title: Fatigue behavior of highly porous titanium produced by powder metallurgy with temporary space holders.
abstract: Porous titanium cylinders were produced with a constant amount of temporary space holder (70 vol.%). Different interstitial contents were achieved by varying the starting powders (HDH vs. gas atomized) and manufacturing method (cold compaction without organic binders vs. warm compaction of MIM feedstocks). Interstitial contents (O, C, and N) as a function of manufacturing were measured by chemical analysis. Samples contained 0.34-0.58 wt.% oxygen, which was found to have the greatest effect on mechanical properties. Quasi-static mechanical tests under compression at low strain rate were used for reference and to define parameters for cyclic compression tests. Not unexpectedly, increased oxygen content increased the yield strength of the porous titanium. Cyclic compression fatigue tests were conducted using sinusoidal loading in a servo-hydraulic testing machine. Increased oxygen content was concomitant with embrittlement of the titanium matrix, resulting in significant reduction of compression cycles before failure. For samples with 0.34 wt.% oxygen, R, σ(min) and σ(max) were varied systematically to estimate the fatigue limit (~4 million cycles). Microstructural changes induced by cyclic loading were then characterized by optical microscopy, SEM and EBSD.
authors.affiliation: Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK), 52425 Jülich, Germany; Gazi University, Faculty of Technology, Department of Metallurgical and Materials Engineering, Teknikokullar, Ankara, Turkey.
authors.forename: Sedat
authors.initials: S
authors.lastname: Özbilen
authors.affiliation: Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK), 52425 Jülich, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Liebert
authors.affiliation: Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK), 52425 Jülich, Germany; University of Kaiserslautern, Lehrstuhl für Werkstoffkunde (WKK), D-67663 Kaiserslautern, Germany.
authors.forename: Tilmann
authors.initials: T
authors.lastname: Beck
authors.affiliation: Forschungszentrum Jülich, Institute of Energy and Climate Research (IEK), 52425 Jülich, Germany. Electronic address: m.bram@fz-juelich.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Bram
mesh_terms: D019245:Compressive Strength; D008422:Materials Testing; D008669:Metallurgy / Q000379:methods; D016062:Porosity; D014025:Titanium / Q000737:chemistry*
chemical_list: D014025:Titanium
keywords: Failure mechanisms; Fatigue behavior; Fatigue limit; Interstitial content; Porous titanium; Powder metallurgy