Really hard 1084

samuraistuart

samuraistuart

Joined
Dec 21, 2006
Messages
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I'm using Aldo's 1084, it has .80% manganese, and this stuff is really really hard! Making 4"-5" hunting knives. I'm quenching in room temp canola oil after a minute or two of even temperature, should be really close to 1500 (but I have no way to judge that other than colour past non magnetic). I'm tempering in kitchen oven at 400 twice for an hour and a half each time, each time quenching in H20. Very nice straw color. I want to draw file a little bit more after heat treat, to bring that edge down from .020" to almost zero, but the file will not bite. It will scratch the bevels, but that's it. I'm not putting much pressure down on the file, but I was hoping that my current method of heat treat would allow me to file the blade down more. I doubt very seriously that I'm going past 1475-1500, because of colour past non magnetic. Maybe a shade or two more than 1414 degrees F. No "bubbles" or "anomolies" that usually indicate too high of a temperature prior to quench....I think my Mark I eyeball is calibrated fairly "accurately".....or is it "precisely"?

Since I'm very new to all of this, I would like to ask your opinion on filing a bit more post heat treat to bring that edge down a bit more. After your heat treat, are you able to draw file your edge down further, or do you resort to your abrasive papers and belts to do this job? Thank you so much!
 
Sounds like your heat treatment is fine. Filing after heat treating is usually not done, or even possible.

Use abrasives to take the edge down after HT.
 
You use a block of hardwood, or a bar of steel with wet-or-dry paper on it. Use it just like a file. Start with 220 grit unless you really need to take down a lot of metal. Once the surface is right and most of the excess metal is off, go up the grits to as high as desired, but at least 400. At the last step you want the edge to be almost sharp. About .005" wide.

Another good way to take down the blade, and get dead flat bevels, is to use a granite surface plate. Spray a little water on the stone and set the paper on it. It will stick by capillary action. Put some water on the paper and sand the blade against it. Change paper as needed.

As said above, after HT you won't be able to file or drill the blade in any normal way.
 
Put an edge on it and see if it is chippy before you put the handles on. Depending on how the quench went you may have to temper at 450 to get it to work.
 
I'm using 1084 for the first time right now, and holy abrasion resistance, Batman! - it does get HARD. It's a whole new game compared to polishing steels like W2, but then again I may not have tempered my current blank long enough. As far as I'm aware, the most a file is used for post-heat treatment is to check the setup of the martensite, to see if it skates smooth rather than leaving deep marks in the steel. I use a segment of stainless flatbar about 1.25" wide to tear off strips of sandpaper and wrap + tape them around it, both to decrease the time put into polishing the blank and to keep crisp profile geometry while I polish. Small segments of wood plank will work also, as others have mentioned before me. A trick to use so that you'll know when you're done with a certain grit is to wet sand at a different angle than what you did for the previous grit - for instance if you start out with, say, 150 grit and you sand parallel to the edge, then once you start 180 grit sand perpendicular to the edge. This will reveal scratches from the previous grit until they have all been buffed out, that way you don't end up getting to 320 or 400 and suddenly marks from a coarser grit begin to show.
 
Ninja Blacksmith said:
I'm using 1084 for the first time right now, and holy abrasion resistance, Batman! - it does get HARD. It's a whole new game compared to polishing steels like W2, but then again I may not have tempered my current blank long enough.
Click to expand...

You must have got a hold of some bad W2. Or roached the heat treat?

The W2 I use gets harder than 1084 and is noticeably more abrasion resistant!
 
I have been draw filing my clips in post HT after reading a WIP that John White did. I'll rough it in with the grinder, but finish it with files. It is hard on them, usually trashes a cheap 6" on a fighter or Bowie. This is in W1 and 1084/15n20 Damascus. Should I not be able to do this? IIRC it was the Old Glory D guard Bowie WIP that I picked that up from. Of course, I'm removing a lot less steal on a clip then the bevels. I have never tried to draw file the bevels post ht.

Just tring to learn, not pick a fight, cause I'll lose!!!
Respectfully
Cody
 
Don Hanson III said:
You must have got a hold of some bad W2. Or roached the heat treat?

The W2 I use gets harder than 1084 and is noticeably more abrasion resistant!
Click to expand...

It could've been poor heat treatment or over-tempering (It was the first hardenable steel I had any experience with, a mix of hits and misses until I learned that it's OK to do interrupted quench, and it took me a while to figure out that for the oven I use, if I want to reach 400 F, then set the dial to 300 F.) I still have some scrap pieces of W2 from the same stock, and could heat treat one and then compare to the 1084, now that I'm a lot better at this trade than I was a year ago.
 
If it was more available in my area, I'd use W2 exclusively for mono steel. There is no issue getting a solid performer out if it, and I find it overall superior to 1084 in my limited experience.
 
Ninja Blacksmith said:
It could've been poor heat treatment or over-tempering (It was the first hardenable steel I had any experience with, a mix of hits and misses until I learned that it's OK to do interrupted quench, and it took me a while to figure out that for the oven I use, if I want to reach 400 F, then set the dial to 300 F.) I still have some scrap pieces of W2 from the same stock, and could heat treat one and then compare to the 1084, now that I'm a lot better at this trade than I was a year ago.
Click to expand...
Yes, ya did something wrong, or had bad W2.

