Defect analysis and fatigue design basis for Ni-based superalloy 718 manufactured by selective laser melting
| Autor: | Yoichi Yamashita, Yukitaka Murakami, Rei Mihara, Takao Murakami, Masami Okada |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Fusion
Gas porosity Materials science Mechanical Engineering Fracture mechanics 02 engineering and technology 021001 nanoscience & nanotechnology Fatigue limit Industrial and Manufacturing Engineering Superalloy 020303 mechanical engineering & transports 0203 mechanical engineering Machining Mechanics of Materials Modeling and Simulation Vickers hardness test General Materials Science Selective laser melting Composite material 0210 nano-technology |
| Zdroj: | International Journal of Fatigue. 117:485-495 |
| ISSN: | 0142-1123 |
| Popis: | It is well known that high strength metallic materials with Vickers hardness HV > 400 are very sensitive to small defects. This paper discusses fatigue properties of a Ni-based Superalloy 718 with HV = ∼470 manufactured by additive manufacturing (AM). The advantage of AM has been emphasized as the potential application to high strength or hard steels which are difficult to manufacture by traditional machining to complex shapes. However, the disadvantage or challenge of AM has been pointed out due to defects which are inevitably contained in the manufacturing process. Defects of the material investigated in this study were mostly gas porosity and those made by lack of fusion. The successful application of the area parameter model was confirmed. Although the statistics of extremes analysis is useful for the quality control of AM, the particular surface effect on the effective value of defect size must be carefully considered. Since the orientations of defects in AM materials are random, a defect in contact with specimen surface has higher influence on fatigue strength than an internal defect and has the effective larger size termed as area eff than the real size, area , of the defect from the viewpoint of fracture mechanics. The guide for the fatigue design and development of higher quality Ni-based Superalloy 718 by AM processing based on the combination of the statistics of extremes on defects and the area parameter model is proposed. |
| Databáze: | OpenAIRE |
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