Are you an engineer or machinist trying to decide between stainless steel 17-4PH and 420? It may seem like a daunting task, but the truth is that these two materials are very similar in many ways.

The differences between them can be broken down into composition, properties, applications, heat treatment, machining, and cost. In this article we will explore each of those categories to help you make an informed decision when selecting one over the other.

We all want to feel like part of something bigger than ourselves - like a community of engineers and machinists who understand the complexities of steel selection.

So let's get started on our journey together as we break down the differences between 17-4PH and 420 stainless steel!

Overview of 17-4PH and 420 Stainless Steel

Overview of 17-4PH and 420 Stainless Steel

Comparing these two alloys, 17-4PH and 420, can be overwhelming – but we'll break it down to help you make the best decision.

Both of these stainless steels are known for their strength and corrosion resistance, making them popular choices in a number of industries.

17-4PH is an age-hardened alloy that has high tensile strength and good wear resistance, while 420 offers excellent corrosion resistance with medium hardness.

When deciding between the two, it helps to consider how they will be used.

17-4PH is ideal for applications where its higher strength is needed, such as aircraft components or medical equipment.

Its machinability makes it well suited for parts requiring complex shapes and tight tolerances.

On the other hand, 420 stainless steel is often used in cutlery due to its superior corrosion resistance and edge retention capabilities.

It's also great for applications where wear and tear are more likely such as bearings or gears.

Ultimately, both alloys offer great benefits depending on your needs – so choose wisely!


You can imagine the difference between 17-4ph and 420 as a contrast between waves of rust and silver in a sea of strength - both are powerful, but which is right for you? Both stainless steel grades are composed of iron, chromium, carbon, and other elements such as nickel and manganese.

The primary difference lies in their respective amounts: 17-4ph generally contains 15%-17% chromium, 3%-5% nickel, 3%-5% copper with the remainder being iron. 420 stainless steel typically contains 12%-14% chromium with the rest being iron.

These small differences in composition result in large impacts on performance. For example, 17-4PH has superior strength and hardness to 420 grade stainless steel due to its higher levels of alloying elements like nickel and copper. With this understanding, it's easy to see why 17-4PH is an excellent choice for applications requiring good corrosion resistance and high strength or hardness while also needing low costs.

On the other hand, 420 may be preferred for needs that require better machinability or if cost is not a major concern. Knowing what your application needs helps you decide which grade will best suit your preferences!


When it comes to stainless steel 17-4ph and 420, both have their own unique properties.

Corrosion resistance, strength, and hardness, as well as temperature resistance, are important aspects to consider when making a choice between the two.

Both offer excellent corrosion resistance. However, 17-4ph offers greater strength and hardness at elevated temperatures than its counterpart.

Additionally, 420 is more resistant to temperatures up to 500 degrees Celsius compared to 17-4ph's range of 200 degrees Celsius.

Corrosion Resistance

Wondering which material offers the best corrosion resistance? Let's take a look at 17-4ph and 420 to find out.

Stainless steel 17-4ph is known for its high corrosion resistance, making it ideal for many applications in marine, aerospace, and nuclear industries. It's also incredibly resistant to oxidation due to its high chromium content, meaning it won't corrode easily under normal conditions.

On the other hand, 420 stainless steel has a lower resistance to corrosion compared to 17-4ph. It may be suitable for some low stress environments where exposure to salt water or chemicals is minimal. However, it's not recommended for highly corrosive environments as its lower chromium content makes it more susceptible to rusting over time.

Ultimately, when choosing between stainless steel 17-4ph and 420 for your project, consider the environment you'll be using them in - if you're looking for something that can withstand harsh conditions without corroding quickly, then opt for 17-4ph instead of 420.

Strength and Hardness

Fear no heavy-duty job - 17-4ph and 420 stainless steels offer unbeatable strength and hardness!

With an impressive combination of durability and corrosion resistance, these two popular grades of stainless steel are a great choice for any industrial application.

17-4PH is a precipitation hardened martensitic stainless steel renowned for its high tensile strength, wear resistance, and excellent corrosion resistance. This grade is often used in aerospace applications due to its exceptional fatigue strength.

On the other hand, 420 Stainless Steel offers a slightly lower tensile strength than 17-4ph but still provides great toughness and hardness. Both grades can be heat treated to increase their hardness even further.

So when the job calls for something strong, trust that both 17-4PH and 420 will get it done with ease!

Temperature Resistance

Not only are 17-4PH and 420 stainless steels strong and hard, they're also temperature resistant - perfect for any application that needs to withstand the heat!

Each of these materials offers excellent thermal stability up to temperatures of 572°F (300°C). This means that they're suitable for a variety of industries including aerospace, automotive, chemical processing, medical equipment manufacturing, and food & beverage production.

