同樣大小的刀用 頂級的鋼要300到500，而一般的碳鋼就5到20
Ultimately, the different types of steel used in knife blades each exhibit varying degrees of these five key properties:
Hardness
Hardness is the ability to resist deforming when subject to stress and applied forces. Hardness in knife steels is often referred to as strength and is generally measured using the Rockwell C scale (aka “HRC”).
Toughness
Toughness is the ability to resist damage like cracks or chips when being used in heavy duty applications. This also defines the steel’s ability to flex without breaking. Chipping is a knife’s worst enemy and never easy to fix. Note that the stronger or harder the steel the less tough it will likely be. Also, the measurement of toughness is less standardized as hardness.
Wear Resistance
Wear resistance is the steel’s ability to withstand damage from both abrasive and adhesive wear. Abrasive wear comes from softer surfaces coming in contact with rougher ones. Adhesive wear occurs when debris is dislodged from one surface and attaches to the other. Wear resistance generally correlates with the steel’s hardness but is also heavily influenced by the specific chemistry of the steel. In steels of equal hardness, the steel with larger carbides (think microscopic, hard, wear resistant particles) will typically resist wear better.
Corrosion Resistance
Corrosion resistance is the ability to resist corrosion such as rust caused by external elements like humidity, moisture and salt. Note that a high resistance to corrosion does involve a sacrifice in the overall edge performance.
Edge Retention
Edge Retention represents how long the blade will retain its sharpness when subject to periods of use. It’s what everyone talks about these days but unfortunately the measurement of edge retention lacks any defined set of standards and so much of the data is subjective. For me, edge retention is a combination of wear resistance and an edge that resists deformation.
Unfortunately the “best knife steel” is not simply a case of maximizing each of the properties above….it’s a trade off. The biggest trade off is balancing strength or hardness with toughness. Some blades can be made to be exceptionally hard but will chip or crack if you drop them onto a hard surface. Conversely a blade can be extremely tough and able to bend but will struggle to hold it’s edge. Also note that the term ‘stainless steel‘ is generally misleading as all types of steel will show some kind of discoloration if left exposed to the elements for long enough. By knowing how you plan to use the knife you will generally be able to determine the best steel for your situation.
Common Knife Steel Types
The most common blade steel types generally fall into the following categories:
- Tool Steel – primarily hard steel alloys used in cutting tools. Some popular steels in this group include D2, O1 and Crucible’s CPM series (i.e. CPM 3V) plus more advanced high speed steels like M4.
- Carbon Steel – generally made for rough use where toughness and durability is important. Common in survival knives and machetes. They take a sharp edge and are relatively easy to re-sharpen. The trade-off is being more prone to corrosion given the low chromium content. The most popular carbon knife steel is 1095.
- Stainless Steel – basically carbon steel with added chromium to resist corrosion and other elements which increase performance levels but usually at the expense of inferior toughness. Easily the most popular category today and includes the 400, 154CM, AUS, VG, CTS, MoV, Sandvik and Crucible SxxV series of steels. Note that to qualify as a true stainless steel there must be at least 13% chromium.
Today’s popular knife steels
Below are the most common steels found in knife blades today. Yes, technically there are “better” steels out there (CPM-125V, CPM-10V, K294 to name a few) but these are extremely rare in the marketplace. Don’t get too carried away with the perceived rankings, it’s not an exact science and this is simply my way of bucketing the steels into general performance categories based on a variety of factors.
