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When choosing a high-quality folding knife, you should pay special attention to the steel used for the blade.Steel is really the essence of a blade, and the performance of a knife depends on the steel.The essence of steel is an iron alloy containing carbon, which is also rich in other elements to improve certain properties and adapt to different user needs.

In the knife industry, different types of steel have different added elements, and different ways of rolling and heat treatment are used to make blades.For details on these elements, please refer to our knife making steel composition chart.

* in the end, the steel used in these knives is graded according to the following five key properties.

A, hardness

Hardness refers to the ability to resist deformation when subjected to external pressure.The hardness of the tool usually refers to the strength, generally to use HRC (rockwell hardness) to measure.

Second, the toughness

Toughness is the ability to withstand damage such as breaking when used in heavy duty applications.Or the ability of steel to bend without breaking.Rupture is a big damage to a knife and very difficult to repair.It should be noted that the harder a knife is, the less toughness it will have.Of course, the measurement of toughness is not as standardized as hardness.

Wear resistance

Wear resistance is the ability of steel to withstand abrasion and adhesive wear.Abrasion results from contact between a softer surface and a rougher surface.Adhesive wear is formed when debris is transferred from one surface to another.Wear resistance is generally related to the hardness of the steel, but is also largely influenced by the specific chemicals in the steel.In the same hardness of steel, the larger the carbide content of steel particularly wear - resistant.

4. Corrosion resistance

Corrosion resistance refers to the ability to resist corrosion, such as corrosion caused by moisture, moisture, salt and other factors.Note that high corrosion resistance does come at the cost of reducing the sharpness of the blade.

Five, sharp maintenance degree

Sharpness retention is how sharp a knife can be when it is used over a period of time.This is an area that people care about a lot these days, but unfortunately there is a lack of a clear set of criteria for measuring sharpness retention, and most of the data is subjective.In my opinion, sharpness retention is a combination of wear resistance and the ability of the blade to resist deformation.

Unfortunately, * good knife steel is more than just a matter of making each of these features * big...That's just one aspect.* good is achieving a balance between strength, hardness and toughness.Some blades are made to be extremely hard, but if you stab them into a very hard surface, they break or break.On the contrary, a knife is very tough and can bend but its edges are not hard enough.Also note that people are often misled by the name "stainless steel," and that any type of steel exposed to air for a long enough period of time will fade a bit.How do you plan to use your knife, and what kind of steel will you choose according to your situation

Common tool type of steel

* common types of steel include the following:

1.Tool steel - in cutting tools * hard steel.The popular steels in this group mainly include D2, O1 and CPM series, plus more advanced super cut steels like M4.

2. Carbon steel -- generally rough, used where toughness and durability are especially required.Used in lifesaving knives and machetes.It has a sharp edge and is relatively easy to polish.The trade-off is that the chromium content is low and prone to corrosion.* the popular carbon steel is 1095

3. Stainless steel -- basic carbon steel chromium is added to make it resistant to corrosion, other elements are added to improve its performance, but at the cost of reducing toughness.Today's popular types include * 400154 CN, AUS, VG, MoV, Sandvik and CrucibleSxxV series.Note that true stainless steel contains at least 13% chromium.

Now * popular for knife making steel

The following is a list of knife making steels commonly used today. Yes, technically there are better steels (cpm-125v, cpm-10v,K294, etc.) but these are very rare on the market.Don't get bogged down in grading. It's not an exact science. It's simply my way of categorizing steel according to its properties, based on one factor or another.

1. Super type

1, CPMS90V

CPMS90V steel from Crucible offers high wear resistance and sharpness retention.You might think it's very high in carbon, but the secret here is a lot of vanadium, about three times the content of Elmax or S30V.Yes, it's ridiculously expensive and takes a lot of patience to grind, but no other steel is more resistant to abrasion than CPMS90V.The CPMS90V blade is currently available as a Benchmade (*) 940-1 with superior performance.There is another emerging competitiveness that is about to sweep the market, and that is S110V...

2, M390

The M390 is a super steel being sold on the market and is produced by bohler-uddeholm.(formed by the merger of Bohler of Austria and Uddeholm of Sweden). It USES third-generation powder metal technology, and knife making requires superior corrosion resistance and very high hardness to ensure wear resistance.Add chromium, molybdenum, vanadium, and tungsten to improve sharpness and superior sharpness retention.Unlike the zdp-189, most of the carbide is formed from vanadium and molybdenum, leaving a separate element called free chromium, which is used to resist corrosion.The hardness of M390 reaches 60-62hrc.Bohler calls the steel "Microclean" and it can be polished to create a mirror-like effect.Grinding is medium, but not as hard as the S90V.Benchmade (*) 581Barrage is an outstanding example of a good performance of M390.

