The D2 steel was heat treated and ground by Devin Thomas. The PSF27 specimens were heat treated by Michael Drinkwine. The CPM-D2 specimens were heat treated and ground by myself. All were heat treated with a 30 minute hold time, plate quench, and cryo followed by a double temper.
Full Answer
How does cryogenic processing affect D2 wear resistance?
There are many studies on the effects of cryogenic processing on D2 in terms of wear resistance. Some of those claim that a long hold time, such as 36 hours, at cryogenic temperatures lead to an improvement in edge retention.
How did you heat treat your D2 steel?
The D2 steel was heat treated and ground by Devin Thomas. The PSF27 specimens were heat treated by Michael Drinkwine. The CPM-D2 specimens were heat treated and ground by myself. All were heat treated with a 30 minute hold time, plate quench, and cryo followed by a double temper.
How does DCT affect martensite formation at cryogenic temperatures in D2 steel?
In relation to the effect of DCT, the present data adds information on the kinetics of martensite formation at cryogenic temperatures in D2 steel and suggests that DCT not only reduces the fraction of retained austenite in the material, but also the total number of retained austenite regions.
What happens to the toughness of steel after cryogenic or subzero processing?
The most commonly reported result of subzero or cryogenic processing of steel was a reduction in toughness [3,5-7,9-10,13,15,17,18,20,22]. Typically the reduction in toughness after cryo or subzero processing is attributed to the transformation of retained austenite. Retained austenite is a ductile phase and therefore can help improve toughness.
How do you treat Cryo steel?
To perform cryogenic hardening, metal is first exposed to heat using a conventional heat treatment process. Next, the metal is slowly cooled using liquid nitrogen. Once the metal is submerged or otherwise exposed to liquid nitrogen, its temperature begins to drop.
How cryogenic treatment is done?
Cryogenic processing is performed by slowly cooling parts in a controlled bath of liquid nitrogen or a freezer, holding the parts until equilibrium is reached with the liquid's temperature. Nitrogen is a liquid at -320℉. Cryogenically processed parts are generally held for one hour per inch of thickness.
Do you need to heat treat D2 steel?
D2 should always be annealed after forging. Heat slowly to 1550°-1600°F, hold until entire mass is heated through, and cool slowly in the furnace (40°F per hour) to about 1000°F, after which cooling rate may be increased. Suitable precautions must be taken to prevent excessive carburization or decarburization.
Can you harden D2 steel?
Hardening: D2 tool steel is extremely sensitive to overheating during hardening – do not overheat. Pre heat slowly to 750/780°C and soak. Continue heating to the final hardening temperature of 1000/1030°C and allow the component to equalise.
How do you cold harden steel?
Cold rolling is the most common method of work hardening. This involves the metal being passed through pairs of rollers to reduce its thickness or to make the thickness uniform. As it moves through the rollers and is compressed, the metal grains are deformed.
How long does it take for cryogenic hardening to occur?
Typical cryogenic treatment consists of a slow cool-down of -5 °F per minute (-3°C per minute) from ambient to -320 °F (-196°C), a soak for 24 to 72 hours, and warm up to ambient temperature.
How do you harden D2 tool steel?
A recommended heat treatment would be 1850-1900°F for 30 minutes, plate quench, cryo, and temper 300-500°F. Without cryo the austenitizing temperature should be no higher than 1875°F.
Can you heat treat D2 with a torch?
4:3212:11how to heat treat D2 Steel - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd all of that is reasonably straightforward you heat it up you dunk it in oil and you're done butMoreAnd all of that is reasonably straightforward you heat it up you dunk it in oil and you're done but when it comes to hardening. There's a lot more to it and I'll run through some of it just.
How much does D2 grow in heat treat?
Estimating Size Change During Heat Treat An Uddeholm data sheet shows that when D-2 tool steel, 3.15" x 3.15" x 3.15", is austenitized at 1,870 degrees F for 30 minutes and quenched in a vacuum furnace with 2 bar nitrogen overpressure, it grows in one dimension while shrinking in the other two.
