Annealing O1

[Stophel]

I've been doing this a while now, and I've built a lot of locks, mostly using Siler parts. And I have to say that I still have not come up with an effective way to anneal that cursed O1 steel that they make their tumblers and sears out of. I can heat it and let it cool, I can heat it and bury it so it cools slowly, I can do it over and over and over again, it doesn't matter. It is still D__N hard to drill. Hard spots, squealing, dulling drill bits. Every now and then I can somehow manage to get it soft enough to drill ok... but not usually. It's a PITA.

There has to be a reliable way to do it. Any advice?

 

[Zonie]

I found this on the web.

Based on the information, it seems you are cooling the O1 off too fast. You really need a controlled atmosphere furnace with precision controls to do it right.

"THERMAL CYCLING: In order to avoid decarburization, this grade should be annealed and/or
hardened in a controlled neutral atmosphere, vacuum, or neutral salt furnace.
1. Anneal: Heat slowly to 1450° F, soak thoroughly. Cool 25° F per hour to 900° F. Air cool to room
temperature. Approximate annealed hardness, 221 Maximum Brinell.
2. Stress Relief of Unhardened Material: Heat slowly to 1250° F. Soak for two hours per inch of
thickness at heat. Slow cool (furnace cool if possible) to room temperature.
3. Hardening:
a. Preheat: Heat to 1200° F, and hold at this temperature until thoroughly soaked.
b. Hardening: Heat to 1475 to 1500° F. Soak at heat for 30 minutes per inch of
thickness.
c. Quench: Oil quench to 150 to 200° F. Temper immediately.
d. Temper: Normally oil hardening steels need to be single tempered only. However,
double tempering may sometimes be preferred. Soak at heat for 2 hours
per inch of thickness for each temper. Air cool to room temperature
between tempers. The normal tempering range for this grade is 300 to
450° F.
Temper° F Rockwell "C" Temper° F Rockwell "C"P
As-quenched 64/65 700 53
350 62/63 800 50
400 62 900 47
500 60 1000 44
600 57 1100 39"
http://www.buffaloprecision.com/data_sheets/DSO1TSbpp.pdf

I just noticed. Cooling O1 from 1450 degrees F to 900 degrees F at 25 degrees per hour says after 22 hours after you've cut off the heat, you can let it air cool the rest of the way down to room temperature. :rotf:

 

[Stophel]

Well, that's not gonna happen. I have no way to keep it THAT hot for THAT long.

:idunno:

I truly despise the stuff. I dearly wish they would make Siler tumblers and sears out of something, ANYTHING else.

 

[Stophel]

I wonder if I crank the oven up all the way and bake it for a few hours, would it "temper" it sufficiently all the way through for me to drill the holes...

Not that I have the patience to wait for this stinkin' stuff to bake for a few hours... then cool down.

I gotta find a different tumbler and sear that I can use... Others use different steels that I can work with, but their designs ain't that great. Oh well, I ain't gonna be doing too many more anyway. I'm "retiring".

 

[jerrywh]

I have been working carbon tools steels for 50 years. I never have any trouble with it now. I did at first though. What zonie says is the perfect way to do it but most of us do not have the equipment to do that. I do now but for years I annealed 01 by putting it in a tin can packed with either charcoal or kitty litter. I put it in the wood stove or built a good hot wood fire over it an just let it burn out. When the fire is down to room temp you are ready to go. It will be nice and soft. But-- when drilling tool steel do not let the bit spin because it will work harden the surface. Keep the drill sharp at a slow rpm and keep the pressure on with a little cutting oil not lubricating oil but cutting oil.

 

[LRB]

Chris you are dealing with a hypereutectic steel. The common annealing process does not work well when the carbon content is above .77% to .80%. Using a common anneal allows the carbon to form hard laminate plate like structures in the steel matrix which resists drilling and cutting. If you have the means, soak at 1200°F to 1250° for an hour or so. then let air cool. This will allow the carbon to form into spheres which allow cutting tools to slip by the carbon and cut much more easily. Industry uses a more involved process, but is basically the same. If you don't have a HT oven, you can heat with a torch to a very dull low barely red in dim light then air cool a few times, and usually that is enough to get you by. Keep the heat below non-magnetic,1414°, and that should solve your problem. Do it maybe half a dozen times, or at least three, but don't take it over the non-magnetic level, or you lose the effect because the carbon will dissolve instead of forming spheres, and begin forming plates when it cools. This also works with 1095 steel. This is called a spheroidized anneal, and is the softest condition of hypereutectoid carbon steels, which is how precision ground 01 bar stock comes. When done correctly, you can carve slivers off the edges with a knife. Very soft.

 

[Birddog6]

I use solid carbide drill bits when I have to drill something hard like that.
I drill D2 & ATS34 all the time with them. I think it would drill a tumbler as well.

Keith Lisle

 

[stink koat]

I've been building Siler kits since 1972, with home
shop tools (Sears drill press)never had a problem drilling or tapping. Just finished my 15th rifle w/siler kit...all went well. I only use american made drills /taps.

