Pitting corrosion behavior in advanced high strength steels

The type and size of inclusions and their pitting corrosion behavior in dual-phase (DP), transformation-induced plasticity (TRIP), and twinning-induced plasticity (TWIP) steels were investigated. Whereas DP steel had single MnS inclusions, TRIP and TWIP steels had the complex inclusions of MnS and Al2O3, and MnS and Mn oxy-sulfide, respectively. TWIP steel had the most wide size distribution and the largest average size of inclusions. DP steel exhibited the lowest resistance to pitting corrosion due to the high density of inclusions. MnS inclusions in TRIP steel and Mn oxy-sulfide inclusions in TWIP steel acted as a galvanic anode in complex inclusions.