What Rockwell is D2?
55-62 HRCThe D2, is a tool Steel that offer a good toughness and great hardness with a right edge retention, it has a Rockwell hardness range of 55-62 HRC.
What is the hardness of D2 steel?
between 54 – 61 HRCD2 can reach an approximate tempered hardness range between 54 – 61 HRC and features an approximate compressive yield strength of around 275 ksi to around 319 ksi as hardness increases.
Can D2 steel be welded?
Because of its crack sensitive nature elevated caution must be used when welding on D2 steels. If applying D2 filler material (938) on a D2 base material, the unit must first be fully annealed prior to welding and then rehardened after welding.
What is cryogenic treatment for tubes?
Cryogenic treatment is a process of cooling steel alloy down to very low temperatures (−190 °C) to increase its surface hardness to improve its resistance to wear, the practical application being to extend the life of cutting tools, gear teeth, moving engine parts, that kind of thing.
What is Cryo coating?
Cryo Coating is a mod that increases. Cold damage and status chance on Arch-melee weapons by 15% per rank for a maximum of 60% at rank 3.
How does a cryogenic oxygen plant work?
Liquid from the tank is compressed to high pressure in a cryogenic liquid pump. It is then vaporised in an ambient air evaporator to produce gaseous oxygen. The high-pressure gas then can pass into cylinders via the gas manifold or fed into a customers product pipeline.
What is cryogenic machining?
Cryogenic machining deals with the direct application of cryogen in the cutting zone to reject heat to reduce tool wear rate and improve surface integrity. Cryo-processing of the tool is a method to improve tool resistance to wear by treating them cryogenically before the machining process.
Abstract
Cryogenic treatment has been recognized by a few methods for expanding apparatus life of numerous cutting instrument materials, hence enhancing efficiency essentially. However genuine components which ensure better instrument execution are as yet questionable.
References (1)
ResearchGate has not been able to resolve any citations for this publication.
How long does it take for a knife to reach cold temperatures?
Time in liquid nitrogen or dry ice needs to be no longer than for the knife to reach the cold temperatures. In other words 30-60 minutes is sufficient. There are many studies on the effects of cryogenic processing on D2 in terms of wear resistance.
When was D2 used?
D2 has been used in knives since at least the 1960s, in part because of its ubiquity as a tool and die steel. It continues to see use both by custom knifemakers as well as production knives. In particular it has seen popularity in recent years in “budget” production folders. In 2002 a “sprayform” version of D2 was introduced by Danspray, ...
When was D2 patented?
D2, PSF27, and CPM-D2. I previously wrote an article about the history of D2 here. It was patented in 1927, a modification of earlier “high carbon, high chromium” steels that had been used since at least 1910 as an alternative to high speed steels which had a large amount of expensive tungsten. D2 has been used in knives since at least ...
Is heat treatment better for powder metallurgy steel?
In some cases the hardness after heat treatment can be somewhat better for powder metallurgy steels because of the finer and more evenly distributed carbides. However, in my heat treatment tests I did not see a big difference in hardness between conventional D2 and CPM-D2.
Is PSF27 better than CPM-154?
The toughness and edge retention of PSF27 is no better than CPM-154, but CPM-154 has the benefit of being truly stainless. Therefore the only reason to use PSF27, as I see it, is because it is somewhat cheaper than CPM-154.
D2 Steel – Tool, Die and Blade Steel
D2 steel is a kind of ledeburite tool steel, which is the most available and popular among D-series tool steels. Its hardness can reach 60+HRC after heat treatment.
D2 Tool Steel Properties
The following tables show D2 tool steel properties including chemical composition, physical and hardness, etc.
Applications
D2 metal can be used to manufacture cold work die steels with large cross-sections, complex shapes, high impact resistance, and high wear resistance. Typical applications including:
D2 Steel Equivalent Material
AISI D2 steel equivalent to European EN (Germany DIN, British BSI, French NF…), ISO, Japanese JIS and Chinese GB standard (For reference).
What happens to austenite when it is bent?
