K390 Carbon Steel
Cert
Heat Treat
Info| Description | Thick | Len | Wid | Price | Qty | Stock |
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K390 Carbon Steel, HRDA |
.095 in | 11.6 in | 1.4 in | $44.60 |
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BSK39-0095-116014 | 1 | |||
K390 Carbon Steel, HRDA |
.095 in | 11.6 in | 1.5 in | $47.80 |
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BSK39-0095-116015 | 1 | |||
K390 Carbon Steel, HRDA |
.095 in | 23.5 in | 1.5 in | $96.80 |
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BSK39-0095-235015 | 11 | |||
K390 Carbon Steel, HRDA |
.095 in | 11.6 in | 2.0 in | $63.70 |
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BSK39-0095-116020 | 6 | |||
K390 Carbon Steel, HRDA |
.095 in | 23.5 in | 2.0 in | $129.10 |
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BSK39-0095-235020 | 4 | |||
K390 Carbon Steel, HRDA |
.095 in | 23.5 in | 2.4 in | $155.00 |
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BSK39-0095-235024 | 2 |
K390 Carbon Steel, Flat Ground |
.143 in | 13.0 in | 1.5 in | $101.50 |
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BSK39-0143-130015G | 4 | |||
K390 Carbon Steel, Flat Ground |
.143 in | 23.5 in | 1.5 in | $183.40 |
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BSK39-0143-235015G | 3 | |||
K390 Carbon Steel, Flat Ground |
.143 in | 23.5 in | 2.0 in | $244.50 |
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BSK39-0143-235020G | 4 | |||
K390 Carbon Steel, Flat Ground |
.143 in | 23.5 in | 6.0 in | $733.60 |
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BSK39-0143-235060G | 1 |
K390 Carbon Steel Information and Composition
Condition:
Our K390 has been properly annealed and is in the soft condition. You do not have to do any non-standard wasteful processes before heat treating. The steel must be heat treated to get to a hardened state. Follow the heat treat recipe and the steel will harden.
Ratings:
NT = Maximum Toughness
71 = Maximum Edge Holding
The rating scale is 0-100, 0 being minimum and 100 being maximum. The ratings are the maximum potential of the alloy. If the value shown is "NT", the testing has not been performed. I do not recommend heat treating to the maximum value. Choose a heat treat recipe that results in the attributes you want.
Thank you to Dr Larrin Thomas for all the testing he performed and information he has provided. Buy his book Knife Engineering to learn more about knifemaking.
Alloy Comparison Table:
     
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Description:
Bohler K390 has close to the same edge holding as A11 but is tougher. This steel is difficult to grind, finish and sharpen. Once it is sharp it will stay sharp for a long long time. I wish this steel was more available.
Flat Ground:
Any alloy that has “Flat Ground” in the description has been Blanchard ground. Our tolerances for flat grinding are +-.001” across 12”. You can identify Blanchard grinding by circular grind marks. Do not be mislead by other descriptions. Others try to pass off less accurate types of grinding with lower tolerances as flat grinding. This is why we call out our tolerances.
Information Sources:
There are many sources of information regarding knifemaking. Some sources, like Dr. Larrin Thomas of Knife Steel Nerds, are excellent. Other sources are not as credible. It is important to vet the your information sources. Be careful of anyone who says the way to heat treat 1095 or O1 is to heat to non-magnetic and quench in used motor oil. Anyone who publishes this type of information is not credible. When possible, we use information from manufacturers and industry experts.
AI Information:
The latest trend of bad information is from Artificial Intelligence (AI). Multiple companies have AI programs. AI collects and compiles information. The problem is, AI is does not know if the information is accurate or garbage. When asked, AI regurgitates and merges good and bad data. Beware of AI data when researching materials. If you read material information that sounds like it was written by a poetry graduate student, compares materials that are not similar, contains blatantly false information, etc, it was probably AI generated. At AKS, we never use AI to generate material information.
Data Sheet:
Bohler K390 Data Sheet
K390 Heat Treat Information:
Preheat: 1,500-1,550°F, equalize.
Austenitize: It is critical to not exceed the maximum austenitize temperature. If you overshoot the maximum temperature by a small amount, toughness will go down dramatically.
Heat rapidly from preheat. For optimum wear resistance, soak for 5 to 15 minutes 2,150°F. For balance of wear resistance and toughness, soak for 15 to 30 minute 2,050°F. For maximum toughness and minimum distortion in cooling, soak for 30 to 60 minutes 1,975°F.
Quench: Plate, air or medium oil quench to 125°F.
Temper: Temper immediately after quenching. Typical temperature range is 1,000-1100°F. Do not temper below 1,000°F. Hold at temperature for two hours then air cool to ambient temperature. Double tempering is required. Triple tempering is required when austenitized at 2,100°F or higher.
