Stainless steel 304, 304H, 304L difference

Stainless steel 304, 304H, 304L difference

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

Chemical component

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

The H in 304H refers to high temperature, high carbon content is the guarantee of high temperature resistance, austenitic steel above 525 degrees Celsius, carbon content is not less than 0.04%, high temperature strength is better than pure austenite.

Mechanical property

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 for different uses are also different.