Transformation of Austenite During Use. Steels with austenite will transform to martensite when a stress is applied, such as when the steel is bent, pulled, or otherwise deformed. This is known as a strain-induced or stress-induced transformation. This increases the strength of the steel as strong martensite is formed.
What is subzero processing?
Subzero or cryo processing prior to tempering also shifts the tempering-hardness curve to lower temperatures when using the secondary hardening range of tempering [2]: This means that in general, a lower tempering temperature is required to achieve the same hardness level with secondary hardening.
What is the interrelation between subzero and cryo?
One important interrelation to keep in mind with subzero and cryo studies is the transformation of retained austenite in tempering. With sufficiently high tempering temperatures all/most of the retained austenite is transformed without any cold treatment.
What are the properties of steel that are affected by cryo processing?
The other two primary properties of steel affected by cryo processing are toughness and wear resistance. Both of these properties can be difficult to pin down as they have high variability. Tool steels are known for their relatively poor toughness which means we are often comparing small numbers.
What temperature does austenite harden?
Therefore tempering in the secondary hardening region above 400°C can lead to both high hardness and also the elimination of retained austenite.
Does austenite reduce steel hardness?
Retained austenite reduces the yield strength of steel independent of hardness because it is a low strength phase. Stress-induced transformation of retained austenite to untempered martensite can lead to reduced toughness, though it improves fatigue behavior.
Does cryogenic processing reduce steel toughness?
In general, cryogenic processing reduces the toughness of steel due to the loss of retained austenite which is high in toughness. This is not always the case, however, as was found in the Z-Wear toughness study. There is also little or no difference in toughness when adding a cryo step to steels given the high temperature secondary hardening temper. Retained austenite reduces the yield strength of steel independent of hardness because it is a low strength phase. Stress-induced transformation of retained austenite to untempered martensite can lead to reduced toughness, though it improves fatigue behavior. On balance I think cryogenic processing leads to a better combination of strength and toughness properties, though there may be scenarios where retained austenite is beneficial.
How long to heat treat D2?
The paper strongly suggests that there would be a benefit in refining the carbide structure of the steel. How about this heat treat for D2: Preheat 1200F 30 minutes. Preheat 1450F 30 minutes. Austenize 1875F 30 minutes. Air/plate quench to room temperature. Cryo in liquid helium 1 day.
Why is liquid nitrogen used?
liquid nitrogen is used primarally because it is easier to store (in a proper tank several months) and since it ids a liquid I can imagine that procces working better
What is duplex steel?
This is usually a very soft and corrosive resistant structure often used in cheaper kitchen cutlery. Duplex: A form of hybrid between austenitic and ferritic steels (it’s sometimes called austenitic-ferritic) that tends to be more corrosion resistant than the austenitic structure and harder than the ferritic structure.
What are the four structures of stainless steel?
The Four Stainless Steel Structures: Martensitic: A hard structure built up around the composition of iron, chromium, and carbon. This structure can be heat treated. Austenitic: A face-centric cubic structure that can not be hardened by heat treatment. Generally results from the addition of nickel, manganese, and nitrogen.
Does SOG use cryo?
SOG clearly does it on at least some of their knives since they explain the process in their buyer’s guide. Rumor has it Benchmade uses some kind of cryo process, and Spartan Blades touts their “ double deep cryo heat treatment” in most of the product descriptions of their Gold Grade knives.
Is soft steel hard?
This is steel we’re talking about. Even soft steel is pretty damn hard, and most of us will never use our knives in a way that would make us notice the added toughness between regular steel and cryogenically treated steel.
Can steel be made tougher?
In theory, yes. But like everything with a complex craft, it depends on the materials and the application. If done right, the process should make the steel tougher, but not all steel types react to the process in the same way.
Does cryogenic treatment help with knives?
Yes, cryogenic treatment improves some types (high alloy) knife steels. It does more for long term toughness than any kind of hardness or sharpness. Probably every large knife manufacturer is doing it on some knives. No, we probably aren’t paying extra for knives as a result.
