What is the difference between 304, 304H and 304L?

In fact, according to the content of chromium nickel is 304 stainless steel, the composition is containing 18% chromium (Cr), 8% nickel (Ni), but the main difference lies in the different carbon content.

304L is ultra-low carbon stainless steel, the carbon content is reduced to less than 0.03%, can avoid intergranular corrosion, and in theory, the stress corrosion resistance effect is better than 304, but the effect is not obvious in practical application. The purpose of reducing carbon and adding titanium is the same, but the cost of 321 smelting with titanium is higher, the molten steel is thick, and the price is more expensive.

304H H refers to high temperature, high carbon content is the guarantee of high temperature strength, GB150 requirements austenitic steel used in 525 degrees above, carbon content is not less than 0.04%, carbide is strengthening phase, especially high temperature strength is better than pure austenite.

Among the three, the highest carbon content is 304H, the lowest carbon content is 304L, and 304 stainless steel carbon content between the two. The higher the carbon content, the worse the corrosion resistance of stainless steel is, the easier it is to rust. The carbon content also leads to a difference in price, and again, the use of the sentence depends on the requirements.