Abstract
Four innovative hybrid scanning strategies (0° + 67°, 45° + 67°, 67° + 67° and 90° + 67°) of laser powder bed fusion (LPBF) have been proposed to tailor the microstructure and mechanical properties of Inconel 625 alloy for the first time. The experiment results revealed in sample I (0° + 67°) and sample IV (90° + 67°) a gradient structure is formed, progressing from randomly textured slender columnar crystals (001) to randomly textured equiaxial fine crystals, and finally to equiaxial and fine columnar crystals. In samples II (45° + 67°) and III (67° + 67°), isometric and columnar crystals are uniformly distributed throughout the sample. The tensile strengths of samples treated via hybrid scanning strategy in LPBF (sample I: 1270 ± 8 MPa, sample II: 1400 ± 6 MPa, sample III: 1390 ± 5 MPa and sample IV: 1360 ± 5 MPa) surpassed those of conventionally manufactured samples, including Inconel 625 alloy fabricated by LPBF using a single scanning strategy. This superiority can be attributed to the presence of fine grains, elevated residual stress levels, and the formation of stacking faults. The results of the nanoscratch test reveal that the bottom surface of samples I and IV demonstrates superior abrasion resistance in comparison to the top surface, which can be attributed to the higher relative density, finer grain size, lower elastic modulus and lower Schmidt factors in the bottom surface. These findings hold significant implications for tailoring the microstructure and properties of Inconel 625 alloy, especially in the realm of additively manufactured materials featuring heterogeneous structures.
Published Version
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