PSI - Issue 17

Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 17 (2019) 222–229

ICSI 2019 The 3rd International Conference on Structural Integrity Propagation of long fatigue cracks in Ti6Al4V alloy produced by direct metal laser sintering Ludvík Kunz 1 *, Pavel Pokorný 1 , Radomila Konečná 2 , Gianni Nicoletto 3 1 Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, Brno 61662, Czech Republic, 2 University of Žilina, Univerzitná 1, Žilina 01026, Slovakia, 3 University of Parma, Parco Area delle Scienze181/A Parma 43100, Italy. ICSI 2019 The 3rd International Conference on Structural Integrity Propagation of long fatigue crack in Ti6Al4V alloy produced by direct metal laser sintering Ludvík Kunz 1 *, Pavel Pokorný 1 , Radomila Konečná 2 , Gianni Nicoletto 3 1 Institute of Physics of Materials, Acade y of Sciences of the Czech Republic, Žižkova 22, Brno 61662, Czech Republic, 2 University of Žilina, Univerzitná 1, Žilina 01026, Slovakia, 3 University of Parma, Parco Area delle Scienze181/A Parma 43100, Italy. The growth of long fatigue cracks in Ti6Al4V alloy manufactured by direct metal laser sintering was experimentally determined on CT specimens. The crack propagation was investigated in three different orientations with regard to the building direction. The as-built CT specimens were heat treated at temperatures 380, 740 and 900 °C. The crack growth curves with the threshold values of the stress intensity factor  K th were determined. The measurement was carried out in laboratory air at room temperature and stress ratios R = 0.1 and 0.8. It was found that the crack growth rate in the Paris region is identical for all three heat treatments for the same R ratio. For the particular stress intensity factor range  K the crack growth rates at R = 0.1 and 0.8 differs by factor of two. Contrary to the Paris region there is a clear effect of the heat treatment in the near threshold region. For the material heat treated at 380 °C and loaded at R = 0.1 the threshold is 3.7 MPam 1/2 , for 740 °C 2.7 MPam 1/2 and for 900 °C 3.5 MPam 1/2 . The explanation of the observed dependence of the threshold on the post processing heat treatment is discussed in terms of microstructure and residual stresses. e growth of long fatigue cracks in Ti6Al4V alloy manufactured by direct metal laser sintering was experimentally determined on CT specimens. The crack pr pagation was investigated in three different orientations with regard to the building direction. The as-built CT specimens were heat treated at temperatures 380, 740 and 900 °C. The crack growth curves with the threshold values of the stress intensity factor  K th were determined. The measurement was carried out in laboratory air at room temperature and stress ratios R = 0.1 and 0.8. It was found that the crack growth rate in the Paris region is identical for all three eat treatments for the same R ratio. F r the particular stress intensity factor range  K the crack growth rates at R = 0.1 and 0.8 differs by factor of two. Contrary to the Paris region there is a clear effect f the heat treatment in the near threshold region. For the material heat treated at 380 °C and loaded at R = 0.1 the threshold is 3.7 MPam 1/2 , for 740 °C 2.7 MPam 1/2 and for 900 °C 3.5 MPam 1/2 . The explanation of the observed dependence of the threshold on the post processing heat treatment is discussed in terms of microstructure and residual stresses. Abstract Abstract

© 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. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. P er-review under responsibility of the ICSI 2019 organiz r . Keywords: Long fatigue crack growth; Ti6Al4V; direct metal laser sintering

Keywords: Long fatigue crack growth; Ti6Al4V; direct metal laser sintering

* Corresponding author. Tel.: +420-604-873-893 E-mail address: kunz@ipm.cz

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. * Corresponding author. Tel.: +420-604-873-893 E-mail address: kunz@ipm.cz

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.030