Effect of thermal treatments on a MAPS-printed Cr–Mo–Ni alloy steel

This study explores the influence of post-processing heat treatments on the microstructure and mechanical properties of a Cr–Mo–Ni alloy steel fabricated via Metal Additive Manufacturing using Powder Sheet (MAPS). Thermo-Calc simulations and differential scanning calorimetry analysis were performed to define solution and tempering conditions. The as-built samples exhibited near-full density and increased carbon content compared to that of feedstock material due to binder decomposition and C pick-up during printing. Austenitizing at 1000 °C followed by water quenching produced a martensitic microstructure with uniform elemental distribution. Subsequent tempering between 200 °C and 600 °C induced carbide precipitation within martensitic laths. X-ray diffraction and electron microscopy analysis confirmed complete carbide dissolution after austenitizing and their re-precipitation during tempering, with finer carbides than those found in the as-built state. Austenitizing and water quenching led to an increase in hardness of 300 HV, while tempering induced a gradual decrease, remaining above the as-built levels up to 400 °C. These results demonstrate that tailored thermal treatments can effectively enhance the mechanical performance of MAPS-printed steels by controlling microstructural evolution.