304 Or 316 Stainless Steel

304 and 316 stainless steel, we should always see in the industry, in the LED flood lighting, also use 304 and 316 stainless steel as the bracket of the lamp. Which is better 304 or 316 stainless steel?

What is 304 stainless steel?

Grade 304 stainless steel is generally regarded as the most common austenitic stainless steel. It contains high nickel content that is typically between 8 and 10.5 percent by weight and a high amount of chromium at approximately 18 to 20 percent by weight. Other major alloying elements include manganese, silicon, and carbon. The remainder of the chemical composition is primarily iron.

The high amounts of chromium and nickel give 304 stainless steel excellent corrosion resistance. Common applications of 304 stainless steel include:

  • Appliances such as refrigerators and dishwashers
  • Commercial food processing equipment
  • Fasteners
  • Piping
  • Heat exchangers
  • Structures in environments that would corrode standard carbon steel.

What is 316 stainless steel?

Similar to 304, Grade 316 stainless steel has high amounts of chromium and nickel. 316 also contains silicon, manganese, and carbon, with the majority of the composition being iron. A major difference between 304 and 316 stainless steel is the chemical composition, with 316 containing a significant amount of molybdenum; typically 2 to 3 percent by weight vs only trace amounts found in 304. The higher molybdenum content results in grade 316 possessing increased corrosion resistance.

316 stainless steel is often considered one of the most suitable choices when selecting an austenitic stainless steel for marine applications. Other common applications of 316 stainless steel include:

  • Chemical processing and storage equipment.
  • Refinery equipment
  • Medical devices
  • Marine environments, especially those with chlorides present

What’s the difference between 304 and 316 stainless steel? 

The simple answer is 304 contains 18% chromium and 8% nickel while 316 contains 16% chromium, 10% nickel and 2% molybdenum. The molybdenum is added to help resist corrosion to chlorides (like sea water and de-icing salts).

304 stainless steel is a versatile stainless steel material. High temperature resistance is also good, the general use temperature limit is less than 650 °C. 304 stainless steel has excellent stainless corrosion resistance and good resistance to intergranular corrosion.

 316 stainless steel, 18Cr-12Ni-2.5Mo Because of the addition of Mo, it has excellent corrosion resistance, atmospheric corrosion resistance and high temperature strength. It can be used under harsh conditions; it has excellent work hardening property (non-magnetic).

Grade 316 is the standard molybdenum-bearing grade, second in importance to 304 amongst the austenitic stainless steels. The molybdenum gives 316 better overall corrosion resistant properties than Grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments.

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