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The Knife Steel FAQ by Joe Talmadge


Introduction

One thing to keep in mind is that there's more to knife performance than the steel. The blade profile is also important (a tanto format isn't the best choice to skin a deer, for example). But perhaps most important is the heat treatment. A good solid heat treatment on a lesser steel will often result in a blade that outperforms a better steel with inferior heat treatment. Bad heat treatment can cause a stainless steel to lose some of its stainless properties, or cause a tough steel to become brittle, etc. Unfortunately, of the three most important properties (blade profile, steel type, heat treatment), heat treatment is the one that is impossible to assess by eye, and as a result excessive attention is sometimes paid to the other two.

Remember also to keep your particular application in mind. 440A is often scoffed at, but I'd rather have my salt water dive knife made of 440A than L-6. Properly heat treated 5160 is wonderfully tough, but if my application is skinning deer, I'm probably more interested in edge holding ala 52100. And on and on.

Steel Alloys: At its most simple, steel is iron with carbon in it. Other alloys are added to make the steel perform differently. Here are the important steel alloys in alphabetical order, and some sample steels that contain those alloys:

Carbon: Present in all steels, it is the most important hardening element. Also increases the strength of the steel. We usually want knife-grade steel to have >.5% carbon, which makes it "high-carbon" steel. Chromium: Added for wear resistance, hardenability, and (most importantly) for corrosion resistance. A steel with at least 13% chromium is deemed "stainless" steel. Despite the name, all steel can rust if not maintained properly. Manganese: An important element, manganese aids the grain structure, and contributes to hardenability. Also strength & wear resistance. Improves the steel (e.g., deoxidizes) during the steel's manufacturing (hot working and rolling). Present in most cutlery steel except for A-2, L-6, and CPM 420V. Molybdenum: A carbide former, prevents brittleness & maintains the steel's strength at high temperatures. Present in many steels, and air-hardening steels (e.g., A-2, ATS-34) always have 1% or more molybdenum -- molybdenum is what gives those steels the ability to harden in air. Nickel: Used for strength, corrosion resistance, and toughness. Present in L-6 and AUS-6 and AUS-8. Silicon: Contributes to strength. Like manganese, it makes the steel more sound while it's being manufactured. Tungsten: Increases wear resistance. When combined properly with chromium or molybdenum, tungsten will make the steel to be a high-speed steel. The high-speed steel M-2 has a high amount of tungsten. Vanadium: Contributes to wear resistance and hardenability. A carbide former that helps produce fine-grained steel. A number of steels have vanadium, but M-2, Vascowear, and CPM T440V and 420V (in order of increasing amounts) have high amounts of vanadium. BG-42's biggest difference with ATS-34 is the addition of vanadium.

CARBON and alloy steels (non-stainless steels):

These steels are the steels most often forged. Stainless steels can be forged (guys like Sean McWilliams do forge stainless), but it is very difficult. In addition, carbon steels can be differentially tempered, to give a hard edge-holding edge and a tough springy back. Stainless steels are not differentially tempered. Of course, carbon steels will rust faster than stainless steels, to varying degrees. Carbon steels are also often a little bit less of a crap shoot than stainless steels -- I believe all the steels named below are fine performers when heat treated properly.

In the AISI steel designation system, 10xx is carbon steel, any other steels are alloy steels. For example, the 50xx series are chromium steels.

In the SAE designation system, steels with letter designations (e.g., W-2, A-2) are tool steels.

There is an ASM classification system as well, but it isn't seen often in the discussion of cutlery steels, so I'll ignore it for now.

Often, the last numbers in the name of a steel are fairly close to the steel's carbon content. So 1095 is ~.95% carbon. 52100 is ~1.0% carbon. 5160 is ~.60% carbon.

O-1 This is a steel very popular with forgers, as it has the reputation for being "forgiving". It is an excellent steel, that takes and holds an edge superbly, and is very tough. It rusts easily, however. Randall Knives uses O-1, so does Mad Dog.

W-2 Reasonably tough and holds an edge well, due to its .2% vanadium content. Most files are made from W-1, which is the same as W-2 except for the vanadium content (W-1 has no vanadium).

The 10-series -- 1095 (and 1084, 1070, 1060, 1050, etc.) Many of the 10-series steels for cutlery, though 1095 is the most popular for knives. When you go in order from 1095-1050, you generally go from more carbon to less, from better edge holding to less edge holding, and tough to tougher to toughest. As such, you'll see 1060 and 1050, used often for swords. For knives, 1095 is sort of the "standard" carbon steel, not too expensive and performs well. It is reasonably tough and holds an edge very well. It rusts easily. This is a simple steel, which contains only two alloying elements: .95% carbon and .4% manganese. The various kabars are usually 1095 with a black coating.

