Corrosion Resistance Analysis of 316L Tube Sheet

The addition of molybdenum (2-3%) in 316L tube sheets significantly enhances their pitting corrosion resistance in chloride environments. With a PREN value ≥25, they can resist corrosion from seawater and weakly acidic media. The austenitic structure, after solution treatment, dissolves carbides, reducing susceptibility to intergranular corrosion.

In petrochemical applications, 316L tube sheets can withstand 10% sulfuric acid and alkaline solutions below 50°C. However, high-temperature concentrated sulfuric acid (≥60°C) can lead to selective grain boundary corrosion. The interpass temperature in the welding zone should be controlled ≤150°C to avoid σ phase precipitation.

In practical applications, cathodic protection or passivation treatment (such as nitric acid passivation) should be used in conjunction. In Cl⁻-containing media, it is recommended to limit the operating temperature ≤60°C, otherwise stress corrosion cracking (SCC) is likely to occur.