Types Of Stainless Steel – Grade 304 Vs. Other Grades Comparison

Stainless steel is a term used to describe a specific type of steel alloy with minimum amounts of 10.5% chromium. This is alloyed with varying amounts of nickel and other metal elements added to produce a more corrosion-resistant material.

The standard for this type of steel, ASTM A-240 / A-240M, covers the construction, design, and performance requirements that can be used in a variety of applications.

One of the most dominant types is 304 stainless steel. What sets it apart? This article will focus on the basics of stainless steel, comparing its cost, composition, and applications. We also look at machining 304 stainless steel and how it’s a favorite for many.

What is 304 Stainless Steel? Machining 304 Stainless Steel

304 stainless steel (also called 18/8 stainless steel) is an austenitic steel alloy with a minimum chromium content of 18%. Chromium is responsible for giving steel its hardness and corrosion resistance.

This type of steel can be used in a variety of applications such as gas turbines, aerospace, and power generation. The addition of other metal elements such as nickel and molybdenum further enhances its properties, making it useful specifically for the food and medical industries.

The metal density is 7.93 g/cm3 (0.304 lb. / in3).

Most companies offering CNC machining services, including CNClathing.com, use this type of stainless steel metal to fabricate high-quality products. Here are the properties that set it apart:

Type 304 Stainless Steel Properties

The following are some of the properties that affect its performance:

• Excellent corrosion resistance and heat resistance (of up to 800 ℃) 
• Resistant to scaling and pitting
• High tensile strength; useful for making thin sheets
• Good ductility, even at low temperatures (-40°F)
• High weldability and machinability
• Excellent modulus of elasticity (193-200 GPa or 28000 – 29000 ksi)
• Thermal conductivity of 16.2 W/m-K, or 112 BTU-in/hr-ft²-°F

The combination of chromium and molybdenum imparts excellent resistance to acids and alkalis. It is also highly resistant to atmospheric corrosion.

How is 304 Stainless Steel Made?

The composition of 304 stainless steel makes it easier to produce, meaning there are no major difficulties when manufacturing the metal. It can be rolled into sheets, plates, rods, and tubing.

The processes used in making this alloy include hot rolling, cold rolling (cold drawing), extrusion, plasma cutting, and wire electric drawing. Properties common to all of these processes include:

• Good annealing resistance
• Improved formability due to cold rolling (deformation)
• High work-hardening rates, with increased hardness in thicker sections

Comparison of Stainless Steel Metal – Grade 304 vs. Other Grades

Each metal grade has its features and uses. We compare Grade 304 with Grades 430, 409, 316, 310, 303, and 201, among others.

Additionally, we will help you choose the best CNC Machining stainless steel, ideal for your specific needs.

316 vs.304 – What is the Difference Between 304 and 316 Stainless Steel?

Composition: Grade 316 stainless steel is a molybdenum-containing austenitic chromium-nickel steel alloy. It has a minimum of 16% chromium and 10% nickel content. On the other hand, Grade 304 chromium composition is 17.5%-19.5%, while nickel is 8%-10.5%.

Properties: Grade 316 stainless steel is harder, stronger, more weldable, and has a lower carbon content. It is highly resistant to pitting corrosion in the presence of chlorides. Grade 304 stainless steel cannot be hardened by heat treatment.

Applications: The two alloys are suitable for use in equipment that must resist corrosive attack. However, Grade 316 stainless steel is better due to its higher resistance to pitting corrosion in the presence of chlorides at high temperatures. As such, you can use it when the final product will be exposed to the marine environment.

Cost: Grade 316 is more expensive than Grade 304

304 vs. 303 Stainless Steel 

Composition: Grade 304 stainless steel contains at least 18% chromium and 8% nickel, while Grade 303 requires chromium between 17%-20% chromium 8% nickel. However, Grade 303 contains less carbon (0.08%) than the 0.10-1.2% in Grade 304

Properties: The two alloys are similar in terms of corrosion resistance, weldability, and formability. However, Grade 303 stainless steel is more machinable than Grade 304 since it contains a little sulfur. On the contrary, Grade 304 is more weldable than Grade 303.

Applications: Grade 303 stainless steel is used where formability is critical. You can also use it to make thin sheets and tubing. However, you cannot use it when making a product that will be exposed to corrosion or high-temperature conditions.

Grade 304 stainless steel is more resistant against corrosion induced by seawater, making it ideal for use in marine applications.

