bit brighter than that color and let it air cool until all color is gone. Do this 2 or 3 time and you should be ok.

Originally Posted by Bruno

Heat to a bit brighter than that color and dunk in pre heated oil -> hardened.

I am under the impression that 01 benefits by a 10 minute soak at austenitizing temperature before quenching.

Originally Posted by bluesman7

I am under the impression that 01 benefits by a 10 minute soak at austenitizing temperature before quenching.

Yes and no. Yes, a short soak is good. However, generally, when you are heat treating a razor, the edge is fairly thin compared to the rest. The edge will be at critical some time before the spine and tang are at the correct temperature all the way through. So by the time the entire razor is at the critical temperature, the edge has had several minutes of soak just by virtue of being a lot thinner.

It also depends on how you heat. If you heat directly in the fire, everything will be hot quickly.
If you heat inside an iron pipe in the fire, heating will be slower, causing the spine to need quite some more time than the edge.

The fact is, it's the edge that is the main concern. A spine need not be perfect anything if you use tape :<0)

Originally Posted by Bruno

Yes and no. Yes, a short soak is good. However, generally, when you are heat treating a razor, the edge is fairly thin compared to the rest. The edge will be at critical some time before the spine and tang are at the correct temperature all the way through. So by the time the entire razor is at the critical temperature, the edge has had several minutes of soak just by virtue of being a lot thinner.

It also depends on how you heat. If you heat directly in the fire, everything will be hot quickly.
If you heat inside an iron pipe in the fire, heating will be slower, causing the spine to need quite some more time than the edge.

Thanks for the expanded discussion. I've been heating in a pipe in a gas forge. It makes sense to me to start the soak time when the edge is at austenitizing temp and not worry about the spine. So far all of my heat treating has been very successful. I've only worked with 01 to this point.

Originally Posted by bluesman7

Thanks for the expanded discussion. I've been heating in a pipe in a gas forge. It makes sense to me to start the soak time when the edge is at austenitizing temp and not worry about the spine. So far all of my heat treating has been very successful. I've only worked with 01 to this point.

Yep, same for me iwth 01. I as soon as the blade gets to temp/color, I start my "clock". I soak for about 5 min and quench in warm veg oil.

Originally Posted by bluesman7

I am under the impression that 01 benefits by a 10 minute soak at austenitizing temperature before quenching.

If you have very good temperature controls a ten minute soak will not do any damage. If your temperature controls are, um, looser then you'd like a few minutes, five would be better and ten maybe too long. I'm using salt baths so I'm spoilt by my equipment. A five minute austenitizing soak is what I think is the minimum to ensure all the carbon goes into solution. All that means that the heat is set for the correct solution temperature for the steel being heat treated. This does not include any preheat cycles or ramping steps required.

And so, "It depends."

By good control, I mean a stable holding temperature with adequate thermal mass that adding a cold/cooler than forge temperature object you don't suck the temps down and have to wait for the heat to settle back to the set point.

By looser controls, I think of a charcoal or coal fire where there are part of the heat that are hotter or less hot. The pipe trick really smooths out a lot of those problems but still lets you use natural fuels. LP fires almost need some sort of means to test temperatures, then adjust the air/gas mix until a stable heat/temp can be predictably controlled. The wrong mix even for holding temperature may mean the risk of excess scale formation too. Loose controls on LP fires usually mean catching the right temperature as the heat either rises up through the correct temperature or falls down through that temperature. That's where you might not have a few minutes at the right temperature. A fast rising heat can push the blade up into the coarsening temperatures and you lose any hope of grain control.

Always: learn the heat you have. It means making a lot more blades than you thought to find out what you want to really know. I hope this example makes sense anyway.

Makes a lot of sense to me. More control is better :<0) I have yet to buy the pipe but I do have a nice temp gauge for my LP forge. I have decided to go for the heat treat on this RSO in the forge. Hopefully the RSO actually turns into a razor. Of course there is the last step of tempering if the RSO doesn't warp or crack beyond hope.

Normalize it first, and if you oil quench the chances of cracking and warping are small.
The pipe can be anything as long as it is reasonably thick walled, and not galvanized. I use a piece of 2.25" piping for hot water that I hammered flat.

What Bruno said. In the US pipe like that is still referred to by many as "black iron" plumbing pipe even though today is is no longer made from cast iron.