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There are several distinct grades of stainless steel. Each grade has its own distinct tensile strength, chemical composition, and other qualities. Let's examine two of the most widely used stainless steel grades, SAE 430 and SAE 304 stainless steel.

What is the Difference Between SAE 304 and SAE 430?

SAE 304 austenitic stainless steel is the most versatile type of stainless steel across various industries. It contains up to 0.08% of carbon, between 18% and 20% chromium content, and between 8% and 10.5% of nickel by weight. The rest of the alloy is balanced out with the base material, iron.

SAE 304 stainless steel composition also has stabilizing elements that provide the steel with numerous mechanical properties. The SAE 430 differs in its carbon content and the lack of stabilizing elements, such as nickel. With 0.12% carbon, stainless steel 430 is a relatively high-carbon steel.

Another distinction is the chromium content, which is approximately 2-4% lower in 430 compared to SAE 304. This element provides both stainless steel grades with their corrosion resistance by preventing the oxidation of iron within the alloy. But the biggest distinction is the low nickel content that tops out at 0.75%.

The lack of stabilizing elements makes SAE 430 exceptionally difficult to weld.

Molecular Structure

SAR 304 is austenitic stainless steel, meaning that it has a high chromium content, which makes it especially corrosion-resistant and non-magnetic. However, its non-magnetic properties can be disrupted if the material of formed using cold working methods.

SAE 430 is ferritic stainless steel with relatively high chromium content but very low nickel content. This molecular structure makes stainless steel magnetic and allows strengthening by cold working.

Corrosion Resistance

Stainless steel generally offers good corrosion resistance, but some grades are less susceptible to corrosion than others. The higher nickel content in SAE 304 makes this type of steel more corrosion-resistant than SAE 430. So, in applications in which cost is a larger factor than functionality, SAE 430 would be the right choice.

If you're applications simple corrosive environments, then perhaps SAE 304 would offer better corrosion resistance. However, if you're dealing with chemically corrosive environments, you should consider using SAE 316. It has a higher molybdenum content that prevents chemical corrosion by acids and alkalis.

SAE 430 is used more for cosmetic purposes, like automotive trims or bathroom decorations.

Hardness

Hardness, measured by the Brinell Hardness Number, determines the material's resistance to deformation and abrasion. SAE 304 measures 201 on the BHN scale, while SAE 430 stainless steel scores 183 on the BHN scale. This means that the SAE 304 is a harder grade of stainless steel.

Weldability and Formability

Due to the higher nickel content within the alloy, SAE 304 is easier to weld, press, or stretch, which can't be said for the SAE 430. However, the latter is easily bent, drawn, or stretched.

Choosing Stainless Steel Grades for Your Application

In summary, SAE 430 and SAE 304 are considerably different grades of stainless steel, as they belong to different alloy types. The former belongs to chromium alloys, while the latter belongs to chromium-nickel alloys.

If you want to learn more about stainless steel, visit our Engineer Resource Guides or simply browse for stainless steel hardware and fixtures online.