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Author Topic: Powdered Metal vs Forged Steel  (Read 18586 times)
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KevinSalonek
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« on: February 16, 2010, 01:02:20 PM »

Powdered Metal vs Forged Steel

Ed must be raising us right?

We have all seen excellent knives made by the Stock-Removal Clan. Powdered metals seem to have promoted their task by producing a uniform distribution of the carbides in this grade.

Something I have come across as interesting to me, is a bottle-neck in one of the worlds newest technologies.

From forging swords that were known for there quality, to gun-barrels that were known for there superiority, grew a process that is now known as the safest process for humanity.

As it seems, there is only one acceptable method of constructing a nuclear containment vessel, just as Ed and Rex school us likewise with blades!....... Link:http://www.bloomberg.com/apps/news?pid=20601109&sid=aaVMzCTMz3ms

Quote
15,000 Tons

To make the 600-ton ingot, workers heat steel scrap in an electric furnace to as high as 2,000 degrees Celsius (3,600 degrees Fahrenheit). Then they fill each of five giant ladles with 120 tons of the orange-hot molten metal. Argon gas is injected to eliminate impurities, and manganese, chromium and nickel are added to make the steel harder.

The mixture is poured into a blackened casing to form ingots 4.2 meters wide in the rough shape of a cylinder. Five times over three weeks, the ingots are pressed, reheated and re-pressed under 15,000 tons applied by a machine that rotates them gradually, making the floor tremble as it works.

The heavy forging is needed to make the steel uniformly strong by aligning the crystal lattices of atoms that make up the metal, known as the grain. In a casting, they would be jumbled.
   

To me it is just fascinating that with thousands of manufacturing processes, hundreds of steels, only one makes it to the top of the 'A' list,,,, or more correctly, is the 'A' list......

FORGING

Quote
`More Art Than Science'

``What they do is an art more than a science, and that's why they're the critical path,'' said Steven Hucik, senior vice president for nuclear plant projects at GE Hitachi Nuclear Energy in Wilmington, North Carolina. His company has already reserved sufficient capacity at Japan Steel's plant to cover its first wave of new reactors, he said.

Japan Steel's most prized products also include samurai swords, with price tags of about 1 million yen.

They're made in a traditional Japanese wooden hut, up a steep hill from the rest of the Muroran factory. It's decorated with white zigzag papers called ``shide'' used in Shinto shrines, creating a sense of sanctity in the workshop.

Inside, as the factory clangs and hisses below, Tanetada Horii hand-forges broad swords from 1 kilogram (2.2 pound) lumps of Tamahagane steel.

``Making a sword emanating peculiar beauty from the dull substance of stone-like Tamahagane steel is bliss,'' he said.

CEO Nagata says the process goes to the company's heart.

``Samurai swords contain the essence of steelmaking technology,'' he said. ``We've inherited this technology and we don't want it to spill outside of Japan.''


It would be to easy to rib here by asking if, 'Powdered-metals will ever catch up to forged Wootz style steels?' , But I would ask what we would rather be stuck in the field with-out a can-opener and a can of beans. Forged steel or powdered-metal blade?    

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Harry Mathews
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« Reply #1 on: February 16, 2010, 07:54:35 PM »

I'm not sure I understand the comparison between "powdered metal" and "forged steel". One is a process of making steel and the other is a process of shaping steel.
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Harry Mathews
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« Reply #2 on: February 17, 2010, 10:06:51 AM »

The way I see it, forging allows control of alignment of the grain of the steel resulting in allowing the maker to dictate the direction of strength. The forged blade, when forged from larger stock results in grain alignment like a tree limb. The greater the rate of reduction by forging the greater the potential for linear or lateral strength.

Powdered metals result in a granular steel, like a sculpted knife made of fine sand, ceramic or clay. I have never tested any of the powder metals, but speak from theory about them.

