TY - JOUR

T1 - Influence of increasing chromium content on additively manufactured tool steels

T2 - Microstructural and mechanical evolution before and after heat treatment

AU - Ofner, Nicole

AU - Bodner, Sabine

AU - Kunnas, Peter

AU - Asci, Atacan

AU - Kutlesa, Kevin

AU - Stark, Andreas

AU - Höbenreich, Philipp

AU - Aumayr, Christin

AU - Wu, Liang

AU - Turk, Christoph

AU - Keckes, Jozef

AU - Meindlhumer, Michael

PY - 2024/12/21

Y1 - 2024/12/21

N2 - The demand for high performance materials and tailored alloys is increasing within the additive manufacturing (AM) community. Therefore, this study investigates and explores the influence of increasing Cr content on the microstructure and mechanical properties of martensitic tool steels suitable for AM processing. The analysis covers both the as-built (AB) and heat-treated (HT) conditions, where the latter includes austenitization, quenching and multiple tempering steps. Thus, three Cr-alloyed tool steels, named Alloy A (20 wt% Cr), Alloy B (22 wt% Cr), and Alloy C (24 wt% Cr), were analyzed in the AB and HT conditions. Comprehensive microstructural characterization techniques, including optical microscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy unveiled a clear correlation between the Cr content and the resulting microstructural features and phase occurrences. An in situ synchrotron experiment identified the body-centered cubic-Fe phase in the alloys exclusively as δ-ferrite. Increasing the Cr content resulted in a higher amount of δ-ferrite in both the AB and HT conditions, which consequently reduced the amount of martensite after heat treatment. Mechanical properties, evaluated through Vickers hardness and tensile testing, revealed a decrease in hardness and tensile strength accompanied by a change of the deformation behavior from brittle to ductile with increasing Cr content and consequently increased δ-ferrite content. This study thus contributes to a deeper understanding of the effects of increasing Cr content on the microstructural characteristics, phase occurrence and mechanical properties of high Cr-alloyed tool steels produced via additive manufacturing.

AB - The demand for high performance materials and tailored alloys is increasing within the additive manufacturing (AM) community. Therefore, this study investigates and explores the influence of increasing Cr content on the microstructure and mechanical properties of martensitic tool steels suitable for AM processing. The analysis covers both the as-built (AB) and heat-treated (HT) conditions, where the latter includes austenitization, quenching and multiple tempering steps. Thus, three Cr-alloyed tool steels, named Alloy A (20 wt% Cr), Alloy B (22 wt% Cr), and Alloy C (24 wt% Cr), were analyzed in the AB and HT conditions. Comprehensive microstructural characterization techniques, including optical microscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy unveiled a clear correlation between the Cr content and the resulting microstructural features and phase occurrences. An in situ synchrotron experiment identified the body-centered cubic-Fe phase in the alloys exclusively as δ-ferrite. Increasing the Cr content resulted in a higher amount of δ-ferrite in both the AB and HT conditions, which consequently reduced the amount of martensite after heat treatment. Mechanical properties, evaluated through Vickers hardness and tensile testing, revealed a decrease in hardness and tensile strength accompanied by a change of the deformation behavior from brittle to ductile with increasing Cr content and consequently increased δ-ferrite content. This study thus contributes to a deeper understanding of the effects of increasing Cr content on the microstructural characteristics, phase occurrence and mechanical properties of high Cr-alloyed tool steels produced via additive manufacturing.

KW - Additive manufacturing

KW - tool steels

KW - Chromium content

KW - δ-ferrite

KW - Microstructure

KW - Phase occurrence

KW - Mechanical properties

U2 - 10.1016/j.jmrt.2024.12.169

DO - 10.1016/j.jmrt.2024.12.169

M3 - Article

VL - 34.2025

SP - 2715

EP - 2727

JO - Journal of Materials Research and Technology

JF - Journal of Materials Research and Technology

SN - 2238-7854

IS - January-February

ER -