The mechanical properties and the corrosion resistance of additively manufactured stainless steels are influenced by their alloy composition, processing and heat treatment. In the case of components that are manufactured using powder bed fusion, the initial state after 3D-printing is crucial in order to adjust the mechanical properties and corrosion resistance through the subsequent heat treatment. This applies in particular to the high-alloy, high-strength and corrosion-resistant maraging steel 1.4542 (X5CrNiCuNb16-4), which is used in the aerospace industry. The alloy concept of this steel will be presented in the lecture, followed by the properties of 3D-printed components and the effect of further heat treatments. It is shown that a subsequent heat treatment can achieve tensile strengths of up to 1.500 MPa and notch impact values of up to 50 J. To analyse the structure-property-relationship, the fracture surfaces of the notched bar impact test and the corresponding microstructure are analysed by light and scanning electron microscopy. The pitting corrosion resistance is also determined using potentiodynamic polarization tests. All results are compared to classic austenitic stainless steels 1.4404 (316L) in order to fully reflect the property profile. The extensive results show that the maraging steel 1.4542 (X5CrNiCuNb16-4) is an excellent material for 3D printing by powder bed fusion and achieves outstanding properties by suitable heat treatment. The heat treatment allows to adept the material properties of the maraging steel 1.4542 (X5CrNiCuNb16-4) to the specific requirements of different applications.