Any thoughts from those who have tested blade of the powdered metals are welcome.
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Harry Mathews
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« Reply #3 on: February 17, 2010, 07:35:14 PM »

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Powdered metals result in a granular steel, like a sculpted knife made of fine sand, ceramic or clay.
Huh
 
Are you talking about a knife blade made using the sintering process? That's not really what I was thinking about.
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Harry Mathews
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« Reply #4 on: February 18, 2010, 12:34:31 PM »

Yes I was reffering to developed by the sintering process.
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Will
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« Reply #5 on: February 24, 2010, 11:16:33 PM »

I~m not real big into stainless, realy prefer forged blades, but powdered metal does have it~s place.  I~ve been using and testing S30V and CPM 154.  I don~t much care for the S30V, it~s too hard to sharpen for the edge holding gain.  The CPM 154 however is a great stainless and I~ve just about switched over to it completely for the few stainless knives I do.  I~ve been carrying a folder offshore with a CPM 154 blade and it is a great working steel, holds a very good edge(for stainless), is easy to sharpen, and is relativly tough(for stainless)  That said I still prefer carbon steels, mainly 52100, because of the ballance between edge holding, being able to sharpen, and toughness.  The CPM steels go a long way to bringing stainless into the high performance realm and solving the problem of having enough free chrome to make a blade stainless.  But they still fall a little short of a properly forged blade.
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Harry Mathews
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« Reply #6 on: February 25, 2010, 08:27:28 AM »

Charlie and I use a good bit of CPM S30V and CPM 3V in our knives. It is not sintered metal. It is created with a process that mixes the elements that will make up the steel in a powdered form. This mix is melted, poured into ingots and then sent out to rolling mills just like "regular" steel. The process results in a very clean steel with the elements very evenly mixed according to all the information provided by the manufacturer. Grin We haven't found anything better. We have had problems with some other steels including D2, 1095. We also use 1084, 1095,  5160 and occasionally 52100. We haven't found CPM S30V to be difficult to sharpen at all it is very tough and holds an edge very well.

As far as powdered metals "fall a little short of a properly forged blade." I don't see that at all. If one of your requirements of a blade is that it bend back and fourth, that is a function of the heat treatment and a high carbon steel will be better at that than a stainless steel because they aren't air hardening. Go for it. As far as a knife that I will use as a "knife", I will take a blade of CPM S30V every time.

Ed I hope this doesn't get me kicked off the forum. It is just the way I use knives and the places I use them. A carbon steel blade I am working on will rust while I'm gone to lunch. We are constantly re dragging out a blade if it is made of carbon steel. I just finished one of 5160 and will be thrilled when it is gone. While I don't mind stains on a blade that I use, we can't sell one with stains on it and are constantly wiping them down and waxing them to fight the humidity. We make blades out of carbon steel and stainless. We also forge blades as well as use the stockremoval method. Personally I'm glad that the customers seem to like the CPM S30V. Sure makes it easier on us.
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« Reply #7 on: February 25, 2010, 09:48:53 AM »

Harry: I can assure you that nothing you will say will get you kicked off of the form. Discussion and debate are always welcome. We all make our own knives and serve clients who come to us with their individual expectations.

I sincerely appreciate your honest comments about the powdered metals, every steel has its "special" properties, as blade smiths we need to share this information as honestly as possible, I don't have time to experiment with all metals available, nor does any other smith. When each of us does his testing and reports it honestly for the information of all, we as individuals will make knives better suited to our clients.

I know and have experiences like yours with the other steels, that is why I switched to JD 5160, John Deer took care of the quality control for me.

As to rust, I work in a different environment than you, rust is rarely a problem for me. I am doing a little experiment, I waxed a blade heavily with 'Trewax', let the wax dry and placed it in a sheath that had been soaked in water. I kept it wet for a week and no rust appeared on the blade. The blade was an etched 52100 blade. If you get the chance give it a try, I think you will like it and either way, please let me know what you think.

I was waiting and hoping you would expand on your last post.

