Finite element model for the description of intrinsic heat treatment induced aging in 18Ni300 maraging steel during direct laser powder deposition

Rodrigues, Ivan; Moita de Deus, Augusto; Figueiredo-Pina, Célio Gabriel; Almeida, Amélia

Key information

Authors:

Rodrigues, Ivan (Ivan Diogo Mendonça Rodrigues); Moita de Deus, Augusto (Augusto Manuel Moura Moita de Deus); Figueiredo-Pina, Célio Gabriel; Almeida, Amélia (Maria Amélia Martins de Almeida)

Published in

September 2, 2026

Abstract

Laser additive manufacturing techniques have received in recent times increased attention in the case of the production of customized, high-value components from high-strength, age-hardenable maraging steels. These alloys require cooling to form a carbon-free lath martensite (α′) phase that is then age-strengthened through precipitation at approximately 480 °C. Homogenization and aging are currently accomplished through costly post-manufacturing heat treatments that can, in principle, be replaced by the intrinsic heat treatment (IHT) effect of additive manufacturing, caused by repeated localized heating of the workpiece. This work aims to estimate the precipitation hardening time experienced by a thin wall of maraging steel during additive laser powder deposition at the rate of 1 single track overlap per minute and a unidirectional laser travel speed of 10 mm/s. For this, a heat transfer finite element deposition model is developed from in-situ workpiece temperature measurements and then the local thermal histories are used to interpret the microhardness profiles of such thin walls. The model can estimate the intrinsic aging time by considering a 380–580 °C aging temperature range found through differential thermal analysis. The hardness in the as-built condition and the estimated intrinsic aging time fit the established early-stage hardening kinetics law exponent for maraging steels, thereby validating the intrinsic age-hardening conditions that led to the IHT aging in thin walls.