Plus, with their high level of resistance to corrosion, you can trust that your operation will be efficient and reliable in even the most extreme conditions.

So no matter what type of environment you need a stainless steel solution for, 17-4PH and 420 stainless steels have got you covered.


Determining which alloy is best for your project can be a difficult decision - but understanding their applications might help you make the right choice.

Stainless steel 17-4PH and 420 are commonly used in many different industries, with each having its own advantages:

  • 17-4PH: Automotive parts, aerospace components, and food processing equipment.
  • 420: Medical implants and instruments, cutlery and kitchenware, and surgical instruments.

No matter what application you're considering, both of these stainless steels offer superior corrosion resistance as well as excellent strength. This makes them ideal for projects that require long term durability and reliable performance under extreme temperatures.

So while there may be some differences between the two alloys, both will serve your needs effectively depending on the nature of your project.

Heat Treatment of 17-4PH and 420 Stainless Steel

Heat Treatment of 17-4PH and 420 Stainless Steel

Gaining a better understanding of the heat treatment process for 17-4PH and 420 stainless steels can help you decide which one is right for your project. So let's take a look at what to expect.

17-4PH stainless steel is usually heat treated by being hardened in either an air or oil furnace. This type of steel has excellent strength and corrosion resistance after being hardened.

The 420 stainless steel can also be hardened by heating it to about 980 degrees Celsius (1800°F) before quenching it in oil or water. Once the material has been quenched, the hardness will reach up to 50 HRC on Rockwell C scale.

Knowing how these two types of stainless steel respond to heat treatment can give you insight into which one might be a better fit for your project needs.


Machining of Stainless Steel

Now that you have a basic understanding of the heat treatment process for 17-4PH and 420 stainless steel, let's take a look at how these materials perform when machining. Machining is an important component of the fabrication process and can be the difference between success or failure in many applications.

When it comes to machining, both 17-4PH and 420 stainless steel perform well but with some differences:

  • 17-4PH has better corrosion resistance than 420 stainless steel, which makes it easier to machine without having to use coolants or lubricants.
  • 420 stainless steel has higher hardness ratings than 17-4PH making it more difficult to machine but also giving it greater wear resistance.

Both materials are generally easy to work with since they respond well to traditional machining processes such as drilling and tapping.

Cost Comparison

Comparing the costs of 17-4PH and 420 stainless steel can help you decide which material is best suited for your project.

Both materials have their advantages and disadvantages when it comes to cost, so it's important to weigh the pros and cons before making a decision.

17-4PH stainless steel is typically more expensive due to its higher corrosion resistance, making it ideal for applications that require a longer lifetime.

However, 420 stainless steel may be a better option in terms of initial cost as it requires less maintenance compared to 17-4PH.

In addition, 420 stainless steel tends to be more readily available than its counterpart, meaning that ordering and shipping times could be shorter.

Ultimately, when deciding between these two materials, you need to consider the long-term costs associated with each one in order to determine which will provide you with the most value over time.

Advantages and Disadvantages

Now that we've taken a look at the cost comparison of stainless steel 17-4ph versus 420, let's take a closer look at their advantages and disadvantages. You may be wondering which one is right for you - and it all depends on your needs.

Here are some pros and cons to consider when deciding between these two types of stainless steels:

  • 17-4PH:
    • Advantages: It's tough, corrosion-resistant, durable, holds an edge well, and can be hardened by heat treatment. It's also relatively easy to machine compared to other grades of stainless steel.
    • Disadvantages: It tends to be more expensive than other types of stainless steel due to its high nickel content. Additionally, welding can be difficult because it doesn't respond well to conventional hot-working techniques.
  • 420:
    • Advantages: It's highly corrosion-resistant due to its high chromium content, making it ideal for food processing applications as well as outdoor use in saltwater environments. Additionally, it's inexpensive compared with other grades of stainless steel.
    • Disadvantages: Its low hardness means that edges don't stay sharp for very long, and the material can easily become scratched or marred if handled incorrectly during machining or fabrication processes.


When it comes to stainless steel, there are a few options to consider and each has its own set of advantages and disadvantages. Let's take a look at what you need to know in order to make the best decision for your project.

17-4PH is known for having good strength and corrosion resistance, while 420 stainless steel offers better hardness and wear resistance than 17-4PH. Both materials are cost-effective, but taking into account the specific needs of your project will help you decide which one is right for you.

At the end of the day, it all comes down to finding the right balance between cost and performance when selecting a material for your project. If you're looking for corrosion resistance and good strength, then 17-4PH is probably your best bet. However, if hardness and wear resistance are more important factors, then 420 stainless steel may be the way to go. Ultimately, both materials have their own unique benefits that can be taken into consideration as part of an informed decision-making process.