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

In fact, the content of chromium nickel is 304 stainless steel, which contains 18% chromium (CR) and 8% nickel (Ni), but the main difference is the difference of carbon content.

304L is an ultra-low carbon stainless steel with carbon content less than 0.03%, which can avoid intergranular corrosion. In theory, the effect of stress corrosion resistance is stronger than 304, but the effect is not obvious in practical application. The purpose of reducing carbon is the same as adding titanium, but the smelting cost of 321 with titanium 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 austenitic steel is used above 525 ℃, the carbon content is not less than 0.04%, and carbide is the strengthening phase, especially the high temperature strength is better than pure austenite.

Among them, 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 is, the worse the corrosion resistance of stainless steel is, and the easier it is to rust. Different carbon content also leads to different prices. In other words, different uses and different requirements.