Achieving a superior combination of tensile properties and corrosion resistance in AISI420 martensitic stainless steel by low-temperature tempering.

The mechanical and electrochemical properties of AISI420 martensitic stainless steels (MSS) tempered at different temperatures (200, 400, and 600 ℃) are systematically investigated. The increased tempering temperature leads to the decreased strength, while the elongation remains relatively stable. Notably, the MSS tempered at 200 ℃ exhibits a superior strength-ductility synergy, featuring a strength of 1.65 GPa, and elongation of 10%. Moreover, increasing tempering temperature reduces the electrochemical properties and pitting corrosion resistance. In the tempered samples, pitting corrosion initiates near the inclusions and carbides, with the Cr-rich carbides and Cr-depleted regions serving as channels that promote the propagation of corrosion. • The AISI420 steel tempered at 200 ℃ showed the highest tensile strength and ductility. • Increasing tempering temperature reduces the pitting corrosion resistance. • Pitting preferentially initiates near the inclusions and Cr-rich carbides. • High density carbides at higher tempering temperature promote pitting propagation. [ABSTRACT FROM AUTHOR]