M390 Stainless Steel
Cert
Heat Treat
InfoAll the M390 we sell is blanchard ground. Learn Why…
| Alloy – Condition | Thick | Len | Wid | Price | Qty | Stock |
|---|
M390 Stainless Steel, Flat Ground |
.078 in | 22.7 in | 1.5 in | $112.90 |
-
+
|
BSM390-0078-227015G | 1 | |||
M390 Stainless Steel, Flat Ground |
.078 in | 23.5 in | 1.5 in | $116.90 |
-
+
|
BSM390-0078-235015G | 1 | |||
M390 Stainless Steel, Flat Ground |
.078 in | 22.7 in | 1.9 in | $143.00 |
-
+
|
BSM390-0078-227019G | 1 | |||
M390 Stainless Steel, Flat Ground |
.079 in | 22.7 in | 1.9 in | $144.30 |
-
+
|
BSM390-0079-227019G | 1 | |||
M390 Stainless Steel, Flat Ground |
.078 in | 11.6 in | 2.4 in | $92.30 |
-
+
|
BSM390-0078-116024G | 1 |
M390 Stainless Steel Information and Composition
Condition:
Our M390 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:
8 = Maximum Toughness
61 = 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:
M390 has very good edge holding and poor toughness. M390 Made using Bohler's third generation powder metallurgy process. It can be finished to a mirror polish with some effort. This alloy has become the high end factory knife steel.
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. All the M390 we sell is blanchard ground. Learn Why...
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 M390 Data Sheet
M390 Heat Treat Information:
Preheat: Heat to 1,400-1,450°F. Equalize temperature.
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 to 2,050-2,150°F. Soak for 30 minutes. Lower austenitizing temperatures maximize impact toughness. Higher austenitizing temperatures maximize edge holding.
Quench: Plate or air quench to 125°F.
Temper: Temper immediately after cryo or quench if cryo is not performed. Temper for 2 hours.
Cryogenic Treating: Cryo is recommended for austenitizing temperatures at or above 2,100°F. Cool to -100 °F, remove from cryo and allow blade to warm to room temperature in cool air.
Use the graph below to select your temperatures:
M390 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.
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.
Bohler/Uddeholm HIP Can History
A hot isostatic press (HIP) can is the can that powdered metal is put into when making a billet using the powder metallurgy process. When Bohler/Uddeholm (BU) makes stainless steel, they use a can made from 304 stainless steel. The can filled with metal powder is placed into the HIP. The HIP is pressurized and the powder and can are pressed into a solid billet.
The billet is forged/rolled into sheet. As the billet is rolled thinner, the HIP can on the outside of the billet also gets thinner. The ends of the can remain thick.
In 2010, BU contacted AKS and asked us to help them introduce their alloys to the North American knife market. At the time we were not aware of the HIP can on BU stainless steel. We helped introduce the BU alloys. The PM stainless alloys were popular with knifemakers who liked the cleanliness and performance of the alloys.
We soon received reports from knifemakers that the steel would not get hard and some knives looked like they had a san-mai shell on the outside of the steel. We investigated the problems and learned about the HIP can. We asked BU to remove the HIP can. They refused and we stopped selling their PM stainless steel alloys.
In 2017 we were approached by BU again and asked to sell their PM stainless steel alloys. We asked if the HIP can issued was resolved. We were told the HIP can was removed. We resumed buying their PM stainless steel alloys. When we received sheets of BU steel, we cut coupons, ground a bevel and etched the coupon. We also heat treated the coupons. We did not find the HIP can when etched and the rockwell hardness was correct. We stopped testing in mid 2018.
In 2019 we were contacted by a knifemaker who found a san-mai looking shell on a batch of knives he was making from M390. We also had a similar report with Vanax. We immediately tested both alloys and found HIP can. We removed all the M390 and Vanax from the website and contacted BU. After months of investigation we’ve come to the following conclusions. BU did institute a process change and removed the thick ends of the HIP can. They do not remove the thin can on the surface of the sheet. BU states the HIP can on the surface is no more than .007 of an inch thick.
As of May 2019, we’ve decided to continue selling BU PM stainless steel alloys. All the alloys will be blanchard ground to remove the HIP can.
All Bohler Uddeholm powder metallurgy stainless steel alloys have the HIP can. Beware of Elmax, M390, M398 & Vanax that have the factory pickled descaled finish. These sheets still have the HIP can.
Submit your review | |