Microstructure and hydrogen embrittlement of additively manufactured Ti-6Al-4V

Magnus Neikter, 1988- (Författare), Marta-Lena Antti (Handledare), Pia Åkerfeldt (Handledare), Robert Pederson (Handledare), Ola Harrysson (Opponent)

ISBN 9789177903970, URI http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-73905, URN urn:nbn:se:ltu:diva-73905

Luleå tekniska universitet Institutionen för teknikvetenskap och matematik (Utgivare)

utgivning

Luleå : Luleå University of Technology, 2019

Seriemedlemskap

Doctoral thesis / Luleå University of Technology 1 jan 1997 → … · ISSN 1402-1544, ISSN 1402-1544 · Doctoral thesis / Luleå University of Technology 1 jan 1997 → …

Onlineresurs

Digital resurs · 2 bibliotek

Finns online:

http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-73905

Värdpublikation

ämne

Natural Sciences, Chemical Sciences, Materials Chemistry, Naturvetenskap, Kemi, Materialkemi, Engineering and Technology, Materials Engineering, Other Materials Engineering, Teknik, Materialteknik, Annan materialteknik, Engineering Materials, Materialteknik, Ti-6Al-4V, Additive Manufacturing, Texture, Microstructure, Hydrogen Embrittlement

Annat bärarformat

ISBN 9789177903963 · ISBN 9789177903963 (Annat format)

Fler detaljer Referera

Sammanfattning

The work of this doctoral thesis has been performed between the 24 th of August 2015 to the 6 th of September 2019. The general purpose of this work has been to increase the knowledge of additively manufactured Ti-6Al-4V when it comes to microstructure, texture and hydrogen embrittlement. Several additive manufacturing (AM) processes have been addressed, the main focus, however, has been on the two processes electron beam melting (EBM) and selective laser melting (SLM). The work has been performed at Luleå University of Technology and at Monash Centre of Additive Manufacturing (MCAM), which is a part of Monash University, Melbourne Australia. GKN Aerospace Engine Systems has been involved in the work as a collaborative industrial partner. Where the main interaction and support has been between GKN in Trollhättan, Sweden. GKNs facility in Filton, United Kingdom, however, has also been involved in sample production. The texture measurements using neutron time of flight (TOF) diffraction were performed in Dubna, Russia at Frank Laboratory of Neutron Physics at the Joint Institute for Nuclear Research, using the spektrometer kolitshestvennovo analiza tekstury (SKAT) instrument and in Los Alamos at Los Alamos Neutron Science Center, using the texture instrument high pressure preferred orientation (HIPPO). The interest of specifically additively manufactured Ti-6Al-4V originates from GKN Aerospace Engine Systems as they have been contracted to manufacture parts for the Ariane rockets. In aerospace, weight is of utter importance as reduced weight of the components reduce the fuel costs and makes it possible to transport increased loads. Therefore, titanium has been suggested to replace heavier metal alloys (such as nickel-based superalloys) due to titanium’s high specific strength and overall good properties. The work has been managed under the supervision of Professor Marta-Lena Antti, Professor Robert Pederson and Dr. Pia Åkerfeldt at Luleå University of Technology and by Professor Xinhua Wu and Professor Aijun Huang at MCAM. The project has been financed by three parties Space for Innovation and Growth (RIT), Nationellt Rymdtekniskt Forskningsprogram (NRFP) and the Graduate School of Space Technology . The thesis is composed of a literature review along with the appended papers that have been written throughout the duration of the project. The purpose of the literature review is to give the reader a broader knowledge and context about the theory behind the work conducted during the Ph.D. project. The thesis commences with a theoretical background about titanium, its crystal structures, microstructure, and AM. The chapter about AM is divided into three sub-chapters, explaining the two different AM sub-groups directed energy deposition (DED) and powder bed fusion (PBF). Then the chapter finalizes with explaining the benefits and drawbacks with AM. Once these subjects been explained there is a chapter explaining AM built Ti-6Al-4V. The theme of this chapter is the differences in the microstructure of AM built and conventional built Ti-6Al-4V, where phenomena like chessboard pattern and layers bands are discussed, followed by a comparative section of the mechanical properties. The chapter about AM built Ti-6Al-4V is followed by a chapter about texture where the two texture techniques electron backscattered diffraction (EBSD) and neutron (TOF) diffraction are explained. The literature review then continues with the chapters neutron tomography, hydrogen embrittlement, and fatigue crack growth. Then there is a chapter about the materials and experimental methods that have been used to perform all the experiments, then a summary of all the papers and conclusions. After the conclusions, the thesis finalizes with a chapter about possible future work and an outlook into the future of AM. In the end, the papers I to IV are appended.