three steel damascus

[Riley White]

I have been thinking about a way to make a very tough knife (I know all Damascus is tough) with a core that would give the knife a very strong edge holding capability. This is what I propose to do. The main part of the knife would be 1095/L6 while the core would be 52100. After I hammer the 1095/L6 out into 160 layers I would part it one last time and put a layer of 52100 in the middle and weld it. I chose 52100 for the core because of the reputation it has for edge holding. The others could also be 5160/L6 instead of 1095/L6. What do you think?

[Ed Caffrey]

It should work. I do a lot of "San-Mai" type blades that are 1080/15N20 damascus with 52100 cores. You have to be careful with welding temps (52100 doesn't react well to overheating), but other than that I've had great success with it.

[Larrin]

Why don't you use something that doesn't get as hard? Using steels that only get to 40-55 Rc would give you the maximum toughness, while having the hard core would give it strength too.

[Riley White]

I thought about that but to be honest I don't know which steels would do that. I would be oil quenching and temporing the 52100 back to about RC59.

[Larrin]

Use one of the lower carbon simple steels (1018 to 1050), pick which one you want according to what you have and what hardness you want. Then put those with nickel, a203e, or pure iron, or a lower carbon steel, like you could use 1050 and 1018 together.

[DiamondG Knives]

Ed
This may be a blind ended question. But is there a simple way to know where you are on the heat without a pyrometer? When my flux begins to "sizzle" is when I feel Im at a welding temp, would this be too high a temp for 52100? And are there any cycles that will ensure that the steel is back where it should be to be on the safe side? Or is 52100 just "done" if it gets too hot??

Thanks and God Bless
Mike

[Riley White]

Yeah, Ed, I would like to know those things too.

[Burke]

I am not Ed but I do know a thing or two about 52100 so here is the way that I would do it. After I had my welded bar I would thermal cycle the steel for five or six times. This is just taking it up past critical and letting it cool to below critcal in still air. you don't have to let it cool all the way just until it is black. Then I would heat the bar to above critical and quench it in room temp oil a minimum of three times. Again you don't have to let the bar cool all the way down just take it to below eight or nine hundred degrees. You are nit trying to harden the bar just fracture the grain boundries for finer grain. Then give the bar a full normalizing heat. then aneal it and grind your knife or what ever and follow the heat treatment that works best for you.

[Riley White]

I think this is turning into a 52100 thread, but oh well. I have another question for Ed or Burke or whomever. I haven't hardened this knife yet but I have hammered it out and heated it once more and let it cool. I then ground the blade out. There were no problems but it sure is hard. Will there be any problems with it and should I do something before hardening the three times Mr. Fouler says to?

[Burke]

As long as it has been normalized you shouldn't need to do anything else. If you are unsure then I would normalize again. Spherodized 52100 seems to be easier to work with than anealed. To spherodize heat to just below nonmagnetic and hold for at least one hour. Let cool as slowly as possible.

[raker]

The temperature that is too "hot" for the 52100 is a light yellow. To find out for sure, take a var and heat to almost white, hit with hammer. If it fractures, you are in the "too Hot" range and don't get it that hot again. Or it will fracture again. Once you see the temperature that is too hot, you will not hit it again at that heat. You can let it cool some before starting to forge again. The piece I had was the first stack of damascus and was distracted for just a bit too long. Half of the billet fractured. I still have it for a reminder. Heat color is a personal thing and it is very difficult to tell some one what it looks like when it is too hot. Kind of like knowing how much pressure to exert on a 1/4" bolt before it twists off. You have to do it once to know for sure.
I would go for the low carbon on the outside if that is what you want. Just remember that after 3 or 4 heats, you will have some carbon migration and it may soften the center more than you would like. You could put a layer of nickel between the 52100 in the center and even wrought iron on the outside. I have a piece that I have been planning on doing it to but hadn't thought of the nickel between to keep the carbon from migrating. Might work, must try it some time.

[Riley White]

Mr. Burke thank you for what you said. I thought I was fairly well informed on most of the non stainless stuff but I don't know what spheroized means as far as its ability to be worked or how it reacts to what ever. I just know what they say about the shape and state of carbon in the steel.

[Burke]

Let me see if I can get this right.

normalize; heat to nonmagnetic and let cool in still air. This is a grain refining step. think of it as taking a beer bottle and busting it up in a sack making fine sharp edged peices.

anealing; heat to non magnetic and hold for a period of time and cool very slowly. This would be like melting all of our glass and cooling it so slowly that the small grain that we made forms crystals while cooling fusing all of our glass back together but keeping the sharp edges of the grain/glass crystals.

Spherodizing; heating the steel to just below critical and hold at that temp for a time. This will allow the small grain peices to form up into balls or spheres so there are no sharp edges to the grain. this also makes the steel very soft and easy to machine. In some of the alloys that have a tendency to air harden/5160 and 52100 in this case, shereodizing makes the steel easier to grind than anealing. I realize that this is not an ideal analogy but it is the best that I can come up with. I am sure that someone else can explain it better than I. Maybee they'll jump in here.

[Ed Caffrey]

Hi Bill!

Thanks for jumping in on this....I got wrapped around the axle, and neglected to check back in on this thread.

Bill said it better than I could have.....I agree with everything he's mentioned.
About the only thing I can add is to tell you that for me, when welding 52100, its almost an instinct thing. I've screwed up enough 52100 through over heating that I basically zone everything else out, and concentrate intensely on what's happening in that forge. It's also the main reason that I added a digital pyrometer to my welding forge. The first few times I goofed up a 52100 blade via overheating, I was baffled. The steel showed no outward signs of damage, but when I went to test the blade, it just wouldn't cut. Over time I came to understand what I was doing wrong, and adjusted accordingly. Thermal cycling can save a 52100 blade, but I have discovered that if you go too far with the heat, you might as well start over with a fresh piece.
There is a point, where thermal cycling will not fully recover the steel, and if you push ahead, your only going to wind up with a mediocre blade at best. This is especially true if your using 52100 for a core material in a San-Mai type blade construction. The trick is to get the blade together, and get it done in as few controlled heats as possible. Then thermal cycle the daylights out of it.

[Burke]

Hi back at ya Ed.

I just thought that maybe I could help out.

On welding 52100, I am using a pyrometer in my welding forge also and have had the best luck using a super low heat and a long soak. What I mean is that instead of welding it at say 2150 and allowing it to soak ten or fifteen minutes. I set the forge so it is running at 1850 to 1900 and let the billet set and soak for forty five minutes to an hour. This does result in large grain forming but by using inter forging quenches and thermal cycling after forging I am getting good performance. I have not sent any blades that I have done this to in to be tested for grain size though. I have broken a few blade and the grain size apears to be satisfactory . One more thing. Since carbon migrates (at the rate of .020 thousanths per hour I believe) be sure and leave some extra sacrificial steel around your cutting edge at least. You are also going to lose some carbon to the jacket steel but this can be addressed by using nickel or high carbon jacket. If I am in error here somebody please step in.

Bill