Tensile and high cycle fatigue properties of annealed TI6AL4V (ELI) specimens produced by direct metal laser sintering

CITATION: Malefane, L. B., et al. 2018. Tensile and high cycle fatigue properties of annealed TI6AL4V (ELI) specimens produced by direct metal laser sintering. South African Journal of Industrial Engineering, 29(3):299-311, doi:10.7166/29-3-2077.The original publication is available at http://sajie.journals.ac.zaENGLISH ABSTRACT: The tensile and high cycle fatigue (HCF) properties of high temperature annealed (HTA) direct metal laser sintered (DMLS) Ti6Al4V extra low interstitial (ELI) machined and polished specimens were investigated. The HTA heat treatment of the specimens resulted in the nucleation and growth of the alpha and beta grains from the acicular martensite grains, improving their elongation to failure. The specimens were micro-CT scanned in an attempt to relate the pores in the specimens to their fatigue properties. The micro-CT pore information from suspected crack initiation pores on the surfaces of eventual fracture was used to calculate the stress intensity factors, which correlated well with the decreasing cycles to failure of the fatigue test specimens for all three build directions. Three representative specimens were analysed, and the ‘killer pore’ was identified in each micro-CT scan and fractograph, all of which were proximal to the surface of the specimen.AFRIKAANSE OPSOMMING: Die trek- en hoë-siklus vermoeidheidseienskappe van hoë temperatuur uitgegloeide direkte metaal lasergesinterde Ti6AL4V ekstra lae interstisiële gemasjineerde en poleerde monsters is ondersoek. Die spesifieke hitte behandeling van die monsters het gelei tot kernvorming en groei van alfa en beta korrels van die naaldvormige ′ martensiet korrels; dit het hul verlenging voor faling verbeter. Die monsters is op ʼn mikroskaal skandeer in ʼn poging om ʼn verband te vind tussen die porieë in die monsters en hul vermoeidheidseienskappe. Die porie inligting van vermoede kraakinisiëring porieë op die oppervlakke en gevolglike verbreking is gebruik om die spanningintensiteit te bereken. Dit het korreleer met die verminderde siklusse tot faling van die monsters vir al drie bou rigtings. Drie verteenwoordige monsters is analiseer en die porie waar die kraking begin het, is in elke geval identifiseer. Al hierdie gevalle was proksimaal tot die oppervlak van die monsterhttp://sajie.journals.ac.za/pub/article/view/2077Publisher's versio