Steel Used
INFI is a proprietary steel and heat-treat protocol developed by Busse Combat Knife Co. It is ONLY available through Busse Combat.
Some facts and information about INFI.
Hardness
Although hardened INFI knives are 58-60 Rc we have yet been able to chip an edge. The edge can be dented or misaligned but its high level of malleability at such high hardness has never been duplicated by any other steel that we are aware of or have tested.
Flexibility
In one of our performance tests, we bend a Battle Mistress 35 degrees in a vise and it springs back to true. Why would we do this? What does it prove? What is the benefit to the customer? Not only does this test demonstrate the enormous toughness and lateral strength of an INFI blade but, because our hardness is homogenous and not differential, it demonstrates the amount of lateral strength and "spring" of INFI all the way to the edge. That means that edge of the blade will possess this same toughness. INFI is the only knife steel ever tested that has achieved such high levels of lateral strength with a homogenous hardness of 58 - 60 Rc. No other steel has even neared this performance level.
Edge Retention
Many so-called knife experts have heralded the "wear resistance" of a steel as the key to edge retention. This may very well be true if a knife is designed and intended for the cutting of soft materials ONLY. However, we have never inspected a dull knife and found the edge to be perfectly smoothed away, like a ball bearing. Instead what we find are microscopic chips where the edge has broken or chipped away like glass after having impacted against bone, gravel, or other hard surfaces. This micro chipping dictates that the edge be reground during the resharpening process, which will ultimately lead to a thicker edge and a radical change in overall blade shape. Steels with high wear resistance normally score fairly low in shock resistance, lateral strength, and overall toughness. INFI scores very high in ALL of these categories.
Sharpening
INFI's high level of chip resistance also makes it the easiest steel to resharpen by hand that we have ever encountered. One of the great features of INFI is that simply stropping away from the edge (the way a barber strops a straight edged razor) on a ceramic stick is basically all that is required to resharpen INFI. Since you're not chipping steel off the edge there is no need to grind any steel away. This feature of INFI will, likewise, allow you to keep the same overall profile of the knife for a much greater period of time.
How does INFI compare to other steels?
While this question is simple, the answer is somewhat complex. INFI represents what we have always dreamed of in a knife steel. Tougher, by an enormous margin, than any other steel we've ever tested. It has unparalleled edge holding under high impact and in cutting tests, and shock resistance that begs you to "bring it on". INFI has an ease of re-sharpening that you have to see to believe and higher levels of lateral strength at high hardness than have ever been achieved by any other steel. We have published our test results and our testing methodology. We have video taped all of these tests and play the video at the knife shows we attend. More importantly, we have duplicated these performance tests in "LIVE" demonstrations at many trade shows throughout the United States. We encourage all manufacturers to put their products through our tests and to publish their results. If you want to know how another maker's knife will compare to a Busse Combat knife, ask the other maker to duplicate our tests in a "live" demo.
Is INFI stainless?
INFI is technically not supposed to be, however, INFI has demonstrated very high levels of stain resistance in many different climates. Uncoated blades have been tested for years in Alaska and have made their way into the wilds of British Columbia, the High Sierras and tropical rain forests. No rust in Alaska or British Columbia! No rust in the High Sierras, even when exposed to great quantities of blood and left in the wet grass overnight. The tropical rain forest, which has been known to rust plastic (just kidding), did offer the toughest of the environmental exposures and a light speckling of surface oxidation did occur but was easily removed in the field with a hand rubbing of sand and water. No deep pitting was reported. When compared to other cutlery steels in salt spray tests, INFI faired better than ATS-34 and D-2. Although all three grades exhibited surface oxidation, the INFI was not deeply pitted as was common in these other two grades. So, although INFI is not technically a stainless steel, it is certainly not a rust aggressive steel. Couple this with a minimal amount of care and you've got a fairly maintenance free knife. With a steel like INFI it's easy to understand why we offer the toughest guarantee in the business. We guarantee against any and all unintentional MAJOR damage forever.
Blade Coating
The blade coating is a wrinkle/crinkle coat. Through extensive testing, it has been determined this is the best coating available for knives seeing heavy use. This coating is ideal for extreme use knives because the raised areas will take the initial wear and begin to smooth out and after much use that part of the blade will still have the finish only smoothed out. Only after the finish has smoothed considerably do you begin to see any of the coating begin to wear off. The life of this rough finish is extended when you compare it to smooth finishes of the same thickness.
Other advantages of this type of coating are it is less reflective than smooth coated or non-coated knives. It also resists stains and corrosion far greater than non-coated knives.
Handle Materials Used
Micarta
Our micarta handles are offered in paper, canvas, and linen. Micarta is a composite material made from layers of fabric or paper impregnated with thermosetting resin through the use of heat and pressure to bind the layers. As micarta is durable, rigid, and electrically insulating, it is a perfect choice for knife handles. Difference between the three types of micarta are generally aesthetic in nature and therefore a matter of personal preference. One noticeable difference is the color between the micartas. Canvas micarta generally appears duller while linen and paper are brighter. Paper micarta can take a high shine. The color differences are easier to spot on darker micartas such as black. Another difference is the feel of the micarta. Canvas feels rougher than linen and paper which some prefer for slip resistance when knives may be used in conditions where they will become wet.
G-10
G-10 is a glass-based epoxy resin laminate. Production is similar to micarta, only instead of paper, linen, or canvas, layers of fiberglass cloth are soaked in epoxy resin. Again, heat and pressure are then used to bind the layers. G-10 is an electrical grade laminate that is lightweight, strong, and virtually impervious to moisture and climate issues. It has a high impact strength and resists cracking in even the most extreme conditions.
Heat Treat and Tempering Processes Used
Busse Combat knives are exposed to over 60 hours of heat treating and tempering. It is in this process that the very soul of a blades performance will be born. It can also be the most expensive process involved in the making of a fine blade.
Sadly, the knife buying public has been led to believe that Rockwell Hardness is some sort of gauge by which to determine performance. This is ridiculous. Following standard ASTM heat treating and tempering protocols, a blade made from a standard tool steel can be "properly" heat treated and tempered in less than 1-1/2 hours and brought to a hardness of 57-59 Rc.
But what does that prove? One of our Swamp Rat division blades that has received our proprietary heat treat and tempering protocol of over 40 hours will also test out at 57-59 Rc. This fact is that one of our Swamp Rat transversion wave tempered blades that tests out at 57-59 Rc will greatly outperform a standard heat treated knife blade out of the same material that also has a 57-59 Rc hardness. Now imagine the performance of a Busse Combat blade that has undergone our proprietary heat treat and tempering protocol of over 60 hours that tests out at 58-60 Rc!
Grain structure and carbide distribution, are the keys to great performance NOT Rockwell hardness!
Cryogenic Treatment
Busse Combat knives undergo a deep cryogenic treatment at over 300 degrees below zero. This deep-freezing of our INFI steel to 300 degrees below for a prolonged period of time stabilizes the microstructure of the INFI. Just as retained austenite is transformed to martensite during the tempering process, the same change occurs during the cryogenic treatment.
Our cryogenic treatment improves the mechanical properties of INFI like hardness, wear resistance, toughness, and resistance to fatigue.