PSI - Issue 42

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ScienceDirect

Procedia Structural Integrity 42 (2022) 529–536 Structural Integrity Procedia 00 (2019) 000–000 Structural Integrity Procedia 00 (2019) 000–000

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

© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 Abstract Additive Manufacturing has been developed to fulfill the current growing demand for design freedom structures with near-net complex shapes. The additive manufacturing process is associated with lots of defects such as porosities, incomplete fusion, hot cracking, delamination, etc. These defects act as stress raiser and are known to deteriorate the mechanical properties of the alloy. In this present study, the defect-based fatigue performance of selective laser melted Ti6Al4V alloy has been investigated. The Ti6Al4V alloy specimens were vertically built with optimized process parameters and layer thickness of 60 µ m. These as-built specimens were subjected to heat treatment in order to reduce the residual stress generated due to higher thermal gradient. The as-built alloy mainly consisting of α ’ martensitic microstructure decomposes into α - β microstructure with the heat treatment. The mechanical properties and fatigue performance were then evaluated. Most of the fatigue failure occurred from the surface and sub-surface regions. The endurance limit then predicted using the defects’-based model using the defects’ area and its location. 2020 The Authors. Published by Elsevier B.V. is is an open access article under the CC BY-NC-ND license (http: // creativec mmons.org / licenses / by-nc-nd / 4.0 / ) r-review under responsibility of 23 European Conference on F acture – ECF23 . Keywords: Additive Manufacturing; Titanium; Fatigue; Defects. Additive manufacturing (AM) is the recent manufacturing technology to fabricate the near-net complex structure. Selective laser melting (SLM) technique is one of the types of additive manufacturing technologies (Yakout et al. (2018)). SLM provides design freedom and can be used to fabricate intricate structure which otherwise next to im possible with conventional manufacturing techniques (Yap et al. (2015)). Ti6Al4V alloy is one of the candidate alloys that can be easily additively manufactured and finds a wide range of applications in aerospace, biomedical, automotive and chemical industries owing to their high specific strength, good corrosion resistant, biocompatibility, etc (Veiga et al. (2012)). However, it is inherent to poor thermal conductivity, which results in poor machinability (Pimenov et al. (2021)). Processing of Ti6Al4V alloy with the conventional manufacturing techniques requires higher energy input and often leads to significant material wastage. Hence, fabrication of Ti6Al4V alloy with additive manufacturing has gained much popularity in the recent years. Despite several advantages, the components fabricated by SLM are asso ciated with high residual stresses (Acevedo et al. (2020)) and lots of process-induced defects (Mostafaei et al. (2022)). 23 European Conference on Fracture – ECF23 A study on defect-induced fatigue failures in SL Ti6Al4V Alloy Litton Bhandari a , Vidit Gaur a, ∗ a Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Uttarakhand – 247 667, India Abstract Additive Manufacturing has been developed to fulfill the current growing demand for design freedom structures with near-net complex shapes. The additive manufacturing process is associated with lots of defects such as porosities, incomplete fusion, hot cracking, delamination, etc. These defects act as stress raiser and are known to deteriorate the mechanical properties of the alloy. In this present study, the defect-based fatigue performance of selective laser melted Ti6Al4V alloy has been investigated. The Ti6Al4V alloy specimens were vertically built with optimized process parameters and layer thickness of 60 µ m. These as-built specimens were subjected to heat treatment in order to reduce the residual stress generated due to higher thermal gradient. The as-built alloy mainly consisting of α ’ martensitic microstructure decomposes into α - β microstructure with the heat treatment. The mechanical properties and fatigue performance were then evaluated. Most of the fatigue failure occurred from the surface and sub-surface regions. The endurance limit then predicted using the defects’-based model using the defects’ area and its location. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of 23 European Conference on Fracture – ECF23 . Keywords: Additive Manufacturing; Titanium; Fatigue; Defects. 1. Introduction Additive manufacturing (AM) is the recent manufacturing technology to fabricate the near-net complex structure. Selective laser melting (SLM) technique is one of the types of additive manufacturing technologies (Yakout et al. (2018)). SLM provides design freedom and can be used to fabricate intricate structure which otherwise next to im possible with conventional manufacturing techniques (Yap et al. (2015)). Ti6Al4V alloy is one of the candidate alloys that can be easily additively manufactured and finds a wide range of applications in aerospace, biomedical, automotive and chemical industries owing to their high specific strength, good corrosion resistant, biocompatibility, etc (Veiga et al. (2012)). However, it is inherent to poor thermal conductivity, which results in poor machinability (Pimenov et al. (2021)). Processing of Ti6Al4V alloy with the conventional manufacturing techniques requires higher energy input and often leads to significant material wastage. Hence, fabrication of Ti6Al4V alloy with additive manufacturing has gained much popularity in the recent years. Despite several advantages, the components fabricated by SLM are asso ciated with high residual stresses (Acevedo et al. (2020)) and lots of process-induced defects (Mostafaei et al. (2022)). 23 European Conference on Fracture – ECF23 A study on defect-induced fatigue failures in SLM Ti6Al4V Alloy Litton Bhandari a , Vidit Gaur a, ∗ a Department of Mechanical and Industrial Engineering, Indian Institute of Technology Roorkee, Uttarakhand – 247 667, India 1. Introduction

∗ Corresponding author. Tel.: + 91-1332-284909 ; fax: + 0-000-000-0000. E-mail address: vidit.gaur@me.iitr.ac.in ∗ Corresponding author. Tel.: + 91-1332-284909 ; fax: + 0-000-000-0000. E-mail address: vidit.gaur@me.iitr.ac.in

2452-3216 © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the 23 European Conference on Fracture – ECF23 10.1016/j.prostr.2022.12.067 2210-7843 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review u der responsibility of 23 European Conference on Fracture – ECF23 . 2210-7843 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of 23 European Conference on Fracture – ECF23 .