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In MemoriamPermalink Reply by Robert Burris on June 20, 2012 at 15:45

Thanks Hal, I hope everything works out. I just want a basic info to beable to explain the benefits of forgeing steel. I will give you all the credit you deserve, I certainly can't explain it on my own. A forged blade is such a great thing and is sort of a lost art now days. Thanks for your help, we'll see how it works out.

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Permalink Reply by Herb Hoover on June 22, 2012 at 20:43

 I hope this helps.

Hunting Knife Considerations

Hunting Knife Blade Steels

Modern tool steels are a wonder. They can be hard, wear resisting, and tough at the same time. They can also be stainless and corrosion resistant. There is no super steel (see these topics on my FAQ page and Blades page for details about steel hype), and your fine hunting, fishing or field knife must be selected carefully. Let's look at the steels from a hunter's and fisher's standpoint individually.

• Plain Carbon Steels: These are the traditional long-time hunting steel types and are classified in the Machinists' Guide as Standard Carbon Steels. Before stainless steels, these high carbon steels had achieved a reputation for edge holding, sharpness, and wear resistance. Steels like 5160, 1095, and 1025 are low in alloys, easy to work with, and cheap. They are used because they can be hand-forged and have a relatively low critical temperature and are easy and forgiving to work with. I rarely use them because there are so much better alloy steels on the market that will offer increased wear resistance, increased corrosion resistance, and higher toughness at a higher hardness than plain carbon standard steels. While in the past these were worthwhile steels, they can not hold a candle to modern, high alloy tool steels, chromium steels, tool steels, and high technology steels available today. In the hunting realm, most knives made of plain carbon steels today are used in plain, simple, hand-forged, inexpensive, and primitive knives. While there is still a following for this type of knife, this is not a type I make.
• High alloy cold work tool steels: In this steel type, I mostly use O-1, an oil hardening high tungsten-vanadium alloy tool steel which is classified as a "cold work" tool steel. Please remember that not all O-1 is the same; some versions from some suppliers contain little tungsten and no vanadium at all. The O-1 I use can be made both hard and tough, ground very thin, is tough, and yet can be sharpened in the field with ease. It is able to achieve and hold an incredibly sharp edge with very little stonework, and you don't have to be an expert to sharpen it. It's drawbacks are that it is not stainless and will rust if not cared for, and is not as wear resistant as the high chromium stainless tool steels. It's the least expensive of the tool steels I use, though it is not cheap. It blues well for a subdued look, and some hunters prefer the mottled, dark, seasoned patina it achieves after several years of use. Because it is moderately easy to sharpen, bringing up the fine edge in the field is no big deal. O-1 is NOT a plain carbon or high carbon steel, it is a true high alloy tool steel, with significant amounts of alloying elements like tungsten and vanadium, so this strong steel holds a very good edge, much better than plain carbon or high carbon steels.
• High chromium martensitic stainless tool steels: Predominately, I use 440C. Actually classified as SAE 51440C, This is a great steel, and I use it for most of my knives. It is often used in industry for corrosion resistant ball bearings, wear, and valve parts. It has universal appeal, being capable of both hardness and toughness, has the highest corrosion and stain resistance at the highest level of finish, and is very wear resistant. It is tougher than O-1, so can be ground in a thinner cross-section and thus is capable of a stronger edge when ground thinner. It is more wear resistant, consequentially, it is not easy to field sharpen. The idea here is that your knife is sharp and wear resistant for several hunts, and should not need sharpening in the field. The high chromium content of this steel allows a very fine mirror finish, which is easy to clean, and is highly corrosion resistant. Of course, even stainless tool steels can rust if not cared for, or if stored with blood, tissue, or wetness in a leather sheath. Read more about corrosion and stainless steels on my knife care pages here and here. Care is minimal though, since 440C has up to 18% chromium. This is the only way to go for a fishing knife, as it has the highest corrosion resistance of any of the custom knife tool steels when mirror finished. 
• High molybdenum martensitic stainless tool steels: What I'm talking about here is ATS-34 (or 154CM). It's essentially the same as 440C, but three percentage points of chromium have been replaced by molybdenum. This makes this a very tough tool steel, that is, resistant to breakage at higher hardness and thinner cross sectional dimensions. It's still stainless, though not as stain resisting as 440C, but it can be made a lot tougher. I emphasize can be made, because it's up to the knifemaker to set the final hardness and temper depending upon the blade geometry and intended use. See my "Blades" page for more details. ATS-34 is hard to field sharpen, so your ATS-34 knife must be thin and sharp enough for your field use and hunt. It can be used for fishing knives, and perform quite well, as the cross section of the knife blade can be made thinner than 440C and still be more fracture-resistant. But the trade-off here is stain resistance, as blood, orange juice, tomato juice, or other acidic fluids can corrode it over time. ATS-34 takes a beautiful polish, which makes for a fine looking knife that is easy to clean.
• Crucible Powder Technology high molybdenum martensitic stainless tool steel: This is a newcomer on the market, specifically CPM154CM. This is a powder metal version, made by sintering together at high heat and pressure powdered components of the alloy for a more even distribution of alloy components. This is a great steel, with the same properties of ATS-34 above, but with greater uniformity and capable of a better finish, higher corrosion resistance, and improved performance. This steel is capable of a breathtaking mirror finish with no visible grain structure. The drawbacks to this steel are the higher cost and the limited sizes for projects.
• Cold work high carbon, high chromium die steel: The steel here is D2. D2 is an older steel, originally used for dies to press and stamp and cut out other metals, and is also used in ball bearings as the load surface. It can be made to be one of the hardest, toughest, most wear-resistant tool steel blades. It has so much carbon and enough chromium that in the crystalline structure of the steel, in addition to iron carbides forming, forms chromium carbides, creating a structure of extremely hard particles, leading to very high wear resistance. This wear resistance is so hard that the knife cannot usually be field sharpened, which may be a drawback. The steel is also not a true stainless, only stain resistant as it has only 12% chromium. So blood, tissue, acidic fluids will corrode and stain this metal. The crystalline structure is also apparent in a high polish, and the surface displays an "orange peel" type of pattern. It is also expensive and limited in available sizes of stock. It's more expensive to cut, grind, mill, and finish also.
• Crucible Powder Technology high vanadium tool steels: Mainly I use CPMS30V and CPMS90V: Mostly used in industry for plastics injection molding dies, these crucible powder technology tool steels are formed as a powder under tremendous heat and pressure for more uniform and concentrated alloy elements. The advantage of this in both of these steels is high vanadium content, approximately 3% for the CPMS30V and 9% for the CPMS90V. This forms an even distribution of vanadium carbides when properly heat treated, leading to an incredibly wear-resistant cutting edge. Unfortunately, they are almost impossible to sharpen in the field, and may take motorized equipment to sharpen. This is fine if you go to the field with a sharp knife, but every knife eventually dulls, so it's important to make sure it's sharp before the excursion. Though CPMS30V has a higher corrosion resistance on paper, it is not so in reality, as it can not be mirror finished to any effective degree, and a rougher surface simply corrodes more easily by having increased surface area and tooth to hold debris and corrosives like blood and moisture. So, in practice, a mirror finish on 440C, ATS-34, and CPM154CM is more corrosion resistant overall

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Permalink Reply by Madhura Senevirathna on July 8, 2012 at 1:03

thanks everybody,for valuable contributions. 

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