Willie71 said:
If it was more available in my area, I'd use W2 exclusively for mono steel. There is no issue getting a solid performer out if it, and I find it overall superior to 1084 in my limited experience.
Click to expand...
I like 1084, but W2 is noticeably superior! :cool:
 
+1 to Jason's comment on temper specs above.

I've forged from the last two batches of Aldo's 1084fg. With a full quench at 1475F into Parks50, I can tell you that 400 x 1.5hrs x 2X will leave you with a somewhat chippy edge that will appear OK until torqued. Near disaster in the field on a properly thinned mid-sized hunter considering how most guys treat them - around here anyway. I tested a LOT of edges with this stuff and know that, with my gear, I am missing the toughness boat with anything less than 425f x 2X. Even on fine slicers. I routinely temper 1084 higher depending on the intended use of the tool.

Moral is get control of your temps and test to failure. Or stay in the dark about some important stuff like the relationships between HT and usable geometry. This is where the good stuff lives IMHO.

As far as thinning the edge post HT, I too suggest that you forget filing. It will be the last job that file does (poorly) as you've probably discovered. Good quality W/D paper in 80X through 400X on stone, steel or hardwood will hash a 0.02" edge to full sharp in short order.

Test that edge hard before doing handle work, as suggested above, then purposely dull/polish to finish the knife. For me personally, it's a real pleasure to put the final edge on a well finished knife blade processed this way - AFTER the leather is done!

Best to you.
 
Wow, thanks for the replies. I forgot to mention a few things concerning my heat treatment.......some rather important things. After I profiled the blank, I brought it up to critical and then placed it in KAOwool for a slow cooldown. It was nice and soft to drill and work on. Before austenizing, I brought it up to critical and then let it air cool...then hardened the blade. Just for your info.

My latest blade I took it up to 420. Nice even straw colour with a hint of purple. It is still a BEAR to sand/polish the blade. It is VERY similar to the W2 I did a brine quench. VERY HARD.

Let me propose another question/problem. The area of the blade right next to the ricasso is not hardening as it should. I understand there is more mass here, and you really have to make sure that your heat is at temp, and an even heat all the way across the blade. Using a paint can forge for hardening is a challenge, even on short blades, but definitely doable. It is very obvious this little spot is not hard. You can see the difference in the steel when it's polished. I'm making sure to get that even heat, but I really have to be careful to not overheat the tip. My guess is one of two things.....either I'm not quite up to temp in that ricasso area when I think I am.....or......the canola oil isn't quite doing the trick as Parks would. This is with room temp canola OR 130 degree canola. The last bit of the edge (close to ricasso), maybe about 3/8" is soft because of this issue. Happening every time. Any thoughts on that one? I'm thinking, if it's not the quench, then try place the ricasso area in the hottest part of my "forge", and let it soak in there first, and then let the heat work it's way towards the tip more.....rather than putting the center of the blade in the hot spot. I'm also wondering if I was able to baffle that heat coming in somehow, that I would be able to get a more even heat across the blade and tang....might take longer to get to temp......but if I get better results it's worth a try. Thanks again, gentlemen, for your comments.
 
Take a 1"X 2" piece of kaowool and stick the point of your knife in it. As the thick mass of the blade starts to come up to temp,pull the kaowool off and let the tip come up.

Stan
 
Stan, that's awesome. Thanks for the....um......tip. When I built this forge, I had cut out a slot in the back, as well as the front, for whatever reason. I have since plugged that hole with kaowool, and I should be able to just slide the tip into that wool while it comes up to temp.
 
I had that problem back when I was using a forge for HT. In our caution to not overheat the tip, we don't get the ricasso area hot enough. Stan's kaowool trick, a pipe muffle, or just moving the blade around enough and paying attention should all help.

A little more about the tempering thing, since it came back up. I used to HT 1084 blades in a kiln at 1500, very little soak, quench in vet grade mineral oil. Tempered at 425, it worked just right. When I got some 10 second oil from Maxim, my first blade was chippy. Had to bump the temper up to 450. Depending on how much martensite conversion you got from your HT, your tempering temperature can vary. Conversion depends on the austentizing temp and soak, and also on the quench speed, and you can't usually tell just by rockwell hardness. So, back to where I started, test the edge before you put the handles on, in case you need to bump the temper up a bit.
 
Why has no one questioned the room temp oil? Just curious as I have always seen 125-130 deg. as being the way to go .
Eddie
 
Canola and most other oils work best at 120-130F. Parks #50 and a few other commercial fast oils are best at room temp.

Steels that are low alloy will require the fastest quench time - 1075,1080/1084, 1095, W1/2
Steels with alloy ingredients and higher amounts of Mn will work with slower oils, and aren't as sensitive to the quenchant speed or temperature. That said, all oils should be used at the recommended temperature.

What I see more often is a quenchant volume problem with folks who use a 2BF or similar mini-forge for HT. They use a quart jar or soup can to quench in. It takes a minimum of one gallon of oil to properly quench any blade, and more for a large blade. I usually say to have a minimum of three inches of oil around the blade in all directions. That means a small blade would need about a 6X8" quench tank. A 6" ID pipe filled 8" deep with oil is one gallon. A #10 can is about the same.
 
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