Thank You!
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« Reply #8 on: February 25, 2010, 02:25:44 PM »

I was under the impression from CPM that S30V was a sintered product made by atomizing the steel and using a hot isometric press to ^forge^ weld the particles together, that they didn~t get quite hot enough to completly melt.

I~ll say this for S30V that I~ve used, it does hold an edge forever, and in fact holds an edge slightly longer than my 52100 blades.  But I can touch the edge up on 52100 a lot quicker and easier than S30V.  Also the ones I~ve tested arn~t nearly as tough or shock resistant.  I will add that they were heat treat by Paul Boss, if I was able to play with the heat treat a bit more at differant hardness levels I might have differant outcomes.  I~ll add that the edge on the S30V that I~ve used doesn~t cut quite as well as most carbon steel blades I~ve tested, not much differance, very subtle, but a differance in feel.

Everything is a trade off, one way or the other.  I still believe the CPM steels have there place, but me personaly I prefer a forged blade.
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Harry Mathews
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« Reply #9 on: February 25, 2010, 05:20:04 PM »

Thanks for not kicking me out Ed. I kind of like it here where makers can have a discussion without flaming egos and drawing pistols, if you know what I mean.

It could be you are right Will. It is my understanding that their steel is actually melted. I have talked with their metallurgist and that was the impression I received from the process described. He could have been just trying to keep it simple for my sake. I?ll press him on it next time I talk with him. I know the resulting ingots are sent to a rolling mill to be reduced to a usable state. I've seen pictures of it.

When Charlie and I first started making knives full time we tried several different steels to determine what we would standardize on. We had some ATS34, D2, 154CM, 1095, 5160 and a few others. We made several similar blades of different steels and sharpened them all to as near the same sharpness and edge geometry as we could. We then started slicing 1/2 inch strips off of a sheet of double thickness cardboard 18 inches wide. We chose cardboard because it was available and the old standard of 1 inch rope wasn't. It worked well and really seemed to be a challenge for the blades. We tested by counting the number of slices a blade would make before that section of the blade stopped easily shaving hair off an arm. (pick a hair out under magnification and cut it off.) The shaving test was tried every five slices. They all did well but the D2 (heat treated by Paul Bos to a RC of 60) far exceeded the others in edge holding. The carbon steel rusted easily but did well in impact tests and edge holding. Around here we just couldn't take the rust. The stainless did well resisting rust but didn?t fare well with the impact test.
 
We picked the D2 mainly for the edge holding ability and the semi stainless characteristics. We hollow ground the edges thin....really thin. We could flex the D2 blades edge with our finger nail.  It held up well dressing out, including boning, from the ground to the freezer a couple of deer with no problems. A side impact test showed it took very little to break a D2 blade. It would also rust easily unless in a polished state and when it did, it pitted deeply. We would also find pits in the metal when polishing.
 
We kept looking for a good steel and came across CPM S30V. It far exceeded D2 in edge holding (we finally just gave up slicing cardboard) and we were unable to break it in a side impact test. We settled on a Rockwell hardness of 59 and have been very pleased. It is not difficult to sharpen with a good diamond stone and strop. S30V also resists corrosion very well. It is not difficult to heat treat using quench plates and it had the toughness we wanted for a blade. We heard rumors of edge chipping with S30V and found that the manufacturers that were using it were not heat treating the steel using the recommended steps. We have never seen edge chipping and use blades made of S30V for our carving knives that are used to carve sambar stag antlers. The edges have to be tough for that.

We decided to see how a hunter with an S30V blade would do in a prying test. We took a 3.25 inch blade drop point hunter made of 1/8 inch steel and hollow ground with a 14 inch wheel and clamped one inch of the blade in a vice. The knife was in a horizontal position. We attached a bucket to the thong hole of the handle and started adding steel weighing each piece. At 45lbs, we removed the steel and the blade had taken a small set in the direction it was bending. We placed the 45lbs of steel back in the bucket and added more. The blade snapped after holding 58lbs of steel for 3 or 4 minutes. For a light weight hunter with a 3.25 inch stainless blade and 4 inch handle we were not disappointed at all.

