Microstructure and Property Modification of High-Strength Martensitic Steel Through Plasma Arc Remelting

The microstructure of high-strength martensitic steel specifically made for additive manufacturing was modified via in situ plasma arc remelting (PAR) to improve its surface properties. The results reveal that the microstructure is characterized by the intragranular martensite and intergranular eutectic structure of high-strength martensitic steel. The intragranular worm-like δ-ferrite embedding in the martensite matrix was clearly observed after PAR. Compared with the as-deposited part, the tensile strength of the PAR part reached 1753 MPa, and the ductility increased to 2.3%. The strength and elongation had increased by 20% and 229%, respectively. After in situ PAR, the wear loss decreased to 80% of the tailored high-strength martensitic steel, and the corrosion current density decreased to 17%. Both the as-deposited part and the PAR part exhibited significant intergranular corrosion morphological characteristics.