What Is The Difference Between 304, 304L, 316, and 316L?

Stainless steel is a type of steel. Steel refers to steel containing less than 2% of carbon (C), and more than 2% is iron. The addition of chromium (Cr), nickel (Ni), manganese (Mn), silicon (Si), titanium (Ti), molybdenum (Mo), and other alloying elements during the smelting process improves the performance of the steel and makes the steel more resistant to corrosion. (that is, not rusted) is what we often call stainless steel.

What is stainless steel?

What exactly are "steel" and "iron", what are their characteristics, and what is their relationship? How did the 304, 304L, 316, and 316L we usually call come from, and what are the differences between them?

  • Steel: A material with iron as the main element, carbon content generally below 2%, and other elements.

  • Iron: A metallic element with atomic number 26. Iron materials have strong ferromagnetism, good plasticity and thermal conductivity.

  • Stainless steel: resistant to weak corrosive media such as air, steam, and water, or stainless steel. The commonly used steel grades are 304, 304L, 316, 316L, which are 300 series steels of austenitic stainless steel.

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Why do stainless steels have different steel grades?

In the smelting process of stainless steel, due to the different varieties of alloying elements added, the amount of addition of different varieties is different. Their characteristics are also different. In order to distinguish them, they are crowned with different steel grades. The following is a table of "alloying elements" content of different steel grades of common decorative stainless steels for reference only:

Chemical Composition (Mass Fraction, %) GradeCSiMnPSCrNi

Performance introduction of stainless steels

304 stainless steel

304 stainless steel is the most common type of steel. As a widely used steel, it has good corrosion resistance, heat resistance, low temperature strength and mechanical properties; good hot workability such as stamping and bending, and no heat treatment hardening (non-magnetic, then use the temperature -196 ℃ ~ 800 ℃).

  • 304L stainless steel

As a low-carbon 304 steel, its corrosion resistance is similar to that of 304 steel under normal conditions, but after welding or after stress relief, its resistance to grain boundary corrosion is excellent; it can also remain good without heat treatment. High corrosion resistance, operating temperature -196℃~800℃.

  • 316 stainless steel

316 stainless steel has excellent corrosion resistance, atmospheric corrosion resistance and high temperature strength due to the addition of molybdenum, and can be used under harsh conditions; excellent work hardening (non-magnetic).

  • 316L stainless steel

As a low carbon series of 316 steel, in addition to having the same characteristics as 316 steel, its resistance to grain boundary corrosion is excellent.