Heat treatment of additively manufactured maraging steel
Additive technologies belong to advanced methods of metal processing, which enable production of relatively complex shapes of the products without special tooling and with minimal material losses. Due to a specific thermal conditions, additively produced parts possess not only special microstructures but also significant residual stresses. This is the reason why post processing heat treatment is strongly recommended to adjust the microstructure and thus improve mechanical properties and decrease residual stresses. The basic methods of post processing heat treatment of additively manufactured maraging steel will be presented in this contribution and their effect on the final microstructure and mechanical properties will be described. Additive manufacturing of maraging steel produced very fine cellular microstructure with retained austenite at cell boundaries, which reached the ultimate tensile strength of 1100 MPa and total elongation of 11%. The post processing heat treatment resulted in partial or full dissolving of the original cellular microstructure and due to various intensity of precipitation, the tensile strengths reached 1050 MPa -2100 MPa and total elongations 5% – 15%.