Description Thick Len Wid Price Qty Stock

M4 Carbon Steel, CPM M4, Flat Ground

 .105 in 23.5 in 2.0 in $111.40
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 BSM4-0105-235020G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .105 in 26.2 in 2.0 in $124.20
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 BSM4-0105-262020G 3

M4 Carbon Steel, CPM M4, Flat Ground

 .105 in 12.5 in 2.3 in $68.10
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 BSM4-0105-125023G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .105 in 23.5 in 2.3 in $128.10
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 BSM4-0105-235023G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .105 in 26.2 in 2.9 in $180.10
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 BSM4-0105-262029G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .125 in 23.5 in 1.5 in $89.10
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 BSM4-0125-235015G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .124 in 11.6 in 2.0 in $58.30
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 BSM4-0124-116020G 5

M4 Carbon Steel, CPM M4, Flat Ground

 .125 in 23.5 in 2.0 in $118.70
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 BSM4-0125-235020G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .125 in 23.5 in 2.5 in $148.40
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 BSM4-0125-235025G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .148 in 27.3 in 1.5 in $117.60
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 BSM4-0148-273015G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .148 in 27.3 in 2.0 in $156.80
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 BSM4-0148-273020G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .150 in 27.3 in 2.0 in $158.40
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 BSM4-0150-273020G 4

M4 Carbon Steel, CPM M4, Flat Ground

 .143 in 27.3 in 2.4 in $183.20
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 BSM4-0143-273024G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .169 in 12.5 in 1.5 in $57.50
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 BSM4-0169-125015G 3

M4 Carbon Steel, CPM M4, Flat Ground

 .163 in 23.5 in 1.5 in $105.10
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 BSM4-0163-235015G 2

M4 Carbon Steel, CPM M4, Flat Ground

 .169 in 23.5 in 1.6 in $115.40
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 BSM4-0169-235016G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .168 in 12.5 in 2.0 in $76.40
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 BSM4-0168-125020G 3

M4 Carbon Steel, CPM M4, Flat Ground

 .159 in 12.7 in 2.0 in $74.30
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 BSM4-0159-127020G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .159 in 23.5 in 2.0 in $137.40
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 BSM4-0159-235020G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .169 in 23.5 in 2.0 in $144.20
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 BSM4-0169-235020G 2

M4 Carbon Steel, CPM M4, Flat Ground

 .159 in 12.7 in 2.6 in $96.60
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 BSM4-0159-127026G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .159 in 23.5 in 2.6 in $178.70
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 BSM4-0159-235026G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .208 in 23.5 in 2.0 in $170.00
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 BSM4-0208-235020G 1

M4 Carbon Steel, CPM M4, Flat Ground

 .206 in 23.5 in 6.0 in $505.90
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 BSM4-0206-235060G 1


 

Steel Glossary:
B/U CPM CG
CRA CRHT ESR
FG FGHT HRA
HRDA HRPA
See All Blade Materials By Thickness:

InformationM4 Carbon Steel Information and Composition

Condition:
Our M4 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:
27 = Maximum Toughness
56 = 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. 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:

Description:
This steel gets very sharp. Its edge holding is excellent. If you use M4 to make a knife do most of your finishing before heat treating because it is very hard to finish after. I think M4 has gotten much more popular since it has been used in cutting competitions.

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 Sheets:
Bohler M4 (S690) Data Sheet
Crucible M4 Data Sheet
Zapp M4 Data Sheet

Heat TreatM4 Heat Treat Information:

Preheat: Heat to 1,500-1,550°F, equalize. Second pre-heat stage at 1,850-1,900°F suggested for vacuum or atmosphere hardening.

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.

1,875-2,200°F. Hold time at temperature:

  • 1,875°F - 45 minutes
  • 1,975°F - 30 minutes
  • 2,050°F - 20 minutes
  • 2,100°F - 15 minutes
  • 2,150°F - 10 minutes
  • 2,200°F - 5 minutes

For cutting tools use 2,150-2,200°F. For cold work applications use 1,875-2,125°F. Quench in air or positive pressure quench to below 125°F, or salt or interrupted oil quench to about 1,000°F, then air cool to below 125°F. A fast quench rate from hardening temperature to below 1,100°F is critical to achieve optimum heat treat response. A slower cooling rate below 1,000°F may be used to minimize distortion.

Temper: Double temper at 1,000°F minimum. Triple temper recommended when hardening from 2,100°F or higher. 2 hours minimum each temper. Air cool to room temperature between tempers.

Cryogenic Treating: After the first temper may improve long term dimensional stability by transforming retained austenite. Any cryogenic treatment must be followed by a temper.

Use the graph below to select your temperatures:

CertsM4 Certs

Chemical Composition Certification*

  1. Click on the button below to get the chemical composition of the steel you purchased.
  2. You will be required to enter the three character code written in red letters on your steel.
  3. If you do not see red letters on the steel, your specific chemical composition is not in the system.

Lookup Cert
 
* This material is NOT certified for medical or aerospace applications.
  .

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.

BSM4 BSM4-0040 BSM4-0060 BSM4-0080 BSM4-0100 BSM4-0120 BSM4-0140 BSM4-0160 BSM4-0180 BSM4-0200 BSM4-0220 BSM4-0240 BSM4-0260
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