Corrosion resistance of 904L stainless steel plate

Since the carbon content of 904L stainless steel plate is very low, max. up to 0.020%, there is no carbide precipitation under normal heat treatment and welding conditions. This eliminates the risk of intergranular corrosion occurring after general heat treatment and welding. Because of the high content of chromium, nickel and molybdenum and the addition of copper, 904L stainless steel plate can be passivated even in reducing environments, such as sulfuric acid and formic acid.

High nickel content also has a lower corrosion rate in the active state. In the concentration range of 0~98%, in pure sulfuric acid, the temperature of 904L stainless steel plate can be as high as 40 degrees Celsius. The corrosion resistance of pure phosphoric acid in the range of 0~85% concentration is very good. Impurities in industrial phosphoric acid produced by wet process have a strong effect on corrosion resistance. In all kinds of phosphoric acid, the corrosion resistance of 904L stainless steel plate is better than that of ordinary stainless steel. In strong oxidizing nitric acid, the corrosion resistance of 904L stainless steel plate is lower than that of high alloy steel without molybdenum.

In hydrochloric acid, the use of 904L stainless steel plate is limited to a lower concentration of 1-2%. In this concentration range, the corrosion resistance of 904L stainless steel plate is better than that of conventional stainless steel. 904L stainless steel plate has high resistance to spot corrosion. In chloride solution, its ability to resist crevice corrosion is also good. The high nickel content of 904L stainless steel plate decreases the corrosion rate at the pit and gap. Ordinary austenitic stainless steels may be sensitive to stress corrosion in a chloride-rich environment at temperatures above 60 degrees Celsius, which can be reduced by increasing the nickel content of the stainless steel. Because of the high nickel content, 904L stainless steel plate has high resistance to stress corrosion cracking in chloride solution, concentrated hydroxide solution and hydrogen sulfide rich environment.