Corrosion Behavior of Super Austenitic Stainless Steel 904L Weldment in Sulfuric Acid Media Used for Leaching Application

摘要

This article reports the corrosion behavior of 904L weldment in sulfuric acid as a strong corrosive media. The corrosion behavior was studied by total immersion tests and potentidynamic polarization test. Total immersion test has been conducted at different acid concentrations typically: 1, 2, 4, 6, 8 and 18.4 M at 25oC. The effect of temperature (25- 100oC) on the weight loss measurements of the alloy samples was followed in the 4 M acid solution. On the other hand, potentiodynamic polarization tests were conducted in 2,5, 8 and 18.4 M H_2SO_4 solution. The potentiodynamic polarization test was also conducted in the practically used leaching medium (2 M H_2SO_4 + 10% monazite). Results show that the weight loss increases with the increase of acid concentration and reaches its maximum at 4 M H_2SO_4 and then gradually decreases. Meanwhile, the rise in temperatures results in the increase of weight loss. Potentiodynamic polarization tests indicate that the 5 M acid solution gives the highest corrosion rate of 0.6399 mm/Y. The leaching medium shows relatively higher corrosion rate (0.124 mm/y) than the corresponding 2 M H_2SO_4 without monazite (0.01712 mm/y).