3, ZDP - 189

The zdp-189, made by Hitachi, is another new type of super steel that contains large amounts of carbon and chromium, making it incredibly hard.The zdp-189 is about 64HRC hard, but some knife manufacturers can make it up to 66HRC hard.Of course, with this super hardness, you can achieve excellent sharpness retention, but at the cost of increasing the grinding difficulty.The chromium content is about 20%. Do you think it will be resistant to corrosion?And it isn't.The large amount of carbon in the zdp-189 is actually paired with chromium to form carbide, so free chromium cannot be used to fight corrosion.Therefore, although it is harder and more resistant to wear than S30V, it is also more prone to corrosion.Spyderco's dragonfly2 is a good example.

4, Elmax

Uddeholm of Europe produces the Elmax, a high-content alloy of chromium-vanadum-molybdenum powdered steel with excellent wear resistance and corrosion resistance. The Elmax is stainless steel, but in some ways behaves like carbon steel.It has excellent edge strength and is relatively easy to polish. It also has good rust resistance.Is this * full range of tool steel?Perhaps.It is good to see that bohler-uddeholm now poses a threat to Crucible.The ZTrexford0801 is an excellent example of an Elmax blade.

5, CPM20CV

CPM20CV is a clone of Bohler's popular M390.Craftsman imitations of cts-204p are also affected.As powder metallurgy tool steel, it combines superior wear resistance and sharp retention, plus its high chromium content and corrosion resistance.It is still quite new on the market, but manufacturers like Benchmade (butterfly) have used the cpm-20v to make new cutters like their 556-1griptilian. In fact, Benchmade (butterfly) claims that their M390 is slightly tougher, but the 20CV maintains a sharper grip.

Second, high quality

1, CTS - XHP

America's cts-xhp is also a relatively new type of steel, with good sharpness retention and a hardness of about 61HRC.This is another powder metallurgy invention, where Carpenter's technicians extracted excellent powdery particles to achieve excellent performance.The sharpness retention is a little better than S30V, but it takes a little more work in the polishing process.Cts-xhp is generally considered to be more resistant to corrosion than D2 steel with excellent sharp retention.And unlike D2 steel, it is not easy to polish and break.ColdSteel has replaced most of its folding knives with this kind of steel. It has to be said that ColdSteel is a pioneer in the large-scale adoption of new steel and new materials in the cutting tool industry.

2, CPMM4

A tool steel of higher performance, good toughness, arguably better than any other carbon steel.Like all CPM steels, CPMM4 USES Crucible's proprietary technology, the Crucible particle metallurgy process (abbreviated CPM), which produces a highly uniform, stable and milled product compared to the traditional process.CPMM4 greatly balances wear resistance and toughness by adding large doses of molybdenum, vanadium, tungsten and, of course, a lot of carbon.The hardness is approximately 62-64HRC, but it should be noted that the M4 is a carbon steel with a relatively low chromium content, not stainless steel.So even though it's one of the best pieces of steel to cut, it has to be carefully maintained, and it can rust over time. Some manufacturers use surface coatings to prevent rust, but that's not a long-term solution.Is it easy to polish?...Well, no.

3, CPMS35VN

In 2009, Crucible and ChrisReeve produced a slightly superior steel type S35VN than their premium steel S30V.It is made by using a finer grain structure and adding a small amount of niobium, which makes the excellent S3OV easier to cut and improves its toughness, making it easier to grind.In real life, however, you can hardly tell the difference.A lot of people think this is the limit of 'mainstream' knife steel, and it's hard to buy a steel that is superior to it in terms of sharpness retention, toughness and rust resistance at this price.

4, CPMS30V

Made by us company Crucible, CPM30V steel offers exceptional sharpness retention and corrosion resistance.It was designed in the United States to make high-end pocket knives and expensive knives and forks.The addition of vanadium carbide greatly increased the hardness of the alloy matrix.You get what you pay for. Basically, I think it is one of the * good knife making steels, with a good balance of sharpness, hardness and toughness.Note that the S30V also has an excellent sibling, the S35VN, which is similar in shape but easier to make thanks to niobium.But S30V is still quite common today and is still one of our * loves.

