3D printing technology is increasingly being applied to make parts based on metal materials such as AISI H13 steel for industrial application. Structure and properties of the printed part depend strongly on the input parameters such as material, printing technology, and especially post-printing processes such as heat and surface treatment.

In this study, the AISI H13 steel samples were 3D printed using a Selective Laser Melting system (AL-METAL 250, Alpha Laser, Germany). The printed samples were then annealed at different temperatures in the range 860 ^oC - 1020 ^oC for 4 h. The samples were further heated and gas quenched from 1030 ^oC using vacuum furnace and tempered three times at 585 ^oC / 5 h in heat treatment furnace using N₂ as the protecting gas. The microstructure and properties of the annealed samples were investigated using optical microscopy, x-ray diffractometry, and hardness testing.

The results show that the as-built AISI H13 steel sample has a microstructure consisting of ferrite/martensite and Cr₇C₃ phases and a small amount of MoC/VC carbide. The higher annealing temperature, the larger martensite decomposition, and the more coarse carbide precipitated. After the quenching process, the microstructure mainly includes the martensite, residual austenite, and carbide phases and the hardness is lower than that of the as-built sample possibly due to a large amount of residual austenite. The tempering has also an impact on the hardness possibly due to a second hardness phenomenon. Based on these results further investigation, e.g. surface treatment by nitriding to reach high surface hardness, will be performed.