Stainless Steel Types For CNC Machining: Why Doesn’t Stainless Steel Rust

stainless steel types

There are many types of stainless steel, but why doesn’t stainless steel rust? What are the specific types of stainless steel and their benefits? As a leading corporation in this field, this blog post will answer all your questions about stainless steel! Stay tuned.

What Is Stainless Steel?

Stainless steel is an alloy of iron, chromium, and nickel. It is a material that is highly resistant to corrosion and is often suitable for a wide variety of industrial and consumer applications. Therefore, it is ideal for machining stainless steel parts.

Properties of Stainless Steel

1. Excellent corrosion resistance: The biggest feature of stainless steel is its excellent corrosion resistance, which makes it much longer lifespan than other types of materials.

2. High-temperature resistance: Stainless steel can withstand high temperatures up to 1200℃ without deformation or damage.

3. Pressure resistance: Stainless steel has good pressure resistance and can be suitable for various occasions that require high pressure.

4. Easy to clean: Stainless steel is easy to clean and does not require special cleaning methods or chemicals.

5. Aesthetic appearance: Stainless steel has a bright, shiny surface that makes it look very attractive.

6. Non-toxic: Stainless steel is made of non-toxic materials and is safe to use.

7. Durable: Stainless steel pipe is very durable and can last for many years.

8. Recyclable: Stainless steel is recyclable and can be used again after being recycled.

Common Stainless Steel Types

There are five common stainless steel types in CNC machining.

Austenitic stainless steel

The most popular type is austenitic stainless steel, which is used in everything from kitchen appliances to surgical instruments.

This versatile material is corrosion-resistant and has a high degree of resistance to heat, making it ideal for many different environments.

Ferritic Stainless Steel 

Ferritic Stainless Steel is a type of stainless steel that contains chromium and carbon. This steel has high strength and resistance to corrosion.

Ferritic steels are typically suitable for strength and corrosion resistance applications, such as in the automotive and construction industries.

Martensitic Stainless Steel 

Martensitic stainless steel is a specific type of stainless steel alloy that can be hardened and tempered through a heat treatment process. The alloy contains a high carbon content, which allows it to be hardened and tempered to a wide range of strength and hardness levels.

And they are suitable for knives, surgical instruments, and cutting tools.

stainless steel

Austenitic-ferritic (duplex)

Duplex stainless steel contains both austenitic and ferritic microstructures. It gives the steel greater strength and corrosion resistance than other types of stainless steel. The most common grades of duplex stainless steel are 2205 and 2507.

It is highly resistant to stress corrosion, cracking, and pitting. It also has a higher yield strength than austenitic stainless steel. The higher strength of duplex stainless steel allows for thinner gauges and designs, saving material costs.

Plus, it has excellent weldability thanks to its ferritic component. It can be welded with all standard welding processes, including gas tungsten arc welding, plasma arc welding, and shielded metal arc welding.

Precipitation Hardening

Precipitation hardening (PH) stainless steel contains aluminum, copper, 15-17.5% chromium, and 3-5% nickel. This steel is a type of stainless steel that has exceptional wear, corrosion, and welder fatigue resistance.

PH stainless steels are heat treatable and can be hardened or strengthened through heating and cooling processes. They can be heat treated to a wide range of hardness levels, depending on the grade, making them ideal for use in many different applications.

Related Material Articles:

Aluminum Alloys For Aluminum CNC Machining: How To Select Right Alloy

How To Choose The Right CNC Machining Materials?

Why Do Metals Rust?

Rust is the common name for a type of corrosion that occurs when iron or steel is exposed to oxygen and water. Rusting is an electrochemical process that occurs when metal is exposed to air and moisture, causing it to break down and form a new compound. The new compound, called rust, is less stable than the original metal and can cause serious damage to the metal over time.

There are a few different theories about why metals rust, but the most likely explanation is that it’s simply an oxidation reaction. When iron or steel is exposed to air and moisture, the oxygen in the air reacts with the metal to form oxide compounds. These oxide compounds are then attacked by the water, causing the metal to corrode.

metal rust

What Makes Stainless Steel Stainless?

Most people know that stainless steel is a durable, low-maintenance material that doesn’t rust or stain. But what many don’t realize is just how stainless steel is made stainless by the addition of chromium. 

Stainless steel contains a much higher chromium content than carbon steel. Stainless steel contains at least 10.5% chromium and no more than 1.2% carbon and other alloy elements. Chromium is a shiny, hard metal that’s used in a variety of applications, including jewelry and car trim.

When it’s added to steel, it forms a thin chromium oxide layer on the surface of the metal that acts as a barrier to oxygen and other corrosive elements. This film is what gives stainless steel its distinctive luster and resistance to rust and staining.

In a nutshell, the reasons are as follows:

1. Stainless steel is an alloy of iron, chromium, and other metals that is highly resistant to rusting and corrosion.

2. The chromium in stainless steel forms a thin layer of oxide on the surface of the metal that prevents further oxidation and protects the underlying metal from corrosion.

Applications Of Stainless Steel

Stainless steel is a widely-used material in architecture because of its durability and aesthetic appeal. Stainless steel is suitable for both structural and ornamental purposes.

Some of the most common applications of stainless steel in architecture are:

1. Exterior cladding

Stainless steel is often used as an exterior cladding material. It is available in a variety of finishes, including brushed, mirror-like and matte. Stainless steel cladding can give a building a modern and sleek appearance.

2. Facades

Stainless steel is a popular material for facades. It is durable and has a low maintenance cost. Stainless steel facades can give a building a unique look.

3. Curtain walls

Curtain walls are another common application of stainless steel in architecture. They are usually made of glass, but they can also be made of stainless steel. Stainless steel curtain walls are durable and have a high resistance to corrosion.

4. Roofing

Stainless steel is also suitable for roofing. It is available in a variety of colors and finishes. Stainless steel roofs are durable and have a low maintenance cost.

5. Interior design

Stainless steel is also often suitable for interior design. It is available in a variety of finishes, including brushed, mirror-like, and matte. Stainless steel can give a room a sleek and modern appearance.

6. Furniture

Stainless steel furniture is becoming increasingly popular. It is strong and durable.

7. Hardware

Stainless steel is also suitable for a variety of hardware applications. It is available in a variety of finishes, including brushed, mirror-like, and matte. Stainless steel hardware is often suitable for public spaces and office settings.


In conclusion, stainless steel is a metal alloy that does not corrode or rust in the presence of water and oxygen. It has many applications in industries such as food service, construction, automotive, and more. There are various types of stainless steel available on the market, each with unique properties to meet different needs. If you need to machining stainless steel parts, please contact us now!


Does stainless steel 304 rust?

No, stainless steel 304 does not rust. It does not rust under normal atmospheric conditions. However, it occurs in more corrosive environments or when the composition of the steel contains impurities. It is because it is an alloy that contains chromium and nickel. The chromium forms a protective oxide film on the surface of the metal, which prevents oxygen from getting to the steel and causing it to rust. The nickel also provides corrosion resistance.

Does SS 316 rust?

The answer is yes, but it takes significantly longer for SS 316 to start showing signs of corrosion than other types of steel.