What is the Difference Between 430 vs 304 Stainless Steel?

Stainless steel comes in many different grades. Each grade brings its own unique chemical composition, tensile strength, and other characteristics. Let’s take a look at two of the most popular grades of stainless steel — 430 and 304.

What is stainless steel?

Like other forms of steel, stainless steel is an alloy of iron and carbon. What distinguishes stainless steel is the addition of chromium. To be considered stainless steel, the alloy must contain at least 10% chromium by weight. The chromium gives stainless steel its non-corrosive characteristics, which help lengthen the metal’s lifespan.

Carbon steel typically gets used for infrastructure, automobiles, and weapons. Stainless steel, by contrast, generally forms medical tools and food or beverage equipment. It tends to be brighter and more attractive than carbon steel.

What do the different grades of steel signify?

The steel industry classifies metals by grades in order to ensure the consistency and quality that precise steel processing requires. A steel’s grade is determined by all the factors that make that steel unique.

Steel standards organizations determine how to classify each grade of steel. Because there are several standards organizations around the world, the same grade of steel may be classified differently across national boundaries. Grades 304 and 430 are American Iron and Steel Institute (AISI) standards.

What is 430 stainless steel?

Type 430 stainless steel is a mild, corrosion-resistant metal that can be easily bent, stretched, or drawn.

It features the following chemical composition:

• Iron = Balance
• Carbon < 0.12%
• Chromium = 16-18%
• Nickel < 0.75%
• Manganese < 1.0%
• Silicon < 1.0%
• Phosphorus < 0.040%
• Sulfur < 0.30%

Its relatively high carbon content and lack of stabilizing elements make this grade difficult to weld.

Type 430 stainless steel has a minimum yield strength of 30 ksi and a minimum tensile strength of 65 ksi. Most commonly, type 430 stainless steel is used in cosmetic applications that require more aesthetic appeal than strength. It is available in 430 stainless steel sheet.

What is 304 stainless steel?

Type 304 stainless steel is the most widely used of all stainless steel grades. It generally appears in kitchen equipment and industrial applications.

This grade of stainless steel features the following chemical composition:

• Iron = Balance
• Carbon = 0.0 – 0.07%
• Chromium = 17.50 – 19.50%
• Manganese = 0.0 – 2.0%
• Silicon = 0.0 – 1.0%
• Phosphorous = 0.0 – 0.05%
• Sulphur = 0.0 – 0.03%
• Nickel = 8.0 – 10.5%
• Nitrogen = 0.0 – 0.11%

Type 304 can be welded to plain carbon steel using TIG or MIG welding.  This grade of stainless steel has a minimum yield strength of 30 ksi and a minimum tensile strength of 75 ksi.

This stainless steel grade is routinely stocked in various formats, including: 304 stainless steel sheet, 304 stainless steel plate, 304 stainless steel tube, and 304 stainless steel bar.

What is 304 stainless steel sheet?

304 stainless steel sheet is a commonly used grade of stainless steel that belongs to the austenitic family of stainless steels. It is also known as 18/8 stainless steel because it contains approximately 18% chromium and 8% nickel by weight. The alloy composition of 304 stainless steel provides excellent corrosion resistance, high durability, and good formability.

Here are some key features and properties of 304 stainless steel sheet:

1. Corrosion resistance: 304 stainless steel exhibits excellent resistance to corrosion in various environments, including atmospheric conditions and mild chemical environments. It is particularly resistant to oxidation and corrosion by most organic and inorganic acids.
2. Strength and durability: While not as strong as some other stainless steel grades like 316, 304 stainless steel still offers good tensile strength and durability. It maintains its strength and integrity even at elevated temperatures.
3. Formability and weldability: 304 stainless steel is highly formable, allowing it to be easily fabricated into different shapes and structures. It can be cold worked, bent, or rolled without significantly affecting its mechanical properties. It is also readily weldable using common welding techniques.
4. Hygienic and food-grade suitability: Due to its corrosion resistance and easy cleaning properties, 304 stainless steel is widely used in applications where hygiene and cleanliness are important, such as in food processing equipment, kitchen appliances, and medical devices.
5. Appearance and finish: 304 stainless steel has a bright, reflective surface finish, often referred to as a “brushed” or “mill” finish. It provides an attractive aesthetic appearance and can be further polished or coated for specific applications.

