Processing and characterization of crack-free aluminum 6061 using high-temperature heating in laser powder bed fusion additive manufacturing
By S. Uddin, L. Murr, C. Terrazas, P. Morton, D. Roberson, Ryan B. Wicker. Additive Manufacturing, 2018
264 citations recorded by the source corpus.
Abstract During solidification of many so-called high-performance engineering alloys, such as 6000 and 7000 series aluminum alloys, which are also unweldable autogenously, volumetric solidification shrinkage and thermal contraction produces voids and cracks. During additive manufacturing processing, these defects can span the length of columnar grains, as well as intergranular regions. In this research, laser powder bed fusion (LPBF) of aluminum alloy (AA) 6061 used powder bed heating at 500 °C in combination with other experimentally determined processing parameters to produce crack-free components. In addition, melt-pool banding, which is a normal solidification feature in LPBF, was eliminated, illustrating solidification process modification as a consequence of powder bed heating. Corresponding microindentation hardness and tensile testing of the as-fabricated AA6061 components indicated an average Vickers hardness of HV 54, and tensile yield, ultimate strength, and elongation values of 60 MPa, 130 MPa, and 15%, respectively. These mechanical properties and those of heat treated parts showed values comparable to annealed and T6 heat treated wrought products, respectively. X-ray diffraction and optical microscopy revealed columnar grain growth in the build direction with the as-fabricated, powder-bed heated product microstructure characterized by [100] textured, elongated grains (∼ 25 μm wide by 400 μm in length), and both intragranular and intergranular, noncoherent Al-Si-O precipitates which did not contribute significantly to the mechanical properties. The results of this study are indicative that powder bed heating may be used to assist with successful fabrication of AA6061 and other alloy systems susceptible to additive manufacturing solidification cracking.
Subfields: Automotive Engineering, Mechanical Engineering
View Paper: https://www.semanticscholar.org/paper/b52b0a34096191f1b09ecde1fc4ddee4e67e9db4
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Citations in the corpus
- A review of Laser Powder Bed Fusion Additive Manufacturing of aluminium alloys: Microstructure and properties (2021, background): “Another approach that researchers have explored is heating the base plate up to 500 °C, which reduces residual stress during the build and supresses hot cracking [82].”
- Towards high-temperature applications of aluminium alloys enabled by additive manufacturing (2021, background): “tion of solutes that reduce the freezing range of the alloys, such as Si [3–5], substrate/powder bed preheating [6], mixing of elemental powders [7], or promot-”
- Additive manufacturing for energy: A review (2020, background): “Aluminum 6061 Crack-free Nuclear energy, Oil & gas [49]”