  

We understand that no steel is suited for all uses and use a variety depending on the requirements of the customer. It sometimes is a challenge to decide what steel would best be suited to the customer?s needs. Many times the customer has picked out the steel for his knife prior to contacting us about making it and often they made a good choice. Sometimes their choice would not be the optimum steel for their use, but they are willing to accept the shortcomings in order to get a certain characteristic they want. Mostly it is a balancing act trying to weigh the good against the bad and coming up with something that keeps the customer coming back for more. That is part of what makes this a never ending search for the perfect steel.   




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Harry Mathews
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« Reply #10 on: February 25, 2010, 06:48:08 PM »

Harry,

Great presentation on you and your brothers method of selecting and testing steels. I sure hope that you are a constant on the KTO. You have a lot of knowledge that is not falling on deaf ears here. Your questioning of my posts been great for getting me to clarify my direction.

Like Ed's work, The Twin Blades have been some of my favorite work that I have seen in the books and magazines and am always glad when your work shows up. Thanks for sharing your lady with us.

Harold Locke
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« Reply #11 on: February 25, 2010, 07:28:38 PM »

Harold like most here, I guess, I love knives. I like looking at pictures of knives and I wish more would post pictures of what they are working on. I learn something every time I see one either because of what I see or what it makes me think of. This is one in 5160 that I differentially heat treated using clay. The blade back is 40 on the Rockwell C scale and the edge is 57. It makes a tough knife, but not one that I would think would bend to 90 deg several times without breaking.
Yep, this is the one that I had to drag out several times and is now sporting a heavy coat of wax.



The best thing about choosing steels is that you aren't stuck with just one. It is not hard to get good with several different steels and most of the good knife steels will make a great knife. While we use mostly CPM S30V or CPM 3V, the knife I made for myself and one that I use every day is forged from 1095 and is not differentially heat treated.
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« Reply #12 on: February 25, 2010, 09:14:42 PM »

Harry: It looks like that knife would balance with a string in the hole. If it does how about trying a little non-destructive experiment for us. Magnetize it and hang it from a string and see how tough it is to get it to indicate North or South. This is something I have wanted to do for years and since you have a knife that looks like it would work and if you feel being part compass would not hurt the knife I would find it interesting. Just another little thing a knife could do and when you get fogged in and turned around it could make a difference.

I do like that you placed the hole where it would not be stress raiser!
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« Reply #13 on: February 25, 2010, 09:57:25 PM »

Those are some good looking knives Harry, I realy like the smaller hunter.  I love to make big chopers and bowies, but realy, the smaller hunters usualy get a lot more of a work out.

It's posible that they've changed the process of CPM, it's been several years since I bought any from them.  Like I said, I don't do many in stainless, but I remember seeing pics of the isometric press, and it looked cool how they were doing it.  Since I can't replicate there process, I'm not overly interested in the process, but do like there steels.

The one real downside for carbon steel knives down south is that any corosion will knock the fine edge off.  If you use it a lot it's not an issue, but put it in your pocket or on the counter for a while after cutting something and you don't wipe the edge it'll dull it a bit.  The only time I've had any real issue with it was with a folder I made to carry offshore.  Didn't do real good in a salt water environment.  So far the CPM 154 is doing great.

I'll second having a good discussion, I figure when you stop learning it's about time to roll over let them chunk you in the grave.  There's more than one way to do something, especialy with knives.  It was a while back my uncle asked me to make him a cleaver.  He was a bit stumped when I asked him whether he wanted stainless or carbon, was he planing for choping bone or for slicing meat.  Intended use realy makes a big differance.
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« Reply #14 on: February 26, 2010, 07:05:03 AM »

It is a little blade heavy but I'll see what happens when I try it Ed. I have always wondered if the orientation of the blade while it is being worked after heat treatment causes some magnetization.
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