PSI - Issue 17

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ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Structural Integrity Procedia 00 (2019) 000 – 000

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 17 (2019) 843–849

ICSI 2019 The 3rd International Conference on Structural Integrity Mechanical Properties of 18Ni-300 maraging steel manufactured by LPBF Thomas Simson a, *, Jürgen Koch a , Jakub Rosenthal a , Miloslav Kepka b , Miroslav Zetek b , Ivana Zetková b , Gerhard Wolf c , Petr Tom čík d , Jiři Kulhánek d I SI 2019 The 3rd International onference on Structural Integrity ec a ical r erties f i- ara i steel a fact re ho as Si son a, *, Jürgen Koch a , Jakub Rosenthal a , iloslav epka b , iroslav etek b , Ivana Zetková b , erhard olf c , Petr o čík d , Jiři ulhánek d

a OTH Amberg-Weiden, Kaiser-Wilhelm-Ring 23, Amberg 92224, Germany b University of West Bohemia, Universitní 22, Pilsen 306 14, Czech Republic c Fraunhofer UMSICHT, An der Maxhütte 1, Sulzbach-Rosenberg 92237, Germany d VSB-Technical University of Ostrava, 17. Iistopadu 2172/15, Ostrava-Poruba 708 33, Czech Republic a OTH Amberg-Weiden, Kaiser-Wilhelm-Ring 23, Amberg 92224, Germany b University of West Bohemia, Universitní 22, Pilsen 306 14, Czech Republic c Fraunhofer UMSICHT, An der Maxhütte 1, Sulzbach-Rosenberg 92237, Germany d VSB-Technical University of Ostrava, 17. Iistopadu 2172/15, Ostrava-Poruba 708 33, Czech Republic

Abstract Abstract

The purpose of this document is to investigate the influence of heat treatment on the mechanical properties of parts from MAR 300 (EN 1.2709) produced by LPBF. In order to compare the influence of the heat treatment on the parts properties, some parts were in the state solution annealed and others age hardened tested. For the quality in the LPBF the feedstock powder as starting material is of great importance. Therefore, powder characterization has been performed in order to work out ageing effects after multiple use. As a major ageing effect an increasing oxygen content could be identified which might affect process and parts quality. For industrial acceptance, AM parts need to be produced to the best available tolerances and with well-understood mechanical properties. For this purpose, the mechanical properties of the LPBF samples have been analysed and are compared to those properties for conventional samples. In this investigation, the mechanical tests (hardness test, tensile test and notch impact resistance) have been performed in horizontal and vertical directions of manufacturing by LPBF. The hardness increased from 333~341 HV10 to 640~656 HV10 after heat treatment. Simultaneously, the ultimate tensile strength ( Rm ) increases from 1056~1096 MPa to 1964~2102 MPa, while the break elongation ( ε tot ) is reduced from 11.3~16.0% to 2.0~4.5%. Aged samples show a significant decrease in toughness in the Notch Impact Test. A specifically designed ball joint test setup has shown that the frame manufactured by LPBF provides comparable results as a conventionally manufactured frame and is robust and suitable for the prototype production and test of car headlamps. The purpose of this document is to investigate the influence of heat treatment on the mechanical properties of parts from AR 300 (EN 1.2709) produced by LPBF. In order to compare the influence of the heat treatment on the parts properties, some parts were in the state solution annealed and others age hardened tested. For the quality in the LPBF the feedstock powder as starting material is of great importance. Therefore, powder characterization has been performed in order to work out ageing effects after multiple use. As a major ageing effect an increasing oxygen content could be identified which might affect process and parts quality. For industrial acceptance, A parts need to be produced to the best available tolerances and with well-understood mechanical properties. For this purpose, the mechanical properties of the LPBF samples have been analysed and are compared to those properties for conventional samples. In this investigation, the mechanical tests (hardness test, tensile test and notch impact resistance) have been performed in horizontal and vertical directions of manufacturing by LPBF. The hardness increased from 333~341 HV10 to 640~656 HV10 after heat treatment. Simultaneously, the ultimate tensile strength ( Rm ) increases from 1056~1096 Pa to 1964~2102 Pa, while the break elongation ( ε tot ) is reduced from 11.3~16.0% to 2.0~4.5%. Aged samples show a significant decrease in toughness in the Notch Impact Test. A specifically designed ball joint test setup has shown that the frame manufactured by LPBF provides comparable results as a conventionally manufactured frame and is robust and suitable for the prototype production and test of car headlamps.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2019 The Authors. Published by Elsevier B.V. eer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

Keywords: Maraging steel, LPBF, Mechanical properties Keywords: Maraging steel, LPBF, Mechanical properties

1. Introduction The laser powder bed fusion (LPBF) process – as a part of additive manufacturing (AM) – belongs to the powder bed fusion technology. The advantages of AM processes are i.a. geometrical freedom, material flexibility, creating opportunities to fabricate innovative parts with enhanced functionality Rüßmann, M. et al. (2015). MAR 300 is a well-known maraging steel, which belongs to a special class of ultra-high strength steels. Contrary to conventional steels, they are almost free of carbon and hardened by intermetallic precipitations. The quality of the final products is further influenced by powder feedstock used including the powder morphology, particle size distribution and shape. This morphology depends very strong on the state of the powder particles, as spray differs from screens, from used (sieved process powder) and so on. By processing (e.g., screening) the unused powder of the 1. Introduction The laser powder bed fusion (LPBF) process – as a part of additive manufacturing (A ) – belongs to the powder bed fusion technology. The advantages of A processes are i.a. geometrical freedom, material flexibility, creating opportunities to fabricate innovative parts with enhanced functionality Rüßmann, . et al. (2015). AR 300 is a well-known maraging steel, which belongs to a special class of ultra-high strength steels. Contrary to conventional steels, they are almost free of carbon and hardened by intermetallic precipitations. The quality of the final products is further influenced by powder feedstock used including the powder morphology, particle size distribution and shape. This morphology depends very strong on the state of the powder particles, as spray differs from screens, from used (sieved process powder) and so on. By processing (e.g., screening) the unused powder of the

* Corresponding author. E-mail address: t.simson@oth-aw.de (T. Simson). * Corresponding author. E-mail address: t.simson@oth-aw.de (T. Simson).

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.112 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.