CPM S90VThe ultimate in wear resistance and edge retention comes with Crucible’s CPM S90V steel. As you’d expect the carbon content is very high but the secret here is the extreme quantities of vanadium, almost three times that found in Elmax or S30V. Yes it’s ridiculously expensive, and yes it requires the patience of a saint to sharpen but nothing holds an edge or withstands abrasion quite like CPM S90V. One of the hottest CPM S90V blade’s right now is the Benchmade 940-1 with exceptional performance. Hold on to your hats though folks, because there’s a new contender gaining traction in the marketplace and that is S110V. More on that coming soon…
M390M390 is one of the new super steels on the block, manufactured by Bohler-Uddeholm (result of merger of Austrian Bohler and Swedish Uddeholm). It uses third generation powder metal technology and developed for knife blades requiring excellent corrosion resistance and very high hardness for excellent wear resistance. Chromium, molybdenum, vanadium, and tungsten are added to promote sharpness and outstanding edge retention. Unlike ZDP-189 most carbides are formed by vanadium and molybdenum, leaving more ‘free chromium’ to fight corrosion. M390 hardens to 60-62 HRC. Bohler calls this steel “Microclean” and it can be polished to achieve a true mirror. Moderately difficult to sharpen, but won’t take you as long as with S90V. Benchmade’s 581 Barrage is an affordable example of M390 performing at its best.
ZDP-189ZDP-189 by Hitachi is another of the newer super steels containing huge quantities of carbon and chromium that result in ridiculous levels of hardness. ZDP-189 averages around 64 HRC but some knifemakers are able to achieve upwards of 66 HRC. Of course with those levels of hardness you can expect superb edge retention but at the cost of extreme difficulty in sharpening. With a chromium content of around 20% you’d expect it to be immune to corrosion right? Wrong. The massive amount of carbon in ZDP-189 effectively ‘pairs up’ with the chromium to form carbides which leaves less ‘free chromium’ to battle corrosion. So, while it’s both harder and more wear resistant than S30V it’s more prone to corrosion. Spyderco’s Dragonfly 2 is a good example.
ElmaxEuropean Uddeholm (now Bohler-Uddeholm) introduced Elmax which is a high chromium-vanadium-molybdenum alloyed powdered steel with extremely high wear and corrosion resistance. Elmax is stainless but acts in many ways like a carbon steel. You get superb edge holding and relatively easy sharpening while maintaining a healthy resistance to rust. The ‘best all round’ knife steel? Perhaps. What’s great to see is that Bohler-Uddeholm sure is giving Crucible a run for their money these days. Great example of a superb Elmax blade is found on the popular ZT 0562.
CPM-20CVCPM-20CV is Crucible’s version of Bohler’s popular M390 steel which also influenced Carpenter to copycat with CTS-204P. As a Powder Metallurgy (PM) tool steel, you get a combination of impressive wear resistance and edge retention plus the added benefit of being highly corrosion resistant due to high levels of chromium. It’s still fairly new in the market but makers like Benchmade are already using CPM-20CV in newer models like their 556-1 Griptilian. In fact, Benchmade claim their M390 is marginally tougher but 20CV has better edge retention.
CTS-XHPCTS-XHP from US based Carpenter is another relatively new knife steel that has very good edge retention and hardens to about 61 HRC. This is yet another powder metallurgy creation where Carpenter’s technicians have developed an extremely fine powder grain that results in excellent performance. Slightly better edge retention than S30V and but a little more work required in the sharpening process. Think of CTS-XHP as a more corrosion resistant form of D2 steel with marginally superior edge retention. Like D2, however, it’s not easy to sharpen and can be brittle (prone to chipping).
CPM M4A high performance tool steel which excels at toughness and arguably holds and edge better than any other carbon steel. Like all CPM steels, CPM M4 is created using Crucible’s patented Crucible Particle Metallurgy process, which provides an extremely homogeneous, stable and grindable product compared to the traditional processes. CPM M4 provides superbly balances levels of abrasion resistance and toughness through high doses of molybdenum (hence the “M”), vanadium and tungsten together with reasonably high levels of carbon. It can be hardened to around 62-64 HRC but note M4 is a carbon steel is not considered stainless with relatively low levels of chromium. So, while this is one of the best steels around for cutting, it has to be properly cared for and may develop a patina over time. Some manufacturers have resorted to coatings which do help but note they won’t last forever. Easy to sharpen?…erm, no.
