Many people are not very clear about the specific material classification of stainless steel. The following is a precautionary explanation for the subtle difference of stainless steel 304 material by Prevo Valve Technology Department, hoping to solve your confusion:

In fact, the content of chromium and nickel is 304 stainless steel, and the ingredients are all containing 18% chromium (Cr) and 8% nickel (Ni), but the main difference is the difference in carbon content.

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

H in 304H refers to high temperature, and high carbon content is the guarantee of high temperature strength. When GB150 requires austenite steel to be used above 525 degrees, the carbon content is not less than 0.04%. The carbide is the strengthening phase, especially the high temperature strength Better than pure austenite.

Among the three, the highest carbon content is 304H, the lowest carbon content is 304L, and the carbon content of 304 stainless steel is between the two. The higher the carbon content, the worse the corrosion resistance of stainless steel and the easier it is to rust. The difference in carbon content also causes the price to be different, and the requirements are different for different uses