CPM M4 Steel Complete Guide

CPM M4 Steel has amazing properties, thus making it one of the commonly used steels in the tool industry.

Due to its strength and versatility, it can be used when making knives, punches, and other cutting tools.

If you ever thought of using CPM M4 steel in your machinery projects but weren’t quite sure whether it’s what you needed, this article may just enlighten you on the basics.

CPM M4 steel can prove useful in different scenarios because it is highly resistant to abrasions and is equally tough.

It is able to achieve most of its functions due to its chemical composition and unique structure.

Chemical Composition of CPM M4 Steel

To give you an in-depth understanding of the chemical structure and how M4 steel performs in terms of toughness, wear resistance, machinability, and corrosion resistance, you can refer to the table below.

Compound  SymbolPercentage %

To break this down further, let us look at each compound and the role that it plays in the structure of CPM M4 steel;


As an alloy component, tungsten plays a special role in ensuring CPM M4 steel maintains its hardness even when put to heavy-duty use.

It also increases resistance against wear and tear, and that is why most tools that are made from M4 steel tend to last.


Having the second-largest percentage, molybdenum increases strength and overall machinability, thus giving you an easy time when forging M4 steel.


Chromium is one of the most powerful alloying elements, so its inclusion in the composition of CPM M4 steel greatly increases hardenability.


Just like chromium, vanadium improves hardness, thereby making CPM M4 steel more resistant to wear.


Carbon provides CPM M4 steel with multiple benefits since it boosts hardenability, corrosion resistance, just to mention but a few.


This is yet another compound that improves the strength of CPM M4 steel.


Manganese increases both strength and hardenability


Sulfur makes CPM M4 steel more machinable.

As you can see each of the compounds has a special role that it plays in ensuring CPM M4 steel stays intact in all work scenarios.

Is M4 steel good for Knifemaking?

CPM M4 steel has exceptional edge retention and is equally durable, so it can make knives that are of superior quality.

As a matter of fact, it can be used when forging just about any type of cutting tool since it has desirable properties.

However, since M4 steel is very hard, you may have a difficult time sharpening your knives since the steel does not grind easily after it is heat-treated.

On the bright side, M4 knives won’t wear out, and neither will they corrode easily due to the steel’s strong structure.

Can CPM M4 steel catch rust?

Yes, M4 steel can be affected by rust mainly because it contains low amounts of chromium.

As such, tools that are forged from this steel alloy should be stored properly to prevent them from rusting.

More to this, always ensure that the tools are coated in oil or any other rust inhibitor that is readily available.

With adequate care, tools that are forged from CPM M4 steel can last for a very long period of time since their chances of breaking are low.

The other advantage that you will get from using CPM M4 steel is that it does not chip easily, so your knives will remain functional throughout the period that you will have them.

This means that edges won’t deteriorate prematurely, and neither will the blade break when it is in use.

What does CPM stand for in CPM-M4 steel?

Crucible Particle Metallurgy, commonly referred to as CPM, is an advanced technique that is used in the production of high-grade steel alloys that are not only tough but also versatile.

This process enhances durability by boosting toughness, corrosion resistance, and also increases machinability.

And since CPM-M4 t is produced through this procedure, it can be used in forging tools that will provide you with consistent performance.

Particle metallurgy steel alloys perform better compared to most steel alloys that are produced conventionally.

Nevertheless, this does not mean that CPM steels such as M4 are the best because some conventional steel alloys are superior to them.

When working with steel, you should always remember that there is no perfect alloy since all the materials have their cons and pros, which may favor your work or go against it.

How is CPM-M4 steel made?

The production of CPM-M4 steel is rather complex, so we are only going to cover the key steps to give you a rough idea of how this alloy is made.

Just like the conventional steelmaking process, the different types of metals that are to be used have to be heated to melting point.

As a result, they will form a thick homogenous molten metal, which is then passed through an atomization machine that will slowly cool it to form fine particles.

After this, the particles are subjected to high-temperature conditions to create the desired microstructure.

The steel alloy that is formed after this can be processed several times to the satisfaction of the manufacturer.

The good thing with this process is that the particles cool abruptly, thus preventing segregation.

In addition to this, the metals that are used form strong carbides that make the steel even tougher.

As stated, this is just a summary of the steelmaking process, so you can carry out further research to learn more.

Final Thoughts

CPM-M4 steel can provide you with a long list of benefits as long as you use it the right way. It can particularly come in handy when forging handheld cutting tools like knives.

And the fact that it is resistant to corrosion makes it a suitable steel for crafting different types of tools, including those that are likely to be used in unforgiving conditions.

We have tried our best to cover all the basic facts about CPM-M4 steel, so we hope that this article has been helpful.

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