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"Pocketknives
to Broadswords "
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There's no such thing as the perfect blade, but finding an appropriate steel can help ensure that any knife will perform. By Durwood Hollis written for the AMERICAN RIFLEMAN special knife section Aug. 2002.
Steel is the very essence of a knife blade. A combination of iron and diffused alloys, it evolves through a process of forging, quenching and tempering. This blending of components cannot exceed the performance envelope of its primary elements. Blade steel can be divided into two categories: carbon steel and stainless steel. Carbon steel in its most basic form contains iron with the addition of carbon and manganese. The single factor that separates carbon steel from its stainless brethren is a minimum of 13 percent chromium in the latter's formulation. Other elements-such as carbon, cobalt, copper, manganese, molybdenum, nickel, phosphorous, silicon sulphur, tungsten and vanadium-are found in many blade steels. Each element lends its own attributes to the overall mix. Carbon Steel: While this material will rust, many cutlery manufacturers use epoxy coating, bluing, Parkerizing or molecularly bonded materials to provide a measure of protection from staining and oxidation. 1095: This steel is extremely tough and is often used in hardworking knives, swords, hatchets and axes. In addition to blade steel use, 1095 carbon steel can be found in trunk springs, files and road grader blades. A simple steel, but one that can handle substantial mishandling and still provide good service. D-2: What sets this carbon steel formulation apart is its strong chromium content (12 percent). While not quite stainless in nature, nonetheless, it is very resistant to staining and has exceptional resistance to wear. It is a solid choice for blades that will be subjected too hard use in the field. Stainless Steel: To meet the minimum definition of "stainless steel," the composition must contain at least 13 percent chromium in its makeup. While not totally rust-free, stainless steel does offer enhanced protection from environmental invectives. 420: While most stainless blade steels are rather difficult to sharpen, 420 stainless is one that responds quickly to edge restoration. It has a relatively low carbon content (0.15 percent), so it is less wear-resistant than other stainless steels. It is at its best when tempered to a relative hardness of Rc 52-56 (Rockwell). Furthermore, the chromium content (13 to 14 percent) is at the minimum end of the "stainless" scale. Along with 420HC, the high-carbon version, 420 is a solid, affordable choice that demands only limited maintenance. 440A: In this stainless composition you'll find an increase in both the amount of carbon (0.6 to 0.75 percent) and chron-dum (16 to 18 percent) over 420 stainless steel. In addition, 440A has a quantity of molybdenum (0.75 percent) that enhances the basic properties of the carbon content and improves resistance to oxidation. The increased chromium content amplifies the nature of the carbon and provides resistance to wear and corrosion. 440C: This steel possesses a greater carbon content (0.95 to 1.20 percent) than either the 420 or 440A formulalions. The addition of the increased carbon provides gains in wear resistance, which results in enhanced edge retention over either 420 or 440A stainless steel. It is usually tempered to RC 57-58 for optimum use. AUS-8: This offshore-produced steel has a higher carbon content (0.70-0.75 percent) than its AUS-6 sibling, which gives it greater edge retention. There is also a small amount of molybdenum (0.10-0.30 percent) in this steel, which is absent in AUS-6 stainless. Importantly, this element adds to the corrosion resistance, strength and hardness of this stainless composition. AUS-8 achieves its optimum hardness at Rc 58-59. 154CM/ATS-34: These rugged stainless steel twins feature a high-carbon (ATS-- 34/1.05 percent, 154CM/ 1.00 to 1.10 percent) content. The enhanced carbon inclusion increases hardness, wear resistance and edge retention. Both can easily be brought up to an edge-retaining hardness of Rc 59-61. Since the surface tension of both steels is greater than other stainless compositions, both are laser-cut rather than being fine-blanked. Grinding and polishing of this steel require additional time, which adds manufacturing cost and will be seen in a higher retail price. The only other negative feature of either steel is they both have only a minimal chromium content (ATS-34/14 percent, 154CM/13 to 15 percent). The Final Word: The average knife user may not easily recognize the subtle differences in various blade steel formulations. The longer you use any knife, however, the more inherent properties of the blade steel will be manifest. To make gains in one area, you'll often have to compromise in another.
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