Wear and corrosion behavior of 18Ni-300 maraging steel produced by laser-based powder bed fusion and conventional route

Abstract

Maraging steels such as 18Ni-300 (1.2709) are characterized by high yield and tensile strength together with good toughness making them interesting materials for aerospace, automotive and tooling sectors as well as for bearing gears parts. The low carbon martensite matrix combined with the nanosized intermetallic precipitates are responsible for the peculiar mechanical properties. Thanks to the very low carbon content, these steels are easily weldable and therefore suitable for additive manufacturing (AM) techniques, such as laser-based powder bed fusion (LPBF). Indeed, this technique was recently adopted in tooling and molding industry to produce inserts with conformal cooling channels capable to improve inserts and cores lifetime enhancing productivity. These types of components usually undergo severe stress conditions, wear phenomena and even aggressive environments.This work aims at comparing the tribological and corrosion behaviour of 1.2709 maraging steel samples produced by both forging and LPBF technique. Conventional samples were investigated after solution annealing and aging treatment while AM samples were directly aged. Aging parameters were chosen to achieve the same hardness values for both the production conditions. Samples sliding wear behaviour was investigated through pin-on-disc tests using 100Cr6 steel ball as counterpart (ASTM G99) at three different sliding velocities, while potentiodynamic polarization measurements (ASTM G3) were conducted in 3.5 wt % NaCl solution.Microstructural analyses and hardness measurements were carried out on as-aged samples. The corrosion damage and the wear mechanism were investigated by means of scanning electron microscope (SEM). For the considered heat treatment, results show only small differences on the wear and corrosion behaviors between forged and AM samples, despite differences in the microstructural morphology, demonstrating the reliability of AM components.