CPM S35VNIn 2009, Crucible and Chris Reeve introduced an ever so slightly superior version of their excellent S30V steel and named it S35VN. By using a much finer grain structure and adding small quantities of niobium (hence the “N”) they were able to make the outstanding S30V easier to machine while improving toughness and ability to sharpen. In the real world, however you will find the two near-indistinguishable. Many would argue this is the ultimate in ‘mainstream’ knife steels and you would struggle to find any steel with better edge retention, toughness and stain resistance for the money.
CPM S30VMade by US based Crucible, CPM S30V (often simply referred to as S30V) steel has excellent edge retention and resists rust effortlessly. It was designed in the US and is typically used for the high-end premium pocket knives and expensive kitchen cutlery. The introduction of vanadium carbides brings extreme hardness into the steel alloy matrix. Dollar for dollar, this is generally regarded as one of the finest knife blade steels with the optimal balance of edge retention, hardness and toughness. Note S30V now has a slightly better looking brother in S35VN which is distinctly similar but easier for manufacturers to work with thanks to niobium. Still, S30V is pretty common these days and one of our favorites.
154CMA relatively hard steel which is considered an upgraded version of 440C through the addition of Molybdenum. This achieves superior edge holding compared to 440C while retaining similar excellent levels of corrosion resistance despite having less Chromium. It has decent toughness good enough for most uses and holds an edge well. Not too difficult to sharpen with the right equipment. You’ll find a lot of quality pocket knives from top manufacturers like Benchmade using 154CM steel. You may also see CPM 154 which is a powder version of the same alloy produced much differently using Crucible Particle Metallurgy. The CPM process makes finer carbide particles resulting in a slightly superior steel with better edge retention … but whether the average user can tell the difference is arguable.
ATS-34This steel can be thought of as the Japanese equivalent to the US made 154CM. Accordingly, it has very similar properties and characteristics to the 154CM and in general represents a high quality steel which has become very popular with knife makers. ATS-34 has great edge retention but is actually a little less rust resistant than the lower-range 440C steel.
D2D2 steel is a tool steel often referred to as “semi-stainless” as it falls just short of the required amount of chromium (13%) to qualify as full stainless yet it still provides a good amount of resistance to corrosion. On the flip side D2 steel is much harder than other steels in this category such as 154CM or ATS-34 and as a result holds its edge a little better. That said, it’s not as tough as many other steels and exponentially tougher to sharpen. In fact, you really need to be a master-sharpener to get a fine edge on D2.
VG-10The VG-10 steel is very similar to 154CM and ATS-34 with slightly more chromium for enhanced corrosion resistance but also contains vanadium which makes it marginally tougher than these two. It originated not too long ago from Japan and has been slowly introduced into the American market by respect knife makers like Spyderco. It’s really hard and can get extremely sharp but also somewhat brittle so prone to chipping.
H1H1 steel from Japan’s Myodo Metals is basically the ultimate in corrosion resistance and essentially does not rust. The epitome of true stainless steel. Naturally, this comes at a price and that price is edge retention which is relatively poor. So, while excellent for diving it’s a non-starter for most EDC use. Very expensive stuff.
N680N680 steel contains about 0.20% nitrogen and over 17% chromium making it extremely corrosion resistant. If your blade will be in frequent contact with salt water for example then this is the steel for you. It’s also a fine grained steel that can take a very fine edge. Consider it a cheaper alternative to H1 steel with decent edge retention but it won’t hold an edge as long as say, 154CM.
440COnce considered the high-end in US knife steels, 440C is a good all-round steel that has now been overshadowed by many of the newer super-steels on the block. This is a stainless steel commonly used on many mass-manufactured pocket knives and represents a solid affordable all-round choice. It’s reasonably tough and wear resistant but it really excels at stain resistance. Holds an edge better than it’s 400-series counterpart 420HC but at the expense of some corrosion resistance. The 440C blades can be sharpened relatively easily. It has the highest levels of carbon and chromium in this group.
