Fatigue Assessment of Wire and Arc Additively Manufactured Ti-6Al-4V

Sebastian Springer*, Martin Leitner, Thomas Gruber, Bernd Oberwinkler, Michael Lasnik, Florian Grün

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Wire and arc additively manufactured (WAAM) parts and structures often present internal defects, such as gas pores, and cause irregularities in the manufacturing process. In order to describe and assess the effect of internal defects in fatigue design, this research study investigates the fatigue strength of wire arc additive manufactured structures covering the influence of imperfections, particularly gas pores. Single pass WAAM structures are manufactured using titanium alloy Ti-6Al-4V and round fatigue, tensile specimen are extracted. Tensile tests and uniaxial fatigue tests with a load stress ratio of R = 0.1 were carried out, whereby fatigue test results are used for further assessments. An extensive fractographic and metallographic fracture surface analysis is utilized to characterize and measure crack-initiating defects. As surface pores as well as bulk pores are detected, a stress intensity equivalent ∆Keqv transformation approach is presented in this study. Thereby, the defect size of the surface pore is transformed to an increased defect size, which is equivalent to a bulk pore. Subsequently, the fatigue strength assessment method by Tiryakioğlu, commonly used for casting processes, is applied. For this method, a cumulative Gumbel extreme value distribution is utilized to statistically describe the defect size. The fitted distribution with modified data reveals a better agreement with the experimental data than unmodified. Additionally, the validation of the model shows that the usage of the ∆K modified data demonstrates better results, with a slight underestimation of up to about −7%, compared to unmodified data, with an overestimation of up to about 14%, comparing the number of load cycles until failure. Hence, the presented approach applying a stress intensity equivalent transformation of surface to bulk pores facilitates a sound fatigue strength assessment of WAAM Ti-6Al-4V structures.

Original languageEnglish
Article number795
Issue number5
Publication statusPublished - May 2022


  • defects
  • fatigue assessment
  • statistical distribution
  • Ti-6Al-4V
  • wire arc additive manufacturing

ASJC Scopus subject areas

  • Materials Science(all)
  • Metals and Alloys


Dive into the research topics of 'Fatigue Assessment of Wire and Arc Additively Manufactured Ti-6Al-4V'. Together they form a unique fingerprint.

Cite this