Carbon V Carbon V is a trademarked term by Cold Steel, and as such is not necessarily one particular kind of steel; rather, it describes whatever steel Cold Steel happens to be using, and there is an indication they do change steels from time to time. Carbon V performs roughly between 1095-ish and O-1-ish, in my opinion, and rusts like O-1 as well. I've heard rumors that Carbon V is O-1 (which I now think is unlikely) or 1095. Numerous industry insiders insist it is 0170-6. Some spark tests done by a rec.knives reader seem to point the finger at 50100-B. Since 50100-B and 0170-6 are the same steel (see below), this is likely the current Carbon V.

0170-6 - 50100-B These are different designations for the same steel: 0170-6 is the steel makers classification, 50100-B is the AISI designation. A good chrome-vanadium steel that is somewhat similar to O-1, but much less expensive. The now-defunct Blackjack made several knives from O170-6, and Carbon V may be 0170-6. 50100 is basically 52100 with about 1/3 the chromium of 52100, and the B in 50100-B indicates that the steel has been modified with vanadium, making this a chrome-vanadium steel.

A-2 An excellent air-hardening tool steel, it is known for its great toughness and good edge holding. As an air-hardening steel, so don't expect it to be differentially tempered. Its outstanding toughness makes it a frequent choice for combat knives. Chris Reeve and Phil Hartsfield both use A-2, and Blackjack made a few models from A-2.

L-6 A band saw steel that is very tough and holds an edge well, but rusts easily. It is, like O-1, a forgiving steel for the forger. If you're willing to put up with the maintenance, this may be one of the very best steels available for cutlery, especially where toughness is desired.

M-2 A "high-speed steel", it can hold its temper even at very high temperatures, and as such is used in industry for high-heat cutting jobs. It is an excellent edge holder. It is tough but not as tough as some of the toughest steels in this section; however, it will still be tougher than the stainless steels and hold an edge better. It rusts easily. Benchmade has started using M-2 in one of their AFCK variations.

5160 A steel popular with forgers, it is extremely popular now and a very high-end steel. It is essentially a simple spring steel with chromium added for hardenability. It has good edge holding, but is known especially for its outstanding toughness (like L-6). Often used for swords (hardened in the low 50s Rc) because of its toughness, and is also used for hard use knives (hardened up near the 60s Rc).

52100 A ball-bearing steel, and as such is only used by forgers. It is similar to 5160 (though it has around 1% carbon vs. 5160 ~.60%), but holds an edge better. It is less tough than 5160 however. It is used often for hunting knives and other knives where the user is willing to trade off a little of 5160's toughness for better edge holding.

D-2 D-2 is sometimes called a "semi-stainless". It has a fairly high chrome content (12%), but not high enough to classify it as stainless. It is more stain resistant than the carbon steels mentioned above, however. It has excellent edge holding, but may be a little less tough than some of the steels mentioned above. And it does not take a beautiful finish. Bob Dozier uses D-2.

Vascowear A very hard-to-find steel, with a high vanadium content. It is extremely difficult to work and very wear-resistant. It is out of production.

"STAINLESS" Steels: Remember that all steels can rust. But the following steels, by virtue of their > 13% chromium, have much more rust resistance than the above steels. I should point out that there doesn't appear to be consensus on what percent of chromium is needed for a steel to be considered stainless. In the cutlery industry, the de-facto standard is 13%, but the ASM Metals Handbooks says "greater than 10%", and other books cite other numbers. In addition, the alloying elements have a strong influence on the amount of chromium needed; lower chromium with the right alloying elements can still have "stainless" performance.

420 Lower carbon content (<.5%) than the 440 series makes this steel extremely soft, and it doesn't hold an edge well. It is used often for diving knives, as it is extremely stain resistant. Also used often for very inexpensive knives. Outside salt water use, it is too soft to be a good choice for a utility knife.

440 A - 440 B - 440C The carbon content (and hardenability) of this stainless steel goes up in order from A (.75%) to B (.9%) to C (1.2%). 440C is an excellent, high-end stainless steel, usually hardened to around 56-58 Rc. All three resist rust well, with 440A being the most rust resistant, and 440C the least. The SOG Seal 2000 is 440A, and Randall uses 440B for their stainless knives. 440C is fairly ubiquitous, and is generally considered the penultimate general-use stainless (with ATS-34 being the ultimate). If your knife is marked with just "440", it is probably the less expensive 440A; if a manufacturer had used the more expensive 440C, he'd want to advertise that. The general feeling is that 440A (and similar steels, see below) is just good enough for everyday use, especially with a good heat treat (we've heard good reports on SOG's 440A heat treat). 440-B is a very solid performer and 440-C is excellent.

