Effect of Manganese Sulfide Inclusion Morphology on the Corrosion Resistance and Pitting Corrosion Behavior of Free-Cutting Austenitic Stainless Steel

The corrosion resistance and pitting corrosion behavior of free-cutting austenitic stainless steels with different contents of sulfur were systematically studied by electrochemical workstation and scanning electron microscope. As the content of sulfur in the steel decreased from 0.270 to 0.089%, the corrosion rate decreased from 10.55 to 2.83 μm/a. The morphologies of manganese sulfide inclusions in the 0.089% S-containing steel were short rod-shaped and globular. The morphologies of manganese sulfide inclusions in the 0.270% S-containing steel were cluster-shaped, long strip-shaped and globular. Various-morphology manganese sulfide inclusions could lead to different degrees of damage to the metal matrix during the process of the pitting corrosion. The order of damage degree from the most to the less was cluster-shaped > long strip-shaped > short rod-shaped.