In fact, the content of chromium nickel is 304 stainless steel, the composition is 18% chromium (Cr), 8% nickel (Ni), but the main difference lies in the carbon content.
Chemical composition (%) of 304, 304L and 304H
304L is ultra-low carbon stainless steel with carbon content below 0.03%, which can avoid intercrystalline corrosion. Theoretically, the anti-stress corrosion 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 321 process of adding titanium is more expensive, with thick steel and high price.
304 H in H refers to the high temperature, high carbon content is the guarantee of high temperature strength, austenitic steel used in GB150 requirements above 525 degrees, the carbon content is not less than 0.04%, carbide is strengthening phase, especially the high temperature strength is superior to the pure austenite.
Of the three, the highest carbon content is 304H, and the lowest carbon content is 304L, while the carbon content of 304 stainless steel is between them.The higher the carbon content, the worse the corrosion resistance of stainless steel is.The different carbon content will also lead to the price difference, or the use of that sentence will be different requirements.
Mechanical performance table of 304, 304L and 304H