Effect of Heat Treatment on the Properties of a High Alloying Maraging Steel Fabricated by Laser Metal Deposition

Traditional maraging steels are not able to satisfy the development of modern industry. Optimizing the properties of maraging steels is now a fascinating field. In this paper, a novel high alloying element maraging steel (HA-MS1) is successfully prepared by laser metal deposition (LMD). Then differential scanning calorimetry (DSC) phase transformation analysis on the as-deposited (AF) specimens was conducted and the reasonable aging heat treatment (AT) and solution + aging heat treatment (ST + AT) were subsequently proposed. These specimens were characterized by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), hardness test, wear test and potentiodynamic polarization test for microstructure, phase, hardness, tribological and corrosive properties. The grain refinement and a large number of Ni₃(Ti, Mo) intermetallic compounds in the matrix after AT resulted in superior hardness and wear resistance, while leading to poor corrosion resistance. Thereinto, specimens subjected to 460 °C AT possessed the ideal hardness and wear resistance of 638 HV and 1.75 \(\times\) 10⁻⁶ mm³/Nm, respectively, with an increase of 68% and 118% compared to the as-deposited specimens. The austenite (\(\gamma\)) content of the ST + AT specimens increased drastically, reaching 23.1% for the 820 °C ST + 460 °C AT specimens. This phenomenon resulted in a decreasing compatibility of mechanical properties than the AT specimens, but the specimens aged at 490 °C after solution treatment at 820 °C had the best corrosion resistance, mainly due to their good surface and more densification.