Cost: Grade 303 is more expensive than 304.

304 vs. 18/8 Stainless Steel 

Composition: 18/8 stainless steel comprises 18% chromium and 8% nickel. 304 stainless steel contains at least 18% chromium and 8% nickel, while 303 contains 17%-20% chromium and 8-10% nickel.

As such, the 18/8 is a designation representing the composition of chromium and nickel in the metal. It is a series of metal, with most 300 series (301,302, 303, and 304) having that composition.

These metals are used in equipment that must resist corrosive attack. For example, those used in water systems, marine applications, and chemical processing.

Stainless Steel 201 vs. Stainless Steel 304

The difference between the two metals lies in the composition of chromium and manganese. Grade 304 stainless steel contains more chromium, which improves its corrosion resistance.

On the other hand, stainless steel 201 boasts a higher level of manganese. As such, it is suitable for industries that require high output of items not exposed to corrosive elements. Here’s an overview of the properties:

• 304 stainless steel has a better corrosion resistance than 201
• Grade 304 is tougher than 201
• Grade 304 is more rust-resistance than 201
• Grade 304 is more expensive and looks darker than 201

310 vs. 304 Stainless Steel

Grade 310 stainless steel contains more chromium (24-26%) than Grade 304 (10-20%). Additionally, type 310 contains 19-22% nickel while type 304 only contains 8-10.5% nickel.

As such, Grade 310 metal is harder than 304. If you’re looking for ductile material, you should for the 304 option. Grade 310 is only ideal when you need hardenabilities, such as when making kilns, coal gasifier internal components, steam boilers, burners, refractory anchor bolts, and radiant tubes.

304H vs. 304L Stainless Steel 

The primary difference between 304H and 304L is the percentage of carbon. A higher level of carbon decreases the metal’s corrosion resistance. In this case, L stands for Low Carbon while H stands for High Carbon content.

Here are some of the properties of the two metals:

• 304L has low carbon content (less than 0.03%), while 304 H contains more than 0.04% carbon. As such, 304L is more corrosion resistant than 304H.
• 304H offers high-temperature strength when exposed to more than 800 degrees Fahrenheit. 
• 304L has a better yield strength (a 0.2% yield strength of 35ksi (241 MPa) vs. 0.2% yield strength of 42ksi (289 MPa) of 304H.

430 vs. 304 Stainless Steel Difference

Grade 430 stainless steel does not contain nickel, while Grade 304 contains 10.5% nickel. Additionally, the 430 version is magnetic, while 304 is not. Other differences include:

• 430 has less corrosion resistance than 304 stainless steel.
• 430 is more ductile than 304 stainless steel. You can press the metal into different shapes, including tubes for structural use. It is also more machinable.
• 304 stainless steel is formable and more weldable than the 430 version
• Unlike 430 stainless steel, Grade 304 hardens during cold working
• Grade 304 stainless steel is more expensive than Grade 430

304 vs. 409 Stainless Steel 

Composition: Grade 409 stainless steel metal comes with 10.5% to 11.75% chromium and approximately 0.5% nickel. On the other hand, 304 stainless steel has more chromium (18-20%) and nickel content (8%-10%). Additionally, 409 stainless steel is about 90% iron, while the 304 version has lesser iron composition.

Here’s how the two grades compare:

• Grade 304 is tougher than 409 since it has greater tensile strength at 235ksi (1524 MPa) vs. 208ksi (1370 MPa).
• Grade 304 is more corrosion resistant than 409.
• Grade 304 is not magnetic, while the 409 version does exhibit magnetism.
• Grade 409 does not polish as well as Grade 304
• Grade 409 is cheaper than Grade 304

Which Stainless Steel Metal Grade Is Best?

Having looked at various grades of stainless steel, you can conclude that some are more suited for specific applications. As such, make sure you pick your metal according to your project requirements.

If you’re looking for a budget-friendly material, go with grade 430 stainless steel. It is less corrosion-resistant but relatively cheap. Grade 304 stainless steel is ideal when you want the most anti-corrosion resistance. At the same time, it’s formable, welded, machinable, and has a perfect polish. Grade 304H stainless steel is suited for high-temperature applications.

Grade 310 stainless steel offers better hardness than 304 but less corrosion resistance than 304L or 316 metal. It is ideal for use in equipment that does not require high ductility.