1084 tempering

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KnuckleDownKnives

KnuckleDownKnives

Time to make the doughnuts..
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Sorry if this has been covered, but I just heat treated a knife made its alsdos 1084. Heated to just above magnetic and quenched in canola oil. Tempered at 425* twice for 1.5 hrs and it's still hard as a all get out. A file still skates off of it. Any idea on what to do? The handle is golden brown where it's not hard and the blade has a blue color in spots.
 
Is your ovens temp accurate? It's your file sharp? It's going to be pretty tough to file when tempered.
 
If it reached full hardness, 425 temper is still about Rc60. A file will not bite in much if at all at Rc60.
 
Why do you want to go softer? Aldo's 1084 works great using the good old 1500/400 recipe.
 
Maybe more like 59-60 whereas the 400 supposedly gives you 60-61.
Willie71 said:
If it reached full hardness, 425 temper is still about Rc60. A file will not bite in much if at all at Rc60.
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If fully hardened, 1084 will be at Rc 61-62 with a 425°F temper. 450° will yield Rc 60-61.

After HT all finishing has to be done with abrasives ... either sandpaper, belts, or stones. Files are only for pre-HT shaping.

Using good quality sandpaper like the 3-M wet-or-dry or Rhyno-wet will make the process fairly fast. Use a hard backing block behind the paper and change the paper often. Sanding with water with a few drops of dish soap added is a good practice. It makes it faster and leaves a smoother finish.

The rule for sanding is - "Use sand paper like it was free".
 
This is my first heat treated blade with known steel. I have never worked with anything else other than old file knives. I didn't realize it would be this hard after temper.
 
The color had me questioning it too. The blue color in the blade instead of the golden brown color. It just still has that feel if I droped in on the ground it would break. Guess what I'll do is test a coupon with the exact same process I did on the blade to feel better about it.
 
Tempering colours are really innacurate. Any contamination on the blade will change the colours from what is expected. Don't rely on them.

Your experience shows what is preached over and over here. 1084 will give you a better blade than a higher carbon steel unless you have the equipment to fine tune the heat treat of the higher carbon steel.
 
The RC numbers Stacy posted are very close to what I am getting with most low alloy carbon steels. I am finding the "charts" are slightly off, as I think we knife makers are achieving a higher level of hardness post quench than what the "charts" go off of. 400F, according to "charts", is 60-61, but I'm getting around 63.
 
samuraistuart said:
The RC numbers Stacy posted are very close to what I am getting with most low alloy carbon steels. I am finding the "charts" are slightly off, as I think we knife makers are achieving a higher level of hardness post quench than what the "charts" go off of. 400F, according to "charts", is 60-61, but I'm getting around 63.
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I'm finding that too. I'm getting 1-2points higher than what is listed on Kevin Cashen's site for 1084. I don't use a lot of 1084, but am doing a hunter right now, and 400 gave me Rc62/63. This is from the older batch that was 0.87 or 0.89%c. I can't remember the exact number in that batch, but there was a bit higher carbon than expected. The newer batches were closer to 0.84 or 0.85%c iirc. The older batc was the one where people were having trouble with the 1/4" stock. Normalizing and cycling fixed it.
 
Interesting, Well, it still works very well at 62/63. I still have stuff from the first batch that also had a bit more vanadium IIRC. I also have a nice pile of that old 1 x 1/4 Schrade 1084 that Aldo got form the bankruptcy sale. This does make me wonder how hard my 1084/15N20 damascus is getting especially with kitchen knives which I give a 1500/375 treatment with Parks #50. :eek:
Willie71 said:
I'm finding that too. I'm getting 1-2points higher than what is listed on Kevin Cashen's site for 1084. I don't use a lot of 1084, but am doing a hunter right now, and 400 gave me Rc62/63. This is from the older batch that was 0.87 or 0.89%c. I can't remember the exact number in that batch, but there was a bit higher carbon than expected. The newer batches were closer to 0.84 or 0.85%c iirc. The older batc was the one where people were having trouble with the 1/4" stock. Normalizing and cycling fixed it.
Click to expand...
 
One thing to remember when seeing Rc numbers on posts is that they are all taken on different machines. Knifemakers rarely have calibrated machines ( checking on a test block is not calibrated). The difference between machines can always be 1 point, and frequently is 2 points. Add to that the fact that even two knives from the same batch may test differently.

The point is that if you consistently get a Rc 60 - or a Rc62 - it means that you have a HT regime that is well tuned and produces repeatable results. You can try adjusting things to change the final hardness number, but the better method is to test the blade with a brass rod test as well as rope cutting to see how the steel is performing. This is the results that matter ... not the number on a machine. Only change things if the test results don't give you the desired edge type.

Final comment:
There is no one edge that does it all, and no one Rc hardness that is perfect. Each edge has a specific use and the hardness is only one part of that. The combination of edge geometry, overall edge thickness, and steel hardness vs toughness is what makes one knife superior to another. A Rc 65 Yanagi-ba may be as close to te perfect slicer as possible, but the same hardness would fail miserably in a camp knife. It is a lot more than just numbers.
 
