Recently, the research team of the University of Science and Technology of China reported its latest achievements in aluminum alloy 3D printing technology. After the T6 heat treatment of aluminum alloy samples prepared by the SLM process, researchers found that the ductility of aluminum alloy has been significantly improved.
AlSi10Mg aluminum alloy samples are prepared by SLM process, followed by T6 heat treatment, which mainly includes solution treatment at 535oC and artificial aging treatment at 158oC (10 hours), and then the mechanical properties of the aluminum alloy samples are tested And microstructure observation and analysis. Figure 1 shows the process of preparing aluminum alloy samples by SLM process.
Compared with steel or titanium alloys, aluminum alloys face three challenges in the preparation of SLM: (a) the high reflectivity of aluminum powder to the laser beam, (b) high heat conduction, and (c) the aluminum element is relatively active and extremely It is easy to form an oxide film on the surface. For example, the thermal conductivity of the AlSi10Mg casting used in this study reached 113 W/m K. The main trouble caused by the high thermal conductivity is that the metal transforms from liquid to solid and cools very quickly, resulting in the solidified metal. The high residual stress causes internal cracks in the castings and seriously affects its service performance.
Therefore, people have conducted a lot of research on how to improve the elongation, hardness, tensile strength and fatigue strength of SLM process aluminum alloy. And it is found that AlSi10Mg alloy prepared by SLM obviously exceeds other alloys in strength and hardness, but its ductility is relatively poor. And finally through the aforementioned T6 heat treatment, the ductility of the AL alloy can be significantly improved, thereby providing process guidance for the practical application of this type of aluminum alloy.
The test results show that the density of the aluminum alloy samples before and after heat treatment does not change much, the tensile strength and bending strength are slightly reduced, the reduction is 19.97% (from 334 MPa to 267.3 MPa) and 6.1%, respectively, and the hardness is reduced by about 20 %. However, the ductility of aluminum alloy has been significantly improved, with elongation increased by 155% (from 3.64% to 9.28%) and fracture deflection increased by 122.9%, showing the better comprehensive mechanical properties of aluminum alloy.
This will make 3D printed aluminum alloy parts have a wider range of application value. Figure 2 shows the micro morphology of the tensile section and the curved section of the test sample. This achievement enables 3D printing technology to provide more application opportunities in the preparation of aluminum alloys.
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