304 stainless steel sheet finds diverse applications in various industries, including:

• Construction: Roofing, cladding, architectural trim, and decorative applications.
• Kitchenware and appliances: Sinks, countertops, utensils, and appliances.
• Food processing: Equipment, storage tanks, and piping systems.
• Automotive: Trim, exhaust systems, and components.
• Chemical processing: Tanks, valves, and fittings.
• Medical and pharmaceutical: Surgical instruments, implants, and laboratory equipment.

It’s important to note that 304 stainless steel is not suitable for applications involving exposure to highly corrosive environments or high temperatures, where higher-grade stainless steels like 316 or 321 may be more appropriate.

Are 340 and 430 stainless steel ferritic, austenitic, or martensitic?

Stainless steel can be classified into three common categories — austenitic, ferritic, and martensitic.

Austenitic steel is the most common. It has a relatively high chromium content, making it especially corrosion-resistant and non-magnetic (although it may become magnetic after cold working).

Ferritic metals are the second most common category. These steels are less expensive than austenitic steels due to their lower nickel content. They are magnetic and can be hardened through cold working.

Martensitic stainless steel is the least common category of stainless steel. Although it is the hardest and most durable kind of stainless steel, martensitic metals are the least corrosion-resistant. Martensitic stainless steels are increasingly found in the automotive industry.

Type 430 stainless steel is ferritic while type 340 stainless steel is austenitic.

Is 430 or 304 grade stainless steel rust proof?

All grades of stainless steel resist corrosion, but grade 304 is particularly rustproof because of its high nickel content. This addition to the alloy makes grade 304 considerably more expensive than grade 430 stainless steel, however.

In general, grade 430 works best for budget-conscious buyers while grade 304 serves buyers with an eye for the long term.

Is 304 or 430 grade stainless steel magnetic?

Austenitic stainless steels are not magnetic. Since grade 304 stainless steel is austenitic, it is not magnetic.

Ferritic stainless steel grades are magnetic. Thus, grade 430 is magnetic. Most kitchen knives are made from the 400 grades of stainless steel, which is why they can be stored on a magnetic strip.

What is the hardness of 430 and 304 stainless steel?

Stainless steel’s hardness is measured by the Brinell Hardness Number (BHN). The BHN is a measure of an alloy’s ability to resist permanent indentation.

Grade 430 stainless steel’s BHN is 183, and grade 304 stainless steel’s BHN is 201. The higher the BHN, the harder the alloy.

Is grade 304 or grade 430 stainless steel better?

Each grade of stainless steel brings its own benefits and drawbacks. In general, grade 304 stainless steel offers more corrosion resistance than grade 430 because of its higher nickel content. The nickel also makes grade 304 easier to draw or press. That same element, however, also raises the price of grade 304 steel.

Put simply, grade 304 offers higher malleability and greater longevity, and grade 430 offers a less expensive steel option.

430 vs 304 stainless steel

• Corrosion Resistance
  • Grade 430 stainless steel provides resistance to corrosion because it contains chromium like all other stainless steel grades.
  • Grade 304 stainless steel offers exceptionally strong corrosion resistance due to the addition of nickel to the alloy.
• Popularity
  • Grade 430 stainless steel is the second most widely used of all stainless steel grades.
  • Grade 304 stainless steel is the most widely used of all stainless steel grades.
• Workability
  • Grade 430 stainless steel can easily be bent, stretched, or drawn but is difficult to weld.
  • Grade 304 stainless steel is easy to weld, press, and stretch. It offers good weldability.
• Magnetism
  • Grade 430 stainless steel is magnetic.
  • Grade 304 stainless steel is not magnetic.
• Food grade stainless steel
  • Grade 304 stainless steel is also known as food-grade stainless steel because it is often used to create the hygienic surfaces needed in the food and beverage industry.

Grades 430 and 304 are the two most common grades of stainless steel. Both offer a durable iron alloy that can resist rust and corrosion. Typically, however, grade 304 provides more corrosion resistance and thus greater longevity than grade 430, which is a more budget-friendly option.

To find out which grade of stainless steel may be right for your project, contact Kloeckner today.