Effect of Microstructure of Low-Alloy Steel on Corrosion Propagation in a Simulated CO₂ Environment

The paper focuses on the analysis of initiation and propagation CO 2 corrosion in several samples low-alloy steel with different microstructures using scanning electrochemical microscopy (SECM) other techniques. It is found that rate mode are highly sensitive to microstructure. overall current density much higher more uniformly distributed for tempered martensite structure than having either a ferritic-pearlitic microstructure or combining ferritic, bainitic martensitic-austenitic regions. As result, sample undergoes uniform corrosion, while two undergo selective corrosion. SECM maps show regions polygonal ferrite generate larger anodic currents pearlitic early stages residual cementite provides greater cathodic surface areas after initial dissolution ferritic lamellae within pearlite, promoting galvanic subsequently enhanced lamellae. According data, iron grains 2.4 times faster