 

[ZUG]

I feel your pain and frustration. I've built about 28+ Siler kits and had 3 or 4 tumblers that exibited the condition you mention. Two I threw away out of aggravation but the other two I did two heat treatments to anneal the tumblers whiched worked. First I got a large bag of Perlite (cheaper than Vermiculite) from the local garden center then built a wooden box 12" X 12" X 24" with a lid. I filled the box with the Perlite and placed 3 1084 "as rolled" steel bars into my gas forge got the red hot then placed them into the box with the perlite to heat the perlite up. I then lowered the heat in the forge and placed the tumblers in along with my 3 bars of "as rolled" 1084 steel as I also wanted to anneal them along with the tumblers. I waited about 15+ min and placed the tumblers and 1084 steel bars into the box of Perlite & put the top on. I left it for about 6 hours. After 6 hours I fired up the forge and placed the tumblers and 1084 steel back into the forge until the were low red color held it there for about 15+ min then back into the box of Perlite for about 24 hours. After this treatment I could drill the tumblers and cut 1084 steel with ease. A lot of effort but I "kicked it's butt" :grin: .

 

[Stophel]

I have ALWAYS had this problem with Siler parts. You think it's soft enough, you can file the outside easily, and your drill will even start drilling, but go in just a little bit and it starts squealing. O1 seems to harden all the way through quite easily, but does NOT want to temper all the way through. All I have ever been able to do with it is temper, temper, temper, temper (since obviously I have not been able to "anneal" it... :haha: ). Doing that and changing drill bits after it dulls them, and lots of cussing, and I have always managed to get through.... eventually.

Before I made the post last night, I had managed to drill the hole for the screw through the sear. Next up is the tumbler. Not only do I have to drill and tap for the screw, but I also have to drill that tiny hole for the fly. So, while cooking a pizza for myself in the oven, I thought I might as well put the parts in and bake 'em for an hour or two since the oven is on and hot already. I got it at 500 (the hottest it will go) and put the tumbler on some foil on top of the pizza pan. Since I cannot anneal it dead soft, MAYBE I can temper it down enough all the way through to where I can drill and tap it. Wish me luck.

 

[Zonie]

As Jerry mentioned, don't let a drill dwell when drilling O1 (or any tool steel).

It will instantly work harden unless the bit is constantly removing material and when it does, it will become as hard as the drill bit (unless a tungsten carbide bit is being used).

 

[Stophel]

I guess that's what it's doing, then.

 

[Stophel]

So, I'll get me some cutting oil in the morning.. assuming they will have any at the hardware store or auto parts in town.

I am becoming more of a fan of the idea of using the oven to temper with! No risk of over-tempering! At the highest setting, it turns my parts just BARELY past bright deep blue (ALMOST to the light blue stage, but not fully), and no more. According to the charts, this is round about 600 degrees.

 

[ZUG]

Good luck -- also don't run your drill too fast - the point/cutting edge will generate a lot of heat if it's run too fast and spot harden where the point /cutting flutes meet the metal that's why your drill only goes in a small amount then stops cutting and does a lot of "pig squeeling" :wink: .

 

[Stophel]

I keep my drill press on the lowest speed possible. I can't drill any slower! :grin:

I don't have any bits that small for my brace, or I'd cut 'em by hand!

 

[Rifleman1776]

hypereutectic

:shocked2: This is a family friendly site. You aren't allowed to use words like that here. :nono:
:wink: Really. I wonder of gun builders of olde had conversations like this.
Seriously, the way I solve problems like that......I send a check to L&R. :wink: :surrender:

 

[Billnpatti]

I just love those words like hypereutectic, hypereutectoid and spheroidized. I love them. They fairly roll off the tongue. I just know Shakespeare would have used them if he had known about them. I've got to find a way to work them into one of my conversations. :thumbsup:

 

[LRB]

HypEReutectic is the term for steel carbon content of MORE than .77%
HypOeutectic is the term for having LESS.
.77% carbon is the limit of carbon content that can be absorbed into iron into a homogenous solution. Any excess over .77% become free carbides distributed throughout the steel. These extra carbides are what gives extra wear resistance to the steels in the hypereutectic range. Heat treating hypereutectic steels requires slightly different approaches than with hypoeutectic steels. Especially in the annealing of them. At non-magnetic,1414°F, most of the carbon will begin to dissolve into the iron forming a homogenous condition. If slowly cooled at this point, the carbon and iron will separate into a tough layered structure of iron and carbon platelets. If taken to a lower temp for annealing, below non-magnetic, soaked at that temp for a little while, and then slowly cooled, the carbon balls up into spherical shapes within the iron matrix that will allow cutting edges to pass by more freely. Hypoeutectic steels in the upper ranges of carbon content approaching the eutectic point can also benefit, but usually not enough to be worth any extra effort. When drilling hypereutectic steels that are annealed in the common manner, your bit is having to cut through relatively thick platelets of pretty solid hard carbon. Even if your bit cuts through, it will be short lived from the process.

 

[Stophel]

Seriously, the way I solve problems like that......I send a check to L&R. :wink: :surrender:

L&R, nor anyone else, makes a lock of any kind that I find really suitable as-is. In function or appearance. :wink:

 

[Stophel]

I wonder of gun builders of olde had conversations like this.

No, but they didn't have O1 to have to fool with! :blah:

Seriously, I'd be quite happy with tumblers and sears made of iron/mild steel where they could be case hardened and done. No fuss, no muss. I'd also like to be able to properly charcoal case harden, but I lack the facilities to do so. I have made a tumbler and sear out of mild steel and case hardened them with Kasenit, and they work fine, but I am TOLD that Kasenit won't soak deep enough to make a very deep case, unless held at heat for at least an hour or two. Whether that is really true or not, I don't know. On these parts, I think I managed to hold out for about 20 or 30 minutes, holding them at heat, and that was all I could stand before quenching.