MSE 2016 - Full Program

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Process-Induced Material Characteristics and its Effect on Fatigue Reliability of Selective Laser Melted Al- and Ti-Alloys

Tuesday (27.09.2016)
15:45 - 16:00
Part of:

Due to additive manufacturing and its special process conditions (small melt pool, high cooling rates) new material characteristics evolve compared to conventional manufacturing, like forming or cutting. This study investigates the fatigue properties of AlSi12 and Ti6Al4V structures processed by selective laser melting (SLM). Different processing parameters of the SLM process together with post heat-treatment and mechanical-processing have been investigated to achieve parameters for optimized fatigue performance. Differences in fatigue properties have been correlated to the microstructural and surface modifications. For AlSi12, the influence of laser energy density, base plate heating and the post-build heat treatment as well as stress relief was investigated. Due to change in porosity and dendritic width, the parameter settings show a significant influence on the high cycle (HCF) as well as on very high cycle fatigue (VHCF) properties until 10^9 – 10^10 cycles. The fatigue life scatter could be reduced from 52 % to 15 % and VHCF strength increased by 47 % using optimized parameter settings. For Ti6Al4V, the influence of surface-processing (polishing, shot-peening) and hot isostatic pressing (HIP) were investigated. As polishing and shot-peening has a significant influence on the roughness, surface hardness and residual stresses, the HCF strength could be improved due to polishing (+125 %) and shot-peening (+107 %). By reducing the porosity with HIP treatment, the HCF and VHCF strength of polished specimen could be further increased by more than 30 % (HCF) and 116 % (VHCF). The results prove that fatigue reliability can be reached by optimized SLM process parameters and adapted post-processing strategies.

M.Sc. Jochen Tenkamp
TU Dortmund University
Additional Authors:
  • Shafaqat Siddique
    TU Dortmund University
  • Muhammad Imran
    TU Dortmund University
  • Prof. Dr. Frank Walther
    TU Dortmund University
  • Eric Wycisk
    Laser Zentrum Nord (LZN)
  • Prof. Dr. Claus Emmelmann
    Laser Zentrum Nord (LZN)