The influence of pulsed laser powder bed fusion process parameters on Inconel 718 material properties

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:769

Article

Georgilas, Konstantinos^1,2  Khan, Raja H. U.³  Kartal, Mehmet E.¹ 

[1] Univ Aberdeen, Sch Engn, Aberdeen AB24 3UE, Scotland

[2] Natl Struct Integr Res Ctr, Cambridge CB21 6AL, England

[3] TWI Ltd, Cambridge CB21 6AL, England

关键词: Powder methods;    Nickel alloys;    Grains and interfaces;    Stress/strain measurements;    Characterisation;   

DOI  :  10.1016/j.msea.2019.138527

来源: Elsevier

【 摘 要 】

In this work, the effect of pulsed laser used during the powder bed fusion (L-PBF) additive manufacturing (AM) process on Inconel 718 (IN718) material properties has been investigated. Argon gas atomised (AGA) IN718 powder is characterised in terms of flow, density, particle size distribution and morphology. Powder shows mostly spherical morphology with Hausner ratio of 1.17 indicating good flow characteristics. Density optimisation trials are carried out by varying laser power and exposure time. Fabricated samples are characterised in terms of porosity by area fraction analysis using light microscopy and volume fraction analysis using X-ray microcomputed tomography (micro-CT). Minimum porosity of 0.16% is achieved for laser power of 200 W and exposure time of 110 mu s. Microstructural analysis using the Electron Backscatter Diffraction (EBSD) technique shows limited columnar grain structure in the 2 direction and more equiaxed type grains in the XY direction (normal to the Z direction). Tensile test results show 754 MPa yield strength, 1070 MPa ultimate tensile strength and similar to 24% elongation. Finally, hole drilling residual stress measurements show increase from similar to 0 MPa to over 450 MPa in tensile stress up to a depth of 1 mm from the top surface of the as-build L-PBF IN718 sample. It has been found that laser pulsing produces higher homogeneity in grain structure and better mechanical properties than that by the continuous laser method.

【 授权许可】

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