Use the graph below to select your temperatures:
K390 Certs
Chemical Composition Certification*
- Click on the button below to get the chemical composition of the steel you purchased.
- You will be required to enter the three character code written in red letters on your steel.
- If you do not see red letters on the steel, your specific chemical composition is not in the system.
* This material is NOT certified for medical or aerospace applications.
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B/U: Bohler / Uddeholm
Bohler and Uddeholm are two large steel companies based in Europe. Both companies make high quality steel alloys and are subsidiaries of Voestalpine.
Cross Grain:
Steel is toughest when it is cut with the grain. However, we occasionally get pieces that were cut across the grain. We call this “cross grain”. The cross grain billets are discounted.
CRA: Cold Rolled Annealed
Cold rolled steel has a nice finish. The surface is bright and smooth. It can be darker on the edges of the sheet showing some heat coloring from annealing. Cold rolled alloys have minimal runout. The steel is annealed (soft).
CRHT: Cold Rolled Heat Treated
Cold rolled heat treated applies to only some 15N20. The steel is heat treated to approximately HRC 45. This alloy is used extensively for sawmill bandsaw blades. The sawmills require the steel be heat treated.
Even though this 15N20 is heat treated, it is not full hard. It is easy to work with metal working tools. When drilling this 15N20, It is important to keep constant pressure and use a lubricant.
ESR: Electroslag Remelt
Electroslag remelting is a process of remelting and refining a steel alloy to make it cleaner. The result is very clean steel. The steel is annealed (soft).
FG: Flat Ground
The AKS definition of flat ground is +- .001 inch runout across 12 inches. The surface of the steel is ground until it is bare steel with a uniform grind pattern. The front and back of the billet are parallel.
FGHT: Flat Ground Heat Treated
Flat ground heat treated applies to only some 15N20. The steel is heat treated to approximately HRC 45. This alloy is used extensively for sawmill bandsaw blades. The sawmills require the steel be heat treated.
Even though this 15N20 is heat treated, it is not full hard. It is easy to work with metal working tools. When drilling this 15N20, It is important to keep constant pressure and use a lubricant.
The AKS definition of flat ground is +- .001 inch runout across 12 inches. The surface of the steel is ground until it is bare steel with a uniform grind pattern. The front and back of the billet are parallel.
HRA: Hot Rolled Annealed
Hot rolled steel has mill scale and is dirty on the surface of the steel. The mill scale is easily removed by multiple processes such as pickling or sand blasting. The steel is annealed (soft).
HRDA: Hot Rolled Descaled Annealed
The steel is heated and run between rollers to achieve the desired thickness. As the steel cools, scale forms on the surface of the sheet. The scale is removed by sand blasting or shot blasting. After blasting, the surface of the sheet has a rough finish. The steel is annealed (soft).
HRPA: Hot Rolled Pickled Annealed
The steel is heated and run between rollers to achieve the desired thickness. As the steel cools, scale forms on the surface of the sheet. The scale is removed by immersing the sheet in a bath of acid. The process is called pickling. The acid removes the scale. After pickling, the surface of the sheet has a rough finish. The steel is annealed (soft).
PESR: Pressurized Electroslag Remelt
PG: Precision Ground
The AKS definition of precision ground is less than .001 inch runout across 12 inches.
PM: Particle Metallurgy
Alloys using particle metallurgy processes are made from powdered metal. The powder is put in a can and pressed into a solid billet in a hot isostatic press.
CPM: Crucible Particle Metallurgy
Crucible is a steel company based in USA. They produce multiple steel alloys. Some of the alloys are made using the Crucible Particle Metallurgy i.e. CPM process.
The first step in the CPM process is heating the steel until it is a liquid. The liquid is sprayed through a small nozzle and forms into a powder. The steel powder is packed into a steel container that is welded shut. The container containing the powder is placed into a hot isostatic press or HIP. The HIP heats the container and compresses the steel powder into a solid billet. After the billet cools the container is removed. The remaining billet has a consistent composition.
The major advantage of the CPM process is producing alloys that would not be possible using traditional steel production processes.
CG: Cross Grain
Steel is toughest when it is cut with the grain. However, we occasionally get pieces that were cut across the grain. We call this “cross grain”. The cross grain billets are discounted.
Submit your review | |
According to Larrin Thomas's rating of K390 at 5.5, Elmax at 4, and 4V at 7, puts K390 directly in the center of these other two. So by comparison, 4V = 41 and Elmax = 24, would put K390 at 32.5 on the toughness scale. The sums of the other two can be combined and divided in half to scale K390 or they can be subtracted 8.5 from the 4v, and 8.5 added to the Elmax to reach the K390's toughness rating of 32.5.
My favorite steel alloy. It holds an edge for a long time but is tougher than Rex121 and 10V.