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Tacktical Knives July 2002 Issue GIN5: A Surgical Steel for Knives! There are a lot of steels out there that are perfectly serviceable for knife blades. A cutlery grade steel need have only .5% carbon in the mix to allow it to become hard enough to form a workable cutting edge, but there’s a great deal of difference between a workable cutting edge and a superb cutting edge. A knife that cuts and cuts well can be made from a simple high carbon steel, but there’s a big problem with high carbon steel: it rusts. It’s also possible to make high carbon steel cut better by the judicious addition of some other elements. There are a number of things that can be done to improve high carbon steel – making it resistant to rust by adding chromium is but one of them. Just adding the chromium alone can give high carbon steel added abrasion resistance, hence more edge holding ability. There are other elements that can be added to steel to assist the chromium in its corrosion resistance; nickel comes to mind immediately. Nickel does other things, but it’s best known for helping with corrosion resistance. It’s only logical to assume that steel with a sufficient amount of chromium to become stain resistant, and that has a bit of added nickel for more stain resistance, is steel designed to be used in the harshest environments. Enter GIN5. GIN5 is a product of Hitachi Metals of Japan and is primarily designed for razor blades. Of course, knife blades can be fitted easily into this lineup. In fact, since this steel was expressly designed for service that could quite logically be described as much more severe than what we normally expect a knife blade to endure, using it for knives becomes a no-brainer. GIN5 has .62-7-% percent carbon, more than enough to give it adequate hardness. Then there’s 12.7-13.7% chromium. It takes a least that much to give adequate stain resistance, plus there will be chromium carbides to add hardness and wear resistance. GIN5 has from .2 to .5 silicon, which promotes yield strength and increases tensile strength. There is a .45 to .8 manganese in the mix for hardenablitity, wear resistance and tensile strength. Phosphorus is present in a minute amount, .025%, also for tensile strength, machinability and hardness. Sulfur is there for machinability too. Mentioned earlier, nickel is in GIN5 at .50%. Nickel adds strength, hardness and corrosion resistance. A bit of copper is in the mix, around .10% for added machinability. Designing a steel for specific cutting instruments is a delicate balancing act and it’s easy to see that a lot of thought has gone into GIN5. The razor blades, surgical blades and industrial blades GIN5 was designed for have to operate in some pretty harsh environments. We don’t usually think of a bathroom where a razor is kept as being a harsh environment, but by definition there is a high humidity. High humidity promotes rust; rust is a pure devil to a cutting edge. Never mind what rust does to the rest of the blade; the cutting edge, as in that delicate line of microscopic saw teeth that forms the working part of the knife, suffers from rust first. Rust is also a no-no for blades designed to be used in surgery, so a blade designed to be a surgical instrument needs a high degree of corrosion resistance. Then there’s the strength factor. Blades designed for industrial use have to be strong by definition. Industrial blades are subjected to stresses ordinary knives will never experience, and they are subjected to those stresses constantly. GIN5 is designed (note the number of elements in the mix that add strength) to be strong, especially corrosion resistant, and stay sharp. This steel is used for the insert blades in the TigerSharp system. It is heat-treated, cryo-treated and tempered to 61 Rc, very hard for a knife blade. The insert blades in the TigerSharp system have to be very thin, the whole blade, side plates and insert combined are only 9/64 (0.14) inch thick. A blade this thin, and this hard, has to be strong, hence those added elements that give strength to the steel are there for a purpose. The TigerSharp system allows for insert blades to be replaced in a matter of moments, the inserts are relatively inexpensive ($4.00) so there’s no real need to resharpen the inserts. It can be done, however, if you’re equipped and know how. Sharpening steel that’s abrasion resistant and 61 Rc isn’t for the faint of heart or the ill equipped.
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