In Situ Observations of the Microstructural Evolution during Heat Treatment of a PH 13-8 Mo Maraging Steel

Andreas Rosenauer, Dominik Brandl, Gerald Ressel, Sarah Lukas, Christian Gruber, Martin Stockinger, Ronald Schnitzer

Publikation: Beitrag in FachzeitschriftArtikelForschungBegutachtung


The standard heat treatment of PH 13-8 Mo maraging steels consists of solution annealing and subsequent aging. Herein, it is investigated how an additional intercritical annealing step prior to aging affects the microstructure, and, consequently, the mechanical properties of a PH 13-8 Mo maraging steel. In situ techniques by means of high-temperature electron backscatter diffraction and high-temperature X-ray diffraction are applied to study the microstructural changes during intercritical annealing and subsequent aging. In addition, high-resolution investigation methods, such as transmission electron microscopy and atom probe tomography supplemented by transmission Kikuchi diffraction, are used for an in-depth characterization of the microstructure. The results reveal that a diffusion-controlled martensite to austenite transformation accompanied by partitioning of the substitutional atoms Cr, Ni, and Mo takes place during intercritical annealing. As a result of partitioning during intercritical annealing, an inhomogeneous distribution of Ni remains in the microstructure after the martensitic transformation. Consequently, the formation of reverted austenite is facilitated during subsequent aging due to existing Ni-enriched zones in martensite. Since the fracture toughness is significantly enhanced compared to the standard heat treatment, it is suggested that this improvement is related to the increased phase fraction of reverted austenite.

Fachzeitschrift Advanced engineering materials
Frühes Online-Datum17 Apr. 2023
PublikationsstatusVeröffentlicht - Juni 2023

Bibliographische Notiz

Funding Information:
The authors gratefully acknowledge the financial support under the scope of the COMET program within the K2 Center “Integrated Computational Material, Process and Product Engineering (IC‐MPPE)” (Project No 886385). This program is supported by the Austrian Federal Ministries for Climate Action, Environment, Energy, Mobility, Innovation and Technology (BMK) and for Digital and Economic Affairs (BMDW), represented by the Austrian Research Promotion Agency (FFG), and the federal states of Styria, Upper Austria, and Tyrol.

Publisher Copyright:
© 2023 The Authors. Advanced Engineering Materials published by Wiley-VCH GmbH.

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