What are the differences between stainless steel 304, 304L, 316, and 316L?

The difference between 304 and 304

There are certain differences between 304 and 304L in terms of composition, performance and use. Especially in terms of carbon content, 304L is an ultra-low carbon stainless steel with a carbon content reduced to less than 0.03%. On the basis of improving the corrosion resistance of stainless steel, it can also improve the corrosion resistance of 304 caused by the precipitation of chromium carbide between 450 and 860°C. Intergranular corrosion caused by sensitization and welding, and 304L has better welding performance. Of course, the price of 304L is also relatively high; but it is worth noting that neither 304 nor 304L is resistant to corrosion by media containing chloride ions. It needs to be selected according to the specific usage scenario.

The difference between 316 and 316L

There are certain differences in composition and performance between 316 and 316L. 316 has a higher carbon content, while 316L has a lower carbon content. In addition, 316L has better corrosion resistance and oxidation resistance than 316, and can maintain good corrosion resistance even in marine environments. In addition, due to its low carbon content, 316L has good welding performance and is suitable for multi-layer welding. It generally does not require heat treatment after welding;

In summary, they each have their own characteristics in terms of composition and performance. The most suitable material needs to be selected based on the specific requirements and conditions of the application.

How to choose between 304 and 316?

304 and 316 stainless steel are common and the most widely used stainless steel. In general corrosion-resistant environments, 304 has better cost performance and a relatively low unit price. However, when the usage scenario has higher requirements for chloride ion corrosion resistance and heat resistance, 316 needs to be selected. Because in addition to chromium and nickel, 316 also contains 2-3% molybdenum. Molybdenum can effectively improve the chloride corrosion resistance, high temperature strength and creep performance of stainless steel. In summary, if you need a material with better corrosion resistance and oxidation resistance, you can choose 316, but of course you have to bear its high price. If your usage requirements are not too high, 304 is also a good choice.