425M - 12C27 Both are very similar to 440A. 425M (.5% carbon) is used by Buck knives. 12C27 (.6% carbon) is a Scandanavian steel used often in Finish puukkos and Norwegian knives.

AUS-6 - AUS-8 - AUS-10 (aka 6A 8A 10A) Japanese stainless steels, roughly comparable to 440A (AUS-6, .65% carbon) and 440B (AUS-8, .75% carbon) and 440C (AUS-10, 1.1% carbon). AUS-6 is used by Al Mar. Cold Steel's use of AUS-8 has made it pretty popular, as heat treated by CS it won't hold an edge like ATS-34, but is a bit softer and may be a bit tougher. AUS-10 has roughly the same carbon content as 440C but with slightly less chromium, so it should be a bit less rust resistant but perhaps a bit tougher than 440C. All 3 steels have some vanadium added (which the 440 series lacks), which will improve wear resistance.

GIN-1 aka G-2 A steel with slightly less carbon, slightly more chromium, and much less moly than ATS-34, it is used often by Spyderco. A very good stainless steel.

ATS-34 - 154-CM The hottest high-end stainless right now. 154-CM is the original American version, but for a long time was not manufactured to the high quality standards knifemakers expect, and so is not used often anymore. Late-breaking news is that high-quality 154-CM may again be available. ATS-34 is a Hitachi product that is very, very similar to 154-CM, and is the premier high quality stainless. Normally hardened to around 60 Rc, it holds an edge very well and is tough enough even at that high hardness. Not quite as rust resistant as the 400 series above. Many custom makers use ATS-34, and Spyderco (in their high-end knives) and Benchmade are among the production companies that use it.

ATS-55 Similar to ATS-34, but with the moly removed and some other elements added. Not much is known about this steel yet, but it looks like the intent was to get ATS-34 edge-holding with increased toughness. Since moly is an expensive element useful for high-speed steels, and knife blades do not need to be high speed, removing the moly hopefully drastically decreases the price of the steel while at least retaining ATS-34's performance. Spyderco is using this steel.

BG-42 Bob Loveless announced recently that he's switching from ATS-34 to this steel. Keep an eye out for it, it's bound to catch on. BG-42 is somewhat similar to ATS-34, with two major differences: It has twice as much manganese as ATS-34, and has 1.2% vanadium (ATS-34 has no vanadium), so look for even better edge-holding than ATS-34. Chris Reeves has switched from ATS-34 to BG-42 in his Sebenzas.

CPM T440V - CPM T420V Two steels that hold an edge superbly (better than ATS-34), but it's difficult to get the edge there in the first place. These steels are both high in vanadium. Spyderco offers at least one model in CPM T440V. Custom maker Sean McWilliams is a big fan of 440V, which he forges. Depending on heat treatment, expect to have to work a bit harder to sharpen these steels -- also, don't expect ATS-34 type toughness. 420V is CPM's follow-on to 440V, and with less chromium and almost double the vanadium, is more wear-resistant and may be tougher than 440V.

400 Series Stainless Before Cold Steel switched to AUS-8, many of their stainless products were marketed as being of "400 Series Stainless". Other knife companies are beginning to use the same term. What exactly *is* 400 Series Stainless? I always imagined it was 440-A, but there's nothing to keep a company from using any 4xx steel, like 420 or 425M, and calling it 400 Series Stainless.

NON-STEELS USED BY KNIFEMAKERS

Cobalt - Stellite 6K A flexible material with very good wear resistance, it is practically corrosion resistant. Stellite 6K, sometimes seen in knives, is a cobalt alloy. David Boye uses cobalt for his dive knives.

Titanium Newer titanium alloys can be hardened near 50 Rc, and at that hardness seem to take something approaching a useful edge. It is extremely rust-resistant, and is non-magnetic. Popular as expensive dive knives these days, because the SEALs use it as their knife when working around magnetic-detonated mines. Mission knives uses titanium. Tygrys makes a knife with a steel edge sandwiched by titanium.

znaš možda od kojeg čelika su rađene one armaturne šipke? Imam cijelu hrpu nedaleko od kuće, svih debljina, gradi se zaobilaznica...pa bi probao napravit jedan nož od toga.

Nemam pojma, al na forumu ima pravih eksperata za čelik, pa će valjda oni znat. Mada mi te šipke i ne izgledaju kao nešto od čega bi se da napravit dobar nož. Možda griješim.

