Influence of Ausforming on the Micro‐ and Nanostructure of PH 13‐8 Mo Maraging Steels

Abstract

Herein, the potential of using the thermomechanical treatment ausforming to optimize the microstructure of PH 13‐8 Mo maraging steels is investigated. Of particular interest are the effects on the formation of β‐NiAl precipitates and reverted austenite during subsequent aging. Ausforming experiments at deformation temperatures of 400 and 600 °C and strains of 40% and 70% are conducted using a deformation dilatometer. Afterward, the samples are subjected to aging at temperatures varying from 482 to 593 °C. This is followed by a thorough microstructural characterization ranging from light optical microscopy to X‐Ray diffraction and atom probe tomography. The results demonstrate that ausforming effectively refines the microstructure, resulting in a significant increase in hardness. Moreover, it is revealed that the ausforming parameters have a noticeable influence on the number density of β‐NiAl precipitates and the amount of reverted austenite. A well‐balanced microstructure containing relatively fine precipitates and a high amount of reverted austenite can be achieved by ausforming at 600 °C with 40% strain. Overall, the results prove a promising potential of ausforming for PH 13‐8 Mo maraging steels with regard to tailoring optimized microstructures, which could ultimately benefit the aerospace industry where these alloys are used.