3. High-end style

1, 154 cm

Relatively high hardness, it is generally considered to be 440C after adding molybdenum elements upgrade version.Compared with 440C, it has superior sharpness retention. Although the content of chromium is slightly lower, it still retains excellent corrosion resistance.It is resilient enough for most USES.It is not difficult to polish a tool if it is used properly.You will find that many Benchmade knives are made from 154CM steel.Unlike other alloys produced using the same Crucible particle metallurgy process, the CPM process optimizes the carbide particles to produce this slightly sharper retaining steel...But whether every user can tell their differences is not always the case.

2. ATS - 34

It is widely believed that this type of steel from Japan is equivalent to 154CM steel made in the United States.In fact, it has very similar properties to 154CM, and generally speaking, it is very popular among tool makers as a representative of high-quality steel.The ats-34 has excellent sharpness retention, but it is actually less resistant to corrosion than the lower grade 440C steel.

3. The D2

Steel D2 is a tool steel and is often referred to as' half stainless 'because it has a low chromium content compared to full stainless steel, which requires a 13% chromium content. However, it is resistant to corrosion.On the other hand, steel D2 is much stiffer than other types of steel in this group, such as 154CM and ats-34, and the edges will be better maintained.That is to say, it is not as tough as many other steels and is much harder to polish.In fact, if you want to have a sharp D2 steel knife, you really need to be a good knife sharpener.

4. VG - 10

The vg-10 steel is very similar to the 154CM, ats-34 steel, with a higher chromium content, which improves corrosion resistance, and vanadium, which makes it more flexible than either.It originated in Japan and was not produced for a long time. It is used in almost all Damascus kitchen knives handmade by Japanese knifemakers, including those made by the Japanese for the German shuang li.Therefore, the high-end kitchen knife made in Japan is much more cost-effective than shuang li.Now VG - 10 slowly by the knife company Spyderco (spider) into the American market, it is really very hard, need special polishing, also a little fragile.

5. H1

H1 steel is produced from Japan MyodoMetals company, basically is anti-corrosion ability * good, basically does not rust, is the typical representative of stainless steel.Sure, the price is pretty high, but the sharpness is not.Therefore, it is very suitable for making diving gear.Very expensive material.

6. N680

N680 steel, with nitrogen content of 0.02% and chromium content of 17%, is therefore quite resistant to corrosion.For example, if your blades are exposed to salt water a lot, this steel is for you.It is also a fine crystalline steel, so the edges are very sharp.Think of it as a slightly cheaper alternative to H1, with proper sharpness retention, just not as strong as 154CM retention.

4. Medium

1.440 C

Once considered a good steel with all its advantages, the 440C, made in the United States, is now dwarfed by many of the new products on the market.

This is a kind of stainless steel, which is used in many small folding knives produced in large quantities. It is a reliable, affordable and high quality choice.It is quite tough, resistant to wear and corrosion.The 440C blade is relatively easy to grind.In this group, it is high in carbon and chromium.

2. The AUS - 8

AUS - 8 steel is made in Japan. It is very similar to 440B steel. Compared with 440C steel, it is rustproof and corrosion resistant, but its hardness is slightly worse.The toughness is similar, but not as sharp as some of the more expensive steels that contain carbon.Keep in mind that the higher the carbon content, the harder and sharper the steel.Very easy to polish and keep sharp.

3. The CTS - BD1

Manufactured at the request of ColdSteel, the cts-bd1 is a stainless steel smelted in a vacuum in the United States. Based on Carpenter, it is often compared to the AUS - 8 and 8Cr13MoV, and many would put it ahead of both because of its superior edge bearing.Because of the slightly higher chromium content, it is more resistant to corrosion.As a fine crystal, low-carbon steel, it is relatively easy to keep the edge shape, but not for as long as high-carbon steel such as the vg-10.

4.8 Cr13MoV

The MoV series of steel produced in China is comparable to AUS - 8, but slightly higher in carbon and cheaper.Manufacturers like Spydecro (spider) use the steel in their cheap folding knives.

5.14 C28N

The 14C28N stainless steel is produced by the Swedish company Sandvik and is an upgraded version of their 13C26.In fact, Kershaw (tool brand) asked Sandvik to optimize 13C26 steel to make it more resistant to corrosion, resulting in the production of 14C28N.In the lab you'll find that 14C28N increases nitrogen and decreases carbon, but the real secret is that adding nitrogen increases corrosion resistance.All in all, a shocking grade of heavy steel should be able to make a very sharp knife.Chances are you got a good steel knife for less than $30.