Considering I don't have an RC tester, the exact numbers are at this point irreverent to me. I just want to make sure it's good. I'm going to to a test coupon with as close to the exact process I did and put the piece in a vice and try to break it. Depending on how that goes I may get my friend at Tupperware to bring it in and test it on their machine just to get a number ans see where my process is at. Being as this is my first experience making a knife with known metal this will be beneficial to my learning experience. I can tell at this point there is a HUGE difference in the metal than the files I have made previous knives with. This is much harder. I'm looking forward to the next few days as I get back in the shop to start finishing this one up.
 
Stacy E. Apelt - Bladesmith said:
One thing to remember when seeing Rc numbers on posts is that they are all taken on different machines. Knifemakers rarely have calibrated machines ( checking on a test block is not calibrated). The difference between machines can always be 1 point, and frequently is 2 points. Add to that the fact that even two knives from the same batch may test differently.

The point is that if you consistently get a Rc 60 - or a Rc62 - it means that you have a HT regime that is well tuned and produces repeatable results. You can try adjusting things to change the final hardness number, but the better method is to test the blade with a brass rod test as well as rope cutting to see how the steel is performing. This is the results that matter ... not the number on a machine. Only change things if the test results don't give you the desired edge type.

Final comment:
There is no one edge that does it all, and no one Rc hardness that is perfect. Each edge has a specific use and the hardness is only one part of that. The combination of edge geometry, overall edge thickness, and steel hardness vs toughness is what makes one knife superior to another. A Rc 65 Yanagi-ba may be as close to te perfect slicer as possible, but the same hardness would fail miserably in a camp knife. It is a lot more than just numbers.
Click to expand...

I agree with what you are saying, but what I am referring to is that s35vn, 3v, 80crv2, O1, Aeb-l and 52100 all come out as expected with the charts. 1084, 1095, and W2 are all out by a couple points looking at the charts. I think the lower austentizing temp now used is preventing retained austentite. 15n20 is inconsistent with some batches requiring higher tempering temps than expected.
 
I agree with you Wilie. What I was pointing out is people are often over concerned with the numbers ... not the actual real use test results.
 
jdm61 said:
Interesting, Well, it still works very well at 62/63. I still have stuff from the first batch that also had a bit more vanadium IIRC. I also have a nice pile of that old 1 x 1/4 Schrade 1084 that Aldo got form the bankruptcy sale. This does make me wonder how hard my 1084/15N20 damascus is getting especially with kitchen knives which I give a 1500/375 treatment with Parks #50. :eek:
Click to expand...

Wasnt Aldo's old stuff called 1084F and 1095F? the "f" being for fine grain because of the vanadium?
I also had a bunch of 1084 that was before Aldo's time..I bought the last 6 sticks that Admiral had probably 10-11 years ago..They put it on clearance for something like $6 for a six foot long stick that was 1/8" x 1 1/4"..I got 36' of it for something like $60 shipped
 
Well said.

Stacy E. Apelt - Bladesmith said:
One thing to remember when seeing Rc numbers on posts is that they are all taken on different machines. Knifemakers rarely have calibrated machines ( checking on a test block is not calibrated). The difference between machines can always be 1 point, and frequently is 2 points. Add to that the fact that even two knives from the same batch may test differently.

The point is that if you consistently get a Rc 60 - or a Rc62 - it means that you have a HT regime that is well tuned and produces repeatable results. You can try adjusting things to change the final hardness number, but the better method is to test the blade with a brass rod test as well as rope cutting to see how the steel is performing. This is the results that matter ... not the number on a machine. Only change things if the test results don't give you the desired edge type.

Final comment:
There is no one edge that does it all, and no one Rc hardness that is perfect. Each edge has a specific use and the hardness is only one part of that. The combination of edge geometry, overall edge thickness, and steel hardness vs toughness is what makes one knife superior to another. A Rc 65 Yanagi-ba may be as close to te perfect slicer as possible, but the same hardness would fail miserably in a camp knife. It is a lot more than just numbers.
Click to expand...
 
Yeah, I think he may have called it 1084 FG. He had found some big stock 1095 that the called FG. My recollection is that the original batch of 1084 had a vanadium content more like the low end of the 1086M range, like maybe .015%, whereas the current stuff is listed at .004V and .153 Cr with a tiny pinch of nickel. IIRC, some guys said that it did not have as much manganese as the current stuff or old stock 1084, so it didn't get quite as black in the etch. I have made a few monosteel blades form that early tuff and it works quite well. I know one guy who made burly bushcraft knives form it to good effect.
Kentucky said:
Wasnt Aldo's old stuff called 1084F and 1095F? the "f" being for fine grain because of the vanadium?
I also had a bunch of 1084 that was before Aldo's time..I bought the last 6 sticks that Admiral had probably 10-11 years ago..They put it on clearance for something like $6 for a six foot long stick that was 1/8" x 1 1/4"..I got 36' of it for something like $60 shipped
Click to expand...
 
I talked with my friend at Tupperware last night who has access to their rockwell test equipment, once I get all of the decarb cleaned off and get it to him he's going to test it for me. Is 220 good enough for him to test, or should I bring it to a higher grit? Hoping to get to it tonight, as well as doing a test coupon.
 
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