AUS-8AUS-8 steel is Japanese made and extremely similar to 440B steel which is slightly more resistant to rust and corrosion than 440C but less hard. It’s also similarly tough but may not hold its edge as well as some of the more premium steels which carry a greater degree of carbon. Remember, more carbon means more hardness and edge holding. Real easy to sharpen and takes a razor edge.
CTS-BD1Created at Spyderco’s request, CTS-BD1 is a vacuum-melted stainless steel from US based Carpenter that is often likened to AUS-8 and 8Cr13MoV with many putting it slightly ahead of those two based on superior edge holding. With slightly more chromium it also achieves better corrosion resistance. CTS-BD1 has mid-sized chromium carbides (hard, wear resisting particles) it takes an edge relatively easily but not on par with the wear resistance of high carbide steels like 154CM.
8Cr13MoVThe MoV (or Cr) series of steels originate from China and comparable to AUS-8 but containing slightly higher carbon content. You typically get great value for money with this steel and good manufacturers like Spyderco have mastered the heat treatment process to bring out its best.
1428CNThe 14C28N stainless steel from Swedish manufacturer Sandvik is considered an upgrade to their 13C26 described below. In fact, Kershaw asked Sandvik to make their 13C26 steel more resistant to corrosion and the result was 14C28N. In the lab you’ll find slightly more chromium and less carbon in the 14C28N but the real secret is the addition of Nitrogen which promotes corrosion resistance. Overall a very impressive mid-range steel that can be made extremely sharp. Quite possibly the best steel you’ll find on a sub-$30 production knife.
440AVery much like 420HC but with slightly more carbon which results in enhanced levels of wear resistance and edge retention but suffers from weaker anti-corrosion properties.
420HCGenerally considered the king of the 420 steels, 420HC is similar to 420 steel but with increased levels of carbon (HC stands for High Carbon) which makes the steel harder. Still considered a lower-mid range steel but the more competent manufacturers (e.g. Buck) can really bring out the best in this affordable steel using quality heat treatments. That results in better edge retention and resistance to corrosion. In fact, this is one of the most corrosion resistant steels out there, despite it’s low cost.
13C26This is Sandvik’s version of the AEB-L steel, originally developed for razor blades. Close comparison to 440A steel with a higher carbon to chromium ratio making it generally a little harder and wearable at the expense of corrosion resistance. Still, in real world applications it’s difficult to tell them apart and they tend to perform very similarly. Sandvik later came out with 14C28N which is a slightly improved version of 13C26.
1095This is the most popular 10-series standard carbon steel (about 1% carbon) with low corrosion resistance and average edge retention properties. Why would you want 1095 steel? The appeal here is 1095 is a tough steel that’s resistant to chipping, it’s easy to sharpen, takes a crazy sharp edge and is inexpensive to produce. This makes it desirable for larger heavy duty fixed blades and survival knives which are going to be subject to more abuse than your typical EDC. Many manufacturers will coat their 1095 knives to delay the onset of any corrosion but a simple oil treatment will do the trick.
420JThe 420 steel is on the lower end of the quality spectrum but still perfectly fine for general use applications. It has a relatively low carbon content (usually less than 0.5%) which makes for a softer blade and as a result will tend to lose it’s edge quicker than higher end steels. Blades made from 420 steel will rapidly lose their sharp edge over a relatively short time period. That said, it’s typically tough with high flexibility and extremely stain resistant but it is not particularly resistant to wear and tear. As you would expect, knives made from this type of steel are generally low priced, mass produced items.
AUS-6Japanese made equivalent to the 420 series steel. A soft steel that’s generally low quality with relatively little carbon content but it resists corrosion reasonably well.
Knife Steel Performance Charts
Here are my rankings for edge retention, corrosion resistance, Rockwell hardness and wear resistance.
