13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- a finished geometry is formed. After finalization, the remaining loose powder is removed and the component is cut off from the build platform. 2. Experimental details Since no harmonized nomenclature exists in the literature for specimen build / loading direction relative to build platform or build direction, it is necessary to give a reference to nomenclature used in the current paper. If the build platform is taken as reference, a specimen being built in the build platform plane (perpendicular to the build direction) the specimen build and loading direction is designated 0°. Any specimen build and loading direction tilted towards the normal of the build platform plane (i.e. a vector defining the machine global build direction) would be designated with a build angle 0° < α ≤ 90°. Due to the nature of the SLM process, the layer-wise build-up of material is normally done with a scan strategy so that the material will be isotropic in the build plane. For each layer the scanning pattern is rotated and in a component the material will contain welds in many different directions. Any rotation of a specimen in the plane is considered to give corresponding results and the material can be considered as orthotropic [11]. The findings have been verified for 1.4404 [12]. The present definition of specimen build direction / loading direction is graphically visualized below, Figure 2. x y x y x y z α = 90° α = 45° α = 0° α α Figure 2. Definition of specimen build and loading direction relative to the build platform plane. A specimen “0°” would be a specimen in any direction in the build plane and a specimen “α°” (0° < α < 90°) would be a specimen built out of the build platform. An angle α = 90° would indicate a specimen being built parallel to the SLM equipment build direction. 2.1. Process Material manufacturing has been done in an Eosint M270 Dual Mode equipment. The atmosphere during building is Argon and the atmosphere is monitored by an oxygen probe throughout the entire process to ensure that the oxygen level is kept below a maximum level. A layer thickness of 20µm was used and for each new layer the laser beam rotated the scanning pattern and shifted the scanning pattern in order to avoid in-plane property variations. 2.2. Material11 For the material manufacturing, a nickel base superalloy in accordance to Hastelloy X (originally developed by Haynes International) has been used. The material is Ar gas atomized and sieved to a fraction suitable for selective laser melting applications, indicating a powder distribution from
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