13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- Tensile testing was conducted on solid material manufactured by selective laser melting and material produced by hot-rolling. Figure 7 shows typical tensile stress-strain data. The SLM material was tested in the as-manufactured state, whilst the hot-rolled material is tested in a solution heat treated material condition. In Figure 8 and Figure 9 more detailed tensile test results are shown for ambient and elevated temperature testing. Data are normalized to average values for hot-rolled Hastelloy X material. mechanical strain ε mechanical stress σ 0° 90° HX Figure 7. Generalized results from tensile testing of solid bars, stress-strain curves for standard Hastelloy X (HX), SLM Alloy X (0° and 90°). 0 0,5 1 1,5 2 2,5 3 0 200 400 600 800 1000 temperature [°C] normalized yield stress, Rp0.2 norm [-] α = 0° α = 45° α = 90° Figure 8. Normalized yield stress. Dashed line Rp0.2 =1 equals hot-rolled material. 0 0,2 0,4 0,6 0,8 1 1,2 1,4 0 200 400 600 800 1000 temperature [°C] normalized ultim. tensile stress, Rm norm [-] α = 0° α = 45° α = 90° Figure 9. Normalized ultimate tensile stress. Dashed line Rm =1 equals hot-rolled material. Due to the weld-like manufacturing process, the material is highly anisotropic. This is clearly shown above in material data (Figure 7 to Figure 9) together with microstructural observations in Figure 4. 3.2. Lattice truss structures Tensile testing has been performed on geometries as shown above, Figure 5. Results are presented and discussed below. From tensile tests, data for hollow, open lattice and hybrid structures are presented in Figure 10. The data set is a typical response from testing and represents all geometry variations 2.2 – 3.0 included in the test series. The component stiffness can be calculated as the slope of the force-displacement curve for hollow,
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