Fifth, medium and low grade

1.440 A

Much like 420HC but with more carbon, it improves wear resistance and sharpness retention, but reduces corrosion resistance.

2.420 the HC

Generally regarded as 420 series steel *, 420HC is similar to 420 steel, which increases the carbon content and increases the steel hardness.Although it is listed in the middle and lower grades, some competent manufacturers can still use heat treatment technology to make this cheap steel to achieve great value, so that its sharp retention and corrosion resistance to achieve excellent.In fact, although it is cheap, it is one of the most corrosion-resistant steels.

3.13 C26

This is a copy of the aeb-l steel made by Sandvik, originally for razors.Compared to 440A, the carbon content is higher and the chromium content is lower, so the hardness and wear resistance are increased, but the cost is reduced corrosion resistance.In practice, their performance is very similar, difficult to distinguish.Sandvik later produced 14C28N, which was slightly better than 13C26.

4.1095

This is * the popular 10- series standard carbon steel with weak corrosion resistance and moderate sharpness retention.So why do you still want 1095 steel?The answer is here, 1095 steel is a tough steel, not easy to break, easy to polish, extremely sharp edge and low production cost.As a result, it is ideal for making larger heavy duty blades and survival knives, rather than being abused for carrying knives on a daily basis.Many manufacturers sheath their 1095 knives to prevent rust, but the easy way is to coat the surface with oil.

6. Low-end style

1, 420 & 420 j

420 steel is at the lower end of the quality scale, but it is adequate for general use.Its relatively low carbon content makes it suitable for softer blades, which tend to have blunt edges compared with high-end steel.A blade made of 420 steel will soon become dull. That is to say, it is flexible and rust-resistant, but it is generally not resistant to wear and tear.As you can imagine, knives made of this steel are generally cheap and mass-produced.

2, AUS - 6

Made in Japan, equivalent to 420 series steel.A mild steel, not high quality, relatively low carbon content, but very good corrosion resistance.

Performance chart of knife making steel

The following is the order of sharpness retention, corrosion resistance, rockwell hardness, and wear resistance of steel:

Knife - making steel sharpness retention index

Corrosion resistance index of knife - making steel

Hardness of knife steel

Wear resistance index of knife - making steel

What is CPM steel?

CPM stands for Crucible particle metallurgy, a process used to make high-quality tool steel.CrucibleIndustries, an American * manufacturer of CPM steel, pours a metal solution into a small nozzle and USES a high-pressure gas to eject it into a small droplet.The droplets are cooled, solidified, and formed into a powder, which is then bonded and compacted by thermal isocompression.The success lies in the HIP (thermal isobaric) process, which ensures that the composition of each particle is uniform.This also improves the toughness and wear resistance of the steel.

Austenitic and martensitic steel (austenitic, martensitic)

The high content of nickel in austenitic steel makes it less magnetic and relatively soft, making it unsuitable for cutting.Its advantages are its toughness and superior corrosion resistance, as well as its high chromium content, so it is * suitable for making knives and forks, spoons, kitchen sinks and the like.Martensitic steel has less chromium and is easy to rust, but very little nickel, so it is magnetic.What really distinguishes martensitic steel is its high carbon content, which makes it harder and ideal for cutting tools.Steel manufacturers are able to convert austenite to martensitic steel by rapid cooling.

How about Damascus steel?

Damascus steel is made in India, Pakistan and other middle eastern countries, and its production dates back to ancient times before Christ.From the beginning, two different types of steel were welded together. There are many myths about the strength and energy of Damascus steel. Today, it is widely welcomed for its beautiful appearance.Mostly for collection.

Other consideration

Remember, steel is not everything.People who buy knives should be careful not to go for * perfect steel, because steel is not a factor that affects tool performance.Steel analysis has become a science, don't be easily confused by statistics.Keep in mind that blades made from the fine or high-end steel listed above are not necessarily better than knives made from inferior steel.

For example, ColdSteel (ColdSteel company), their cts-xhp, cts-bd1, AUS - 8A steel folding knife, in the United States to do * the key process -- steel heat treatment, the Taiwan plant is only responsible for other processes.Hush -- this is the secret of high cost performance of cold steel knives.

In fact, all modern steel is good enough for most users, and more attention is being paid to other aspects of the penknife, such as the handle and other features.