What is D2 Steel?
D2 steel is a die type of steel, evidenced by the letter D in its name. D2 is an air-hardening, high carbon steel, high chromium steel and has one of the highest levels of carbon among tool steel alloys.
Is D2 Steel Stainless?
However, D2 steel is not categorized as stainless steel because it has a chromium composition of 11.5 to 12%, which does not meet the 13% chromium content to make it stainless. Because of this, D2 tool steel is referred to as semi-stainless tool steel.
In addition, this steel belongs to the cold-work category of steel because it is shaped after cooling, usually at the ambient temperature.
D2 tool steel also experiences low distortion and has better machining quality compared to other high chromium steel due to its carbide forming elements.
AISI D2 is made following the air quenching process, giving it the ability to achieve and retain its hardness at different temperatures.
D2 steel Composition
- Carbon C 1.50%: Increases the edge retention, hardness, and tensile strength. It also improves steel resistance to wear, abrasion, and corrosion.
- Chromium Cr 12.0%: the formation of Chromium carbide Increases the hardness, tensile strength, and corrosion resistance of the blade.
- Molybdenum Mo 0.80%: It improves machinability and gives D2 steel the characteristic air hardening property.
- Vanadium V 1.10%: Increase wear resistance and toughness, it also improves corrosion resistance. Vanadium acts by improving the grain structure and the carbide structure of the steel.
- Manganese Mn 0.45%: improves the strength and hardness of steel. When the steel is heat-treated, hardenability is improved with increased manganese.
- Silicon Si 0.40%: Increases strength and heat resistance.
- Phosphorus P 0.03%: Improves machinability and hardness.
- Sulfur S 0.03%: Improves machinability.
Properties of D2 steel
D2 steel hardness
According to the Rockwell C hardness scale, D2 has a Rockwell hardness of 60 HRC but may reach up to 64HRC depending on the tempering temperature. With such hardness, a blade made from this steel can hold edges for a long time in addition to admirable wear resistance.
D2 Wear resistance
D2 steel is known for its excellent wear resistance. If you ask around knife users, they will tell you that D2 takes the crown in wear resistance.
This feature is attributed to the good mix of chromium, carbon, vanadium, and manganese in its composition. This property makes the D2 knives the best for abrasive cutting compared to other types of steel on the market.
D2 steel Edge retention
As always, steel with high hardness makes blades with good edge retention, which is true with D2 tool steel. The edge retention of D2 is better than that of 154CM, grade 440C and it is similar to that of CPM 3V steel but significantly worse than that of S35VN, S30V, and M390 steels.
The high carbon levels in its composition make this possible. If you are on the market for a knife that will not require frequent sharpening, look into the options made from AISI D2 steel.
D2 Steel Toughness
You rarely get hardness and toughness from the same steel, and this is the case with D2. Since D2 has high hardness, its toughness is low. The low toughness is attributed to the large carbides that negatively affect its toughness.
While there are other knife steels with better toughness than D2, it offers enough hardness to handle light chopping without breaking. The toughness of D2 knife steel is similar to that of Z-Max steel, 154CM, BD1N, and Bohler N690 steel.
However, consider tougher steels like X50CrMoV15 or CPM M4 steel if you are looking for a knife to handle tough applications like batoning and chopping. Low alloy tool steels like 1084 steel will be better for knives that require higher toughness.
D2 Steel Sharpening
Sharpening D2 steel is a challenging task considering that it is hard steel and high on abrasion and wear resistance. It will take you more effort and time to achieve an ultra-sharp edge with D2, but this is compensated with long edge retention, reducing the frequency of sharpening.
Inexperienced knife sharpeners struggle to get an edge from D2 knives, but it is doable, especially using diamond or ceramic sharpeners on the blade. Whetstones also work well going through the different grits.
D2 Steel Corrosion resistance
The fact that D2 is not stainless steel discourages many people from buying it because of the assumption that it rusts. To clear the air, let us answer a very common question, does D2 steel blade rust? The honest answer will be yes; it does rust but not as easy as many knife users assume.
While it does not contain the required chromium levels to make it stainless steel, its 12% chromium content is enough to resist corrosion with good care and maintenance. You cannot keep your D2 knives dirty and wet and expect them not to rust, it requires regular clean-up after use.
D2 Steel comparison
D2 vs S30V
The major difference between D2 steel and S30V steel is that D2 steel is conventionally produced steel while S30V is powder metallurgy steel. S30V steel is better knife steel than D2 steel as it exhibits a more balanced approach in performance aspects like toughness, corrosion resistance, and edge retention.
A key difference to also note between D2 and CPM S30V steel is that D2 is nonstainless tool steel while S30V steel is stainless steel with excellent corrosion resistance properties.
The fine microstructure and hard vanadium carbides of S30V steel enable it to perform slightly better than D2 in edge retention. The fine microstructure also contributes to the better toughness of the S30V steel blade over the D2 blade steel.
D2 tool steel outperforms S30V steel in wear resistance due to the high amount of carbon in its composition that enables it to attain a higher Rockwell hardness than S30V stainless steel.
CPM D2 vs D2
CPM-D2 is a powder metallurgical variant of the D2 steel. It is a relatively new steel blade in the market following advancement in steel production by Crucible CPM technology.
CPM D2 steel is more refined and has reduced chromium carbide required in die steels, thus it provides better toughness value than regular D2 steel and responds better to heat treatment.
D2 Steel Equivalent
D2 steel equivalent includes Bohler K110 steel, Cr12Mo1V steel, JIS SKD11 Steel, and 1.2379 steel. Another steel that offers close to similar performance to AISI D2 is M2 steel.
Also read CPM CruWear steel review, an upgraded version of D2 steel.
Is D2 knife steel good?
The high wear resistance and edge retention make D2 steel a perfect choice for knives. You might struggle a bit with sharpening, but D2 knives are quality and affordable options.
It is suitable blade steel for a seasoned knife maker and user alike. Reputable Knifemakers like Bob Dozier have solely built their name in knife blades by utilizing D2 blade steel.
See Also: Niolox Steel Review, An improved D2 steel with added Niobium
If you were struggling to decide on whether or not to buy a D2 steel knife, this review should give you the go-ahead. A blade from D2 is a good option compared to other non-stainless steels on the market.
D2 steel is conventionally produced and thus widely available from most tool steel companies, this makes it cheaper and easier to find as compared to powder steel. You can also find D2 as Bohler K110 Steel.