Ja mislim da bi trebale biti kvalitetne, ipak moraju držat nekoliko stotina tona, i više , sa stezanjem i stiskanjem zimi i ljeti...ali to sam samo ja

Možda si u pravu, prijatelju. Ja se u to stvarno ne razumim. Te šipke mi izgledaju onako prilično nezahvalne za obradu, ne kažem da je loš čelik.

Ma ja stvarno ne razumijem kako raspoznati koji čelik od kojega...znam u teoriji da su suspenzije kamiona jako viski, 1095 ili onaj pet tisuća i nešto, ali ja sam tu priglup.

Najbolje da pričekamo mariobab-a. On će sigurno imat reć koju pametnu na ovu temu.

Pa čuj, ja sam od armaturne šipke napravio nož-i za silu je dobar-bolji recimo nego nož od bešteka.Ali to se i zove betonsko željezo zato jer nema dovoljan udio ugljika da bi ga se zvalo čelikom.A onda ne ide niti kaljenje.Iako postoje načini da se i to riješi,dodavanje ugljika(cementiranje) i kovanje na ugljenoj prašini-ali pričekajte Karla.Ja sam od šipke iskovao nož-ali Karlo će vam o tome sigurno moći sve reći.Ovakj dio sa dodavanjem ugljika nisam radio.sa drugog foruma je info.

Onda čekamo Karla! Vidio sam neka jako lijepe radove, samo nijedan na nikakvom testu

Neznam je li ovo od klinova za tračnice ili šipke ali takav je princip

klinovi sa tračnica-ima negdje video kako čovjek radi.

dobro ti je Mario rekao, armaturno zeljezo nije dobar materijal za noz jer ima premalo ugljika da bi se mogao zakaliti. od toga mozes raditi, recimo, kljesta za kovanje ili neki zarac i sl.

o ovim cavlima neznam nista osim onoga sto sam procitao na americkim forumima, razne serije imaju razlicite udjele ugljika, tek neke imaju taman da se moze zakaliti ali sve je opet to premalo za ozbiljan noz, medutim, cini mi se vise da je to neka kultura ili sl., pa ih zato rade i gustaju u njima.

predlazem ti da krenes sa nekim federima, turpijama...to ti je zahvalna i dobra stvar i sigurno lako nades.

Kakva je kvaliteta vodilice od motorke u odnosu na feder platu i rašpu?

sad cekamo Legion66, on je iz toga radio neke nozeve i kaze da je dobar celik za noz ali, kazem, radije cujmo njega.

prsten starog kugellagera,zatim list motorne pile i ak toga nemaš federplate je najbolji izbor koji vam se pruža.
iči dublje u materiju je možda pretjerano i nema smisla!
jer tematika je toliko opširna da ne stane u nekoliko knjiga!

Vidim da mi se nož od vodilice pomalo tupi pa se pitam ima li šta bolje, možda je oštrica i pregorila ali sumnjam jel voda nije nikad kipila kad sam polijevao oštricu.
Pitam se bi li ovaj nož od 90kn bolje držao oštricu?

Ova Mora bi definitivno držala oštricu.
Kaj se tiće vodilice od motorke mogu reći da sam napravil više komada noževa od toga i da sam uvijek bil zadovoljan.
Kaj se tiće samog materijala može se naći dosta čistih komada bez hrđe, pa se samim time smanjuje tijek finiširanja noža.
Za onog ko nema mjesta, volje ili mogučnosti za kovanje list od motorke je pravi izbor materijala za izradu noževa.

p.strumf je napisao/la:Vidim da mi se nož od vodilice pomalo tupi pa se pitam ima li šta bolje, možda je oštrica i pregorila ali sumnjam jel voda nije nikad kipila kad sam polijevao oštricu.
Pitam se bi li ovaj nož od 90kn bolje držao oštricu?

moze malo detaljnije pojasnjenje, sto si tocno radio?

Šta sam točno radio sa oštricom? bio je nož u kuhinji nekih tjedan dana pa vidim da nije više oštar kao prije, tupi se otprilike kao neki jeftini nož. Ali trebalo bi još testirati. Veči nož se nije zatupio ni nakon tesanja drveta.

Znači armaturne šipke su mi za alat, za neku nevažnu potrošnu robu, klinove nemam gdje nabaviti- možda dolje u HŽ-u, ali sumnjam da bi dali...

Kako misliš za kaljenje? Je li to isto što i taljenje? Sada sam se izgubio, neznam što je što.

