What Is P20 Steel?

Perhaps you’re reading this P20 steel guide because you’re doing research on various kinds of steel, so that you can find just the right type of steel for the knife you’re looking for. It’s unlikely, though, that you’ve found this guide because you’ve stumbled upon a P20 steel knife, because there’s no such thing readily available in the knife market.

In other words, P20 steel is not a good steel for knives. It wasn’t designed for that purpose at all!

In this guide, you’ll discover why it’s not really for knives, and what it’s actually meant for instead.

What is P20 steel?

P20 steel is a type of tool steel that’s generally associated with injection mold steels. It’s actually quite versatile, as it works for molds and other similar industrial components. For molds, it’s easy to work with.

However, if you’re researching steels for knives then you better look elsewhere. P20 steel is definitely not a steel for knives. You won’t find any commercially available knife that’s made with P20 steel. Even custom knife makers won’t work with it, because it’s not easy to work with and the results aren’t good for knives at all.

If you’re a mold maker, then you should already be familiar with P20 steel. In fact, it’s so familiar to mold makers that this familiarity is one of its advantages. You know what you’re getting when you’re making molds with P20 steel.

Common Uses of P20 steel

• Plastic Molds
• Die Holders
• Backers
• Frames for Plastic Pressure Dies
• Hydro-Forming Mold Tools
• Bolsters
• Die Holders
• Rails
• Shafts
• Wear Strips

P20 steel Chemical Composition

Let’s check out what elements make up the P20 steel recipe, with the percentages for each element:

• Carbon, 0.28 to 0.4%
• Manganese, 0.6% to 1%
• Silicon, 0.2% to 0.8%
• Chromium, 1.4% to 2%
• Molybdenum, 0.3% to 0.55%
• Copper, 0.25%
• Phosphorus, 0.03%
• Sulfur, 0.03%

Carbon, 0.28 to 0.4%: Many experts regard carbon as the most crucial element for a knife steel, and here there’s simply not enough of it to matter. The low carbon content simply doesn’t lead to good cutting performance, not even for large axes.

Manganese, 0.6% to 1%: The manganese tends to cause effects similar to that of carbon. It helps with tensile strength and hardenability, and even assists with taking out impurities like oxygen and sulfur from the molten steel.

Silicon, 0.2% to 0.8%: This also helps with removing oxygen bubbles from the molten steel. It strengthens the iron in the alloy, and also boosts the hardness.

Chromium, 1.4% to 2%: This doesn’t qualify the P20 as stainless steel, since you need 10% to 12% chromium for that. This leads to rather poor corrosion resistance, which is why P20 steel generally needs some kind of corrosion-resistance plating as well. The chromium can also help in increasing both the hardness and the toughness of the steel.

Molybdenum, 0.3% to 0.55%: Even in amounts of less than 1%, the molybdenum boosts the corrosion resistance and also the hardenability of the P20 steel. It increases the creep strength and strength in high temperatures.

Copper, 0.25%: This compensates for the low chromium content, as it helps with corrosion resistance. In a small way, it also helps with hardenability.

Phosphorus, 0.03%: Yes, it’s a very tiny amount of phosphorus, and that’s because it’s generally considered an impurity in the steel. Too much phosphorus leads to brittle steel. But with only this small amount of phosphorus, its addition helps with the steel strength and corrosion resistance.

Sulfur, 0.03%: Again, it’s a miniscule amount due to how sulfur is also considered an impurity. But a tiny bit helps to improve the machinability of the P20 steel.

P20 steel hardness

It’s true that with the proper preparation, you can get a decent HRC level with P20 steel. You can go as far as the high 50s, or even get to 60 HRC. But it takes too much work to reach those levels.

Does P20 steel rust?

Yes, it does, and quite easily too. It doesn’t have much chromium or other corrosion-resistant elements. It’s not stainless steel at all, and even stainless steel can rust.

The good news is that if you’re working with the P20 steel, you have lots of plating options to improve the corrosion resistance. But that plating has to be added to the process.

Properties of P20 steel

Basically, the properties of P20 steel make it a good choice for molds. Mold-makers cite the following features to explain why they like to use P20 steel:

Familiarity with P20

Many experts have worked with heat-treating P20 steels before, so they’re familiar with the steel and know what to expect with various heat treatments. There are rarely any unpleasant surprises that may waste their time and effort.

Easy Machinability for Molds

It’s not easy to machine if you’re trying to make a knife, and it’s almost twice as hard as carbon steel to work with if that’s the case.

But for molds, the P20 can be machined in its pre-hardened and tempered state. It can then be treated again after machining, if that’s necessary.

Easily Accessible

The P20 is readily available, so you won’t have to look to hard to find it when you need it. And when you do need it, the price is quite reasonable.

Low Carbon

This is one of the main reasons why it’s not really good for knives. You can’t get any decent cutting performance out of the steel, compared with even other budget steels for knifemaking.

Low Corrosion Resistance

This is another main issue with P20 steel. It doesn’t qualify as stainless steel at all. While it’s true that there are some venerable steels that also have low corrosion resistance (and therefore need constant oiling), with P20 steel you get both low corrosion resistance and low carbon content. That’s not a good combination for knives.

P20 Equivalent Steels or Alternative

If you’re researching mold steels or perhaps trying to make molds yourself, then the P20 steel is a good option. But there are other choices available, with better performance though at higher costs.

P20 steel vs 718 Steel

The 718 steel is also a popular option for pre-hardened old steels. The P20 is generally more affordable, but then in the crucial factors, 718 is simply better. It’s offers superior levels for hardenability, polishing performance, hardness, and machinability.

P20 steel vs 4140

It’s true that the average alloy compositions for both steels are almost the same. They even cost almost the same as well. But 4140 steel offers greater strength for its weight, especially tensile strength.

P20 steel vs H13

Yes, the H13 steel costs more than the P20 steel. But then again, the H13 steel offers better performance for molds. It’s easy to machine, offer good hardness levels, and exhibits high impact strength. However, its corrosion resistance isn’t all that impressive, either.

Is P20 steel good for Knives?

The short answer is no, it’s not good for knives. The main issue here is that you have so many other different steel alloy options out there, and all of them are better for knives than P20 steel. Compared to all of these steels, the P20 simply can’t come close.

It’s like asking a 12-year-old schoolyard basketball player to compete in the NBA. You can even use Google to try and find knives made with P20 steel, and you won’t find anything.

(Yes, we found a P20 pruning knife for sale. But the P20 refers to its knife model designation, and not to the material for the blade.)

Pros & Cons of P20 steel

Conclusion

The P20 steel isn’t really found in knife blades at all, and you’re more likely to encounter it in molds. Even for budding knifemakers, there are plenty of better steel options to use than P20 steel (and that includes practicing your knifemaking techniques).

Look for other steels if you need a knife that actually works. There’s really no such thing as a commercial P20 steel knife—Google it if you want to check. There are other steels out there that offer better knife blade performance, and at even lower prices. With P20, it’s really all about making molds.