A2 is in the hall of fame for high-carbon steels. This might be because A2 is arguably one of the first tool steels to come into existence. A2 dates back to the 1960s and has been used over the years for multiple applications. Even with the rise in multiple budget imported steels, A2 proudly stands its ground as an air tool steel with exceptional hardness and toughness alike.
A2 steel is also a great option because it is an air-hardening tool steel. This steel has plenty of history, and we’ll get into more details about A2 steel in this article: A2 steel’s composition, properties, heat treatment and how it compares to other competitive steels in the market.
A2 Steel Review | What is A2 Steel?
A2 steel is an air-hardening tool steel that dates back to the 1960s or earlier. A2 is also called AISI A2 and is produced by Crucible Industries. A2 has created a name for itself for being one of the toughest steels at high hardness. You usually give up either toughness or hardness in a knife steel, but with A2 you don’t have to compromise on either.
A2 has a bigger reputation of being used for combat knives and hunting knives, though there’s no good reason why it wouldn’t make a great kitchen knife. A2 has been used over the years for specific custom outdoor knife requirements by many custom knife makers, including but not limited to Phill Hartsfield and Rob Criswell. The renowned Australian knife maker Aaron Gough makes outdoor survival knives in A2 steel alone, so you know it’s gotta be great.
A2 has great wear resistance, which is why it works so well as an outdoor knife. There’s no conceivable way to tell how old an A2 knife is, it pretty much looks the same since the day you bought it. Other knives that have a similar carbon and chromium content tend to be low of toughness but A2 has great abrasion resistance as well.
A2 isn’t just for knives, it can also be used for a variety of applications: particularly for tools that require high hardness, such as blanking and forming punches, hammers, woodwork cutting tools.
What is the Heat Treatment of A2 Steel?
A2 is a great knife steel for custom knife-making, but not everyone can deal with A2 heat processes in the comfort of their home forge set-up. That’s because it requires a lot of careful heating and cooling in the annealing and stress relieving processes to keep the balance of high hardness and toughness. Too much of hardening or tempering can result in offsetting the balance and too much of either hardness or toughness which can be detrimental to knife making.
A2 is automatically a high hardness steel due to its exceptionally high carbon content. Most of the heat processes involved are to reduce the hardness and increase its toughness. You can play around with the temperatures of the A2 heat processes in order to get the sweet spot of hardness and toughness that you desire.
Annealing is a heat process that involves slowly raising the temperature of a steel above its critical point. This results in lower hardness (which is desired for the already high hardness A2 steel) and greater ductability and flexibility. Annealing also increases the internal strength of the steel, making it more resilient and long-lasting.
The annealing process should be carried out at the temperature point of 1650°F and care should be taken that the steel doesn’t decarburize. You can ensure this doesn’t happen by performing the annealing process in a controlled atmospheric set-up, or through the use of pipes and containers.
One of the most important heat processes for A2 steel is stress relieving. Putting the steel through this process gets rid of any unnecessary internal stressors and results in a much tougher steel with better even grain distribution. This is a relatively quick heating process and can be carried out in one hour at the temperature range of 1200°F to 1250°F and should ideally be carried out just before the machining process.
Hardening is necessary for A2 steel because it is naturally higher in toughness. Hardening should be carried out in such a way that the hardness is high as well without compromising on toughness of the steel. A2 needs to be preheated to 1450°F – 1500°F and then held for a minimum of two hours at 1750°F – 1800°F
A2 should be quenched in either still air or force air such as a dry air blast. This would need to occur for as long as it takes for A2 steel to reach 150° and then you can move straight to tempering A2 steel.
Tempering involves slowly heating up a steel over a period of time to increase the internal stressors, reduce hardness and make it stronger. The longer you temper a steel at a lower temperature, the stronger it becomes.
For the ideal hardness of 62HRC for A2 steel, it should be tempered for a minimum of two hours at 400°F to 500°F. Not tempering the steel at all and letting it reach room temperature after quenching will result in a higher HRC, around 65.
What is the Composition of A2 steel?