Kako (i kamo) mogu naučiti raspoznavati vrste čelika, na dodir i tako...znam da visokougljični ima jarke iskre kada se brusi, malougljični narančaste, tamne, a npr titanij bijele kao sunce...
Postoji li tako nešto i za ove manje skupine?

Kaljenje je...
Znači prvo se čelik zagrije na visoku temperaturu pa se naglo hladi. Čelik postane tvrd i krhak, izgubi elastičnost...

Taljenje je...

p.strumf je napisao/la: kipila kad sam polijevao oštricu.

Možda je tako kaljeno, poput tradicionalnog načina kaljenja kukrija-vruća se voda polijeva samo po oštrici.

Aha, sada kužim. Znači termička obrada je kaljenje? Ona ojačava ali oduzima elastičnost nožu? E sada mirno spavam =)

Zašto se koji put dogodi da nasred noža nastane pukotina zbog loše temperaturne obrade?

Strider je napisao/la: zbog loše temperaturne obrade?

Da

moko je napisao/la:prsten starog kugellagera

...je u pravilu 52100 celik. Karlo je radio s njime.
Imam negdje nekoliko starih lezajeva pa mozda pokusam i ja napraviti nesto ako me kovanje privuce (za sada se opirem jer bi se zarazio sigurno hehehe)

p.strumf je napisao/la:Šta sam točno radio sa oštricom? bio je nož u kuhinji nekih tjedan dana pa vidim da nije više oštar kao prije, tupi se otprilike kao neki jeftini nož.

A sta ocekujes od njega ?? Ako je bio u rukama zene onda i da je vrhunski celik sa vrhunski napravljenom TO bi otupio, dokazano bezbroj puta =)

Strider je napisao/la:Aha, sada kužim. Znači termička obrada je kaljenje?

Toplinska obrada je niz procesa... a obuhvaca normalizaciju, kaljenje, popustanje...ima toga jos ali ovo je najbitnije.

Strider je napisao/la: Ona ojačava ali oduzima elastičnost nožu? E sada mirno spavam =)

Kaljenjem ojacavas (dobija tvrdocu ali je krhak kao staklo) noz a popustanjem smanjujes tu tvrdocu noza i vracas mu nesto malo elasticnosti (u ledja) kako noz ne bi pukao lako prilikom koristenja. Tako dobijes tvrdu ostricu (zbog rezanja) a elasticnija ledja zbog elasticnosti, tj plasticnosti

Mislim da onaj popis i opis celika nema previse smisla jer su kod nas u pincipu nedobavljivi (osim ako se ne narucuje iz vana)
Najdostupniji su nam:
perni celici (plocaste i spiralne opruge),
onaj 52100 celik (lezajevi)
alatni celici (sajbe od cirkulara - nozevi od kosilica...)
vodilice od motorki (ali onih starih jer se danas nove rade od seta limova koji su zanitnani a unutra je suplja)
gateri sa starih pilana....
O ovome je vec bilo dosta rijeci na forumu.

Sto se tice nehrdjajucih celika mislim da je rijetko tko od hobby/amaterskih knifemakera kod nas uopce sposoban nabaviti kvalitetan celik i pravilno ga toplinski obraditi. Uglavnom su to poluproizvodi i pokusaji improvizacije.

Potpisujem.

LEGION66 je napisao/la:Ova Mora bi definitivno držala oštricu.
Kaj se tiće vodilice od motorke mogu reći da sam napravil više komada noževa od toga i da sam uvijek bil zadovoljan.
Kaj se tiće samog materijala može se naći dosta čistih komada bez hrđe, pa se samim time smanjuje tijek finiširanja noža.
Za onog ko nema mjesta, volje ili mogučnosti za kovanje list od motorke je pravi izbor materijala za izradu noževa.

Imam drugu vodilicu koja je sastavljena od 3 dijela. Mogu li se razdvojiti ti dijelovi?

Da mogu se razdvojiti, al to baš i nije neki materijal za nož, bolje nabavi stare listove.

Dobro bi mi došao tako uski materijal. Kako je razdvojiti? nabiti šarafciger unutra i bude išlo?

Neznam dali mogiu nabaviti staru vodilicu.

Mani se čorava posla, ak nabiješ šarafciger između vanjskih dijelova, prije ćeš strgat šarafciger nego ih razdvojit jer su točkasto zavarene. Odi se rađe zaleti na Jakuševac i tam si nađeš dobrih listova za par kuna.

Razdvojio sam ju sa šarafcigerom bez problema. Ali taj sloj čelika koji se odvajao je lagano svinut, te tamo gdje su nitne bile je istrgan čelik tako da su duboke udubine.