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Effects of Internal Defects and Residual Stress on Fatigue Properties of a Titanium Alloy (Ti- 6Al-4V) Fabricated Via Electron Beam Melting (EBM)

Published

Author(s)

Nikolas W. Hrabe, Timothy P. Quinn, Thomas H. Gnaeupel-Herold

Abstract

A clear understanding of the fatigue properties of Ti-6Al-4V manufactured with electron beam melting (EBM) is needed to ensure performance in critical applications in the medical device and aerospace industries. In this work, the effects of residual stress and internal defects (pores and voids) on fatigue properties of EBM Ti-6Al-4V material in as-built, stress-relieved, and hot isostatic pressed (HIPed) conditions were evaluated. Conventional techniques were used to measure the chemical composition and quantify microstructures, and neutron scattering was utilized to measure residual stresses. Post-processing did not alter chemical composition. Compared to the as-built condition, microstructure was unchanged for stress-relieved material and coarser for HIPed material. No significant residual stresses were measured for any of the three conditions. This indicates build platform and layer preheating lead to sufficient process temperatures to achieve full stress relief in-situ. The fatigue strengths at 107 cycles measured for the as-built and stress-relieved conditions were statistically similar and were measured to be 200 MPa to 250 MPa. A significantly higher fatigue strength at 107 cycles of 550 MPa to 600 MPa was measured for the HIPed condition. The increase in fatigue endurance limit was attributed to a reduction in internal porosity and void content.
Conference Dates
November 7-10, 2016
Conference Location
Tsukuba
Conference Title
World Materials Research Institutes Forum International Workshop for Young Scientists

Citation

Hrabe, N. , Quinn, T. and , T. (2016), Effects of Internal Defects and Residual Stress on Fatigue Properties of a Titanium Alloy (Ti- 6Al-4V) Fabricated Via Electron Beam Melting (EBM), World Materials Research Institutes Forum International Workshop for Young Scientists, Tsukuba, -1, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=921698 (Accessed April 19, 2024)
Created November 1, 2016, Updated February 21, 2017