Effect of martensite morphologies on corrosion in sea water of X52 dual phase steel

This study investigates the effect of martensite morphologies on the corrosion behavior of X52 dual-phase steel when exposed to seawater. The steel underwent three different heat treatments: direct quenching (DQ), step quenching (SQ), and intermediate quenching (IQ) at 760°C and 800°C, in order to achieve varying martensite structures. The direct quenching (DQ) treatment resulted in the formation of fine martensite, evenly distributed throughout the ferrite matrix. The intermediate quenching (IQ) treatment led to the formation of martensite along the ferrite/ferrite grain boundaries. In contrast, the step quenching (SQ) treatment produced a banded morphology of martensite and ferrite. We studied the corrosion behavior using Tafel polarization techniques in a saltwater solution. We observed that the morphology and quantity of martensite influence the corrosion behavior. The corrosion rate of the direct quenching (DQ) treatment was lower compared to that of the step quenching (SQ), intermediate quenching (IQ), and the initial untreated state.