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Please Note: this article was prepared in an effort to provide some basic information for those people who are in the market for knife, but do not know a great deal about them. Therefore the information provided is basic, easy to understand and just sufficient to help one select the right knife and steel for their own use. Hence we tried our best to stay away from technical jargons, tables, stats etc. If you are a collector or a knife maker yourself this article will not be of much use to you and you can find more suitable information elsewhere on the net.
These days, the old adage of there is really only 2 types of steel is no longer valid. Modern technology and advances in metallurgy and materials have allowed us to create alloys and compositions to suit a monumental range of applications. From space-craft to simple springs.
Just like the huge range of knife and cutlery designs available today, the range of steel types and grind profiles is also quite daunting.
So where do we start?
Well, once again, lets keep it simple. After all, a knife, no matter how high tech or complex in design is still only a knife, designed to cut, to separate matter. Keep in mind that I am not a metallurgist, nor do I try to be one, however I do know a lot about knives and have done a fair bit of homework.
Most of today’s blade material choices can be (loosely) put into 5 categories:
Is not stainless! “That doesn’t make sense” I hear you say. Well, let me clarify. Stainless in the actual meaning of the word is referring to the ability of the steel to be 100% free from stain and rust irrespective of what it is exposed to. This is a fallacy. Stain resistant is more accurate. Chromium content is what makes a knife stainless, the more Chromium the more stain resistant.
440A has more Chromium and /or less Carbon than 440C and therefore will not rust or stain as easily. But they will both rust if exposed to the elements for long enough. It is only really the extent of rusting that varies.
Stainless steels tend to get surface rust and stop there (unless left in sea water) whereas Carbon steels will pit and be eaten away to the point of structural damage. Stainless steels are a good choice for those that do not wish to maintain their cutlery on a daily basis.
Stainless steels tend not to be quite as tough as Carbon steels and therefore you will see Stainless steel knives usually made of thicker blade stock materials for any given knife. Thin but large stainless steel knives tend to break whereas thin, Carbon steel knives will flex to a greater extent before gross failure. However, good steel quality and good heat-treating practices are usually what make a knife tough enough for heavy-duty usage. Stainless steels still contain carbon, just not as much as straight carbon steels. Thus the higher the carbon content in a stainless steel, the better the edge retention.
A simple steel alloy that has existed long before all others in modern cutlery. It remains as a strong contender in the market for a number of reasons. It is tough, it will take an edge easily in the field and is known for its reliability. Having said this, Carbon steels will rust far more easily and if not looked after, will rust to the point of no return. Carbon steels will also stain when exposed to substances that contain acids, such as food stuffs and meats. When you see old carbon steel knives that have been used to process foods their blades will have a dark grey/black mottled patina finish. This is the same finish that appears after rust has been removed. Fine razor edges will dull without usage due to rust at the edge itself, so keep those blades oiled.
Metals to cut other metals in other words. Tool steel alloys have existed in the manufacturing industries for a long time but have only recently been introduced into the production knife market. Custom makers have used some tools steels like D2 or A2 for many years but have not made it into the limelight as such, with people like Chris Reeve as the exception to this.
Tool steels are a compromise between Carbon and Stainless steels in most areas. They will stain but not as fast as Carbon steels. They are tougher than Stainless steels generally speaking. Their edge holding abilities is where they surpass both carbon and stainless alloys. But it is for this reason that they are usually much harder on the Rockwell scale and therefore are quite difficult to sharpen. This can be offset by the fact that it would not need to be sharpened as much. Once again, steel selection comes down to personal preference.
Beta titanium was really only used on high end diving knives for a couple of reasons. It will not rust…ever. Titanium forms a hard, oxide layer on its surface and stops there. Almost like a self, healing armour plate! Beta alloys are also extremely lightweight and exceptionally tough/strong. Some Naval units employ titanium diving knives because titanium has little to no magnetic signature, paramount for those conducting mine clearance operations involving magnetically activated mines. The downside to this “wonder alloy” is its cost to manufacture (titanium is difficult to grind and work), material costs and its very low hardness and therefore very low edge retention. Most titanium knives (although costing $500.00 - $600.00+ dollars) will be on the Rockwell scale at about 43-45Rc! Far too soft for constant usage.
Despite being prohibited items in most localities (for their ability to be undetectable by metal detectors and therefore are seen by some to be a security risk) come in a few different forms. Forms of crystalline saffire, bonded ceramic compounds and high tech plastics. Saffire and ceramic types have VERY high hardness and therefore possibly the best edge retention available but will tend to be brittle and impossible to sharpen on anything other than diamond sharpening systems. Plastics on the other hand will be quite soft but will be nearly unbreakable and totally rust and stain free, in the literal sense but next to no edge retention to speak of.
Steel compositions will baffle most as they are really only reserved for the engineers and fanatics amongst us, however, this will serve as a guide to the availability of steel types for potential customers.
Point to note: Most steel names or designations are for use in certain countries only. For instance, the Russian 65X13 or French Z60 could be the equivalent to Japanese AUS8 but both have different names. Each country puts their own designations to steel alloys. Another example was the US response to Japanese ATS-34 being 154CM, both nearly identical in every way.
When choosing a knife or tool that is.
For a machete or a heavy-duty usage tool look for a Carbon steel with a hardness on the lower side of 54-58 Rockwell. This will provide a tough tool that will sharpen easily and be able to withstand lots or repeated impacts and stresses.
For a low maintenance skinning, hunting, survival, field, utility, combat knife look for a good stainless steel with a relatively high carbon content like Z60, AUS8, 440C, ATS-34, 154CM etc.
For those that maintain their gear meticulously then folding and general use fixed blades of all types in any carbon or tool steel alloy will serve well.
Be mindful of how you use and look after tools. If you use and abuse and don’t maintain your gear then a large, stainless fixed blade with a 6mm thick blade might be best for you.
If you prefer to clean, oil and store your equipment carefully then you will realise the benefits of such steels as L6 and 1095.
Remember that heat treatment and knife design play a big part in the performance of cutlery. Don’t take it as gospel that any knife made by anyone will be the best knife around simply because it is made out of high grade steel. A knife made by a reputable manufacturer using simple and cheap 420HC and a first rate heat treatment will far outperform a backyard job fashioned out of a high tech alloy like CPM S30V or 440C while using improper heat treatment techniques.
Don’t place much stock into online videos of people destroying knives as part of “reviews” and “testing” to determine a knifes worth. Humans are supposed to be intelligent and capable of making and using tools to live and survive. If you are trying to chop a concrete cinder block in half with a hunting knife then you are not very intelligent to say the least! ANY knife can be broken or destroyed if given enough abuse.
The only thing more important than your knife in a survival situation is your knowledge. If you don’t know how to use a knife properly then having the biggest, toughest space-age alloy knife wont save you anyway as survival knowledge is paramount to your equipment.
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