We’ve mentioned already that A2 steel is a high-carbon and medium-alloy steel, but that’s not enough to understand what all the elements are. Each element contributes unique properties to the A2 steel. If you’re a budding knife enthusiast, you should really pay attention to the composition and percentages of steels. Soon enough, you’ll know the properties of the steel just by glancing at the ingredients and percentages used.
|Elements||Percentage Composition (%)|
- Carbon 1.05% – This is a very high amount of carbon. That’s why A2 is considered high-carbon steel. Anything above 0.50% is usually considered a high amount of carbon, so you can understand why A2 has such a high amount of carbide at 1.05%. Carbon definitely contributes to the hardness of the knife blade but also plays a big role in edge retention.
- Chromium 5.50% – Chromium generally contributes towards corrosion resistance, but in such less quantities, it’s playing more of a role towards grain distribution and hardness of A2 steel. Chromium needs to be 12-15% in order to provide corrosion resistance for the steel.
- Molybdenum 1.40% – Molybdenum is extremely important for the hardness and internal strength of steel. 1.40% is a very high percentage of molybdenum and A2 steel definitely benefits from this addition.
- Vanadium 0.25% – Vanadium has a triple impact on the hardness, toughness, and wear resistance of the steel? How? Vanadium actually impacts the grain structure of the steel itself. The power of Vanadium is one of the reasons why it’s so common as an alloy.
- Nickel 0.30% – Did you know that nickel is mainly used for the production of stainless steel knives? That’s because Nickel has an incredible effect in increasing the ductibility of the steel A2. The ductibility makes it much easier to work with and shape to form great knives. This definitely helps when you try making your own knife from A2 steel at home.
- Manganese 1.0% – Manganese contributes towards the machinability of A2 and makes it more brittle.
- Silicon 0.50% – Silicon is deoxidizing during the heating process of making A2 steel.
- Copper 0.25% – 0.25% seems like a very tiny amount, and it is, but this is enough for copper to work its magic. Copper significantly works towards the internal strength and structural integrity of A2 steel.
- Phosphorus 0.030% – Phosphorus also has a significant impact on the machinability of A2, making it much easier to work with and shape into knives.
- Sulfur 0.030% – Sulfur also plays an important role in increasing the machinability of A2 steel.
As you can see, A2 is high-carbon steel, with higher amounts of other alloying elements.
How Hard is A2 steel?
A2 steel is very high in hardness, making it hard enough for nearly any kind of application. This high carbon steel receives a score of 62-65 HRC on the Rockwell Hardness Scale. That’s very hard as far as knives go.
Depending on the tempering that was done in the heat treatment process, A2 steel could also be reduced to about 58HRC. However, the perfect A2 steel has a score of 62 HRC making it great for kitchen knives and outdoor knives alike.
What are the A2 Steel Properties?
Now that we’ve looked at the composition of A2 steel, it’s time to look at what A2 can offer as a steel in terms of its capabilities.
A2 Steel Hardness
A2 steel has incredibly high hardness. With an HRC score of 62-65, A2 steel is as hard as they come. This makes it great for outdoor survival knives as well as hunting knives, since you’ll rarely find a substance harder than your knife in the wild!
However, if you’re planning to use A2 knives in the kitchen, be mindful that this high hardness can damage your cutting boards, particularly if they are wooden. You may want to use rubber cutting boards.
A2 Steel Toughness
The A2 steel has really impressive toughness. For the level of hardness that it can delivery, the toughness is definitely incredible. A2 has such great toughness that it can even pull off knife blades made thin since the toughness and great wear resistance will make it last for a really long time. The abrasion resistance also goes hand in hand with the toughness of the blade, making it much more resilient in the long run.
The A2 has more than enough toughness for an outdoor survival knife or hunting knife. That’s why it’s been used so often as a camping knife, the toughness lends itself to a really powerful blade that works well in outdoor settings. While A2 would be a great steel knife for kitchen knives as well, you may not need such high toughness unless you’re working on a butcher block and performing heavy carving or butchering.
A2 Edge Retention
A2 steel also has great edge retention. This can be credited to the high carbon content present in the A2 high-alloy steel. While sulfur plays a role in reducing the hardness of the A2 steel, it doesn’t reduce the edge retention capabilities. Good edge retention means that you won’t have to keep sharpening your knife and that it can stay sharp for a longer time. It retains the edge for a longer period of time.
