13th International Conference on Fracture June 16–21, 2013, Beijing, China -6- easily detected, therefore an EBSD analysis has been performed. An example of the results is shown below, Figure 5. It is obvious that the structure is columnar and that the microstructure has a coupling to solidification. In the process, the build plate is kept at a constant temperature and the solidified material is surrounded by loosely packed metal powder, i.e. the metal powder will act as insulation for heat from the weld process. The columnar structure is an indication on conditions for heat transfer. Since the columnar structure is vertical in the image, the cooling gradient is mainly normal to the build platform. 20µm Figure 5. EBSD image of as-manufactured Alloy X. Build direction is indicated by an arrow in the figure. 3.2 Fatigue testing Testing of the material at low temperature has been conducted as low cycle fatigue testing in strain control with a triangular wave shape and a strain ratio Rε=1. Results are shown below, Figure 6. 0 0,2 0,4 0,6 0,8 1 1,2 1,4 hot-rolled SLM 90° SLM 45° SLM 0° cast material strain range at Nf norm=1, Δε tot [%] Figure 6. Normalized low cycle fatigue test results at ambient temperature. Fracture surfaces of fatigue tested material have been evaluated by light optical microscopy and scanning electron microscopy. Corresponding typical micrographs are shown below, Figure 7 and
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