A2 Ease of Sharpening
The A2 steel has high hardness and brittleness, making it difficult to sharpen. It’s not an easy task, but it’s not a tough chore either. You might have to take extra care and spend a few minutes with your sharpening tools to ensure that the sharp edge is really obtained over the entire edge of the knife. Most people consider A2 steel to be very easy for sharpening, but we are giving it a difficult score since we know that there are other beginner steels with more ease of sharpening.
A2 Corrosion Resistance
If you paid attention to the composition of A2 Steel section, you might have noticed that there’s less Chromium in A2. A steel needs to have a minimum of 12% Chromium content in order for it to be corrosion resistant. Since A2 has less than this, it doesn’t work as a stainless steel knife.
At the less Chromium content that it has, A2 is not a corrosion-resistant steel at all and it is quite prone to rust.
This means that any knives made out of A2 steel might be more prone to rust or corrosion over time. If you’re making a knife out of A2 steel on your own, then you might want to be extra careful while taking care of the knife. If you live in a humid area, then your knife is at the risk of catching rust very easily.
If you’re planning on buying a knife made from A2, you have the option of picking a manufacturer that coats the knife in an anti-corrosion finish. This will have a protective layer against corrosion and boost the lifespan of your knife.
Is A2 steel good for knives?
A2 steel is a great choice as a beginner steel for knives. If you’re just venturing into the world of knives and steels, A2 is not a tricky one to tango with. It provides a great balance of hardness and toughness, which means that it can be used in almost any application and has good durability.
We would advocate A2 being used as an outdoor knife more strongly, since that will enable you to make full use of A2 steel’s capabilities. A2 as a kitchen knife might be underutilized.
However, the biggest caveat of A2 steel is that it is not corrosion resistant. If you don’t want the extra chore of taking care of your knife diligently, we recommend that you opt for a A2 knife coated in anti-corrosion finish, made by certain manufacturers.
Is A2 a Stainless Steel?
No, A2 Steel is not a stainless steel because it does not contain any chromium content in it. It will catch rust easily if not taken care of properly. If you have purchased or made a stainless steel knife that doesn’t have a coating of anti-corrosion finish, then you take care of it by regularly oiling it. We recommend that you use food-grade mineral oil for the oiling, particularly if you own a A2 kitchen knife.
How does A2 Steel Compare to Other Knives in the Market?
Now that we’ve established that A2 is a great beginner knife, it’s time to look at some of the other beginner steel knives in the market, and how A2 compares to them.
A2 vs. 1095 Steel
|Ease of Sharpening||2/10||6/10|
1095 and A2 steels are both high-carbon steels, but A2 has the advantage in terms of Hardness and Edge Retention, as well as Toughness.
A2 vs. Maxamet Steel
|Ease of Sharpening||2/10||2/10|
Both A2 and Maxamet steel are high-carbon, high-alloys. Maxamet steel offers similar hardness and edge retention, but cannot compete with A2 in terms of toughness. Maxamet is much more premium steel, while A2 is more affordable.
A2 vs. 52100 Steel
|Ease of Sharpening||2/10||1/10|
A2 steel and 52100 steel are very common in the fact that they are both high-carbon high-alloying steels. A2 has higher toughness and edge retention than 52100, while 52100 is better in hardness.
Best A2 Steel in the Market:
A2 Tool Steel Rectangular Bar, Air Hardened/Annealed/Precision Ground, Precision Tolerance, ASTM A681, 1/8
If you’ve decided to take up the challenge of making your own knife from A2 steel, congratulations! As long as you own a home forge set up or furnace, you’re good to go and can get started right away.
This knife steel A2 bar is annealed and heat-treated for optimal hardness and toughness balance.
The measurements of this steel bar are 12″ x 1.5″ x 5/16″,. It is made in the USA and is especially easy to treat and form since it’s hot-rolled.
Here’s an incredible home Cast Master Forge Setup that you can get and start making your own customized knives!
A2 isn’t just a great beginner steel for someone looking to buy a knife, it’s also great for those looking to make their own knife! With great alloying metals, a good balance of hardness and toughness, and easy heat treatment: we’re glad A2 exists!
If you do choose to make your own knife from A2 steel, send us pictures and your experience with the steel. Good luck!