Lehmhus Dirk, Rahn Thomas, Struss Adrian, Gromzig Phillip, Wischeropp Tim, Becker Holger
Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, Wiener Straße 12, 28357 Bremen, Germany.
Fraunhofer Institute for Additive Production Technologies IAPT, Am Schleusengraben 14, 21029 Hamburg, Germany.
Materials (Basel). 2022 Oct 21;15(20):7386. doi: 10.3390/ma15207386.
The present study is dedicated to the evaluation of the mechanical properties of an additively manufactured (AM) aluminum alloy and their dependence on temperature and build orientation. Tensile test samples were produced from a standard AlSi10Mg alloy by means of the Laser Powder Bed Fusion (LPBF) or Laser Beam Melting (LBM) process at polar angles of 0°, 45° and 90°. Prior to testing, samples were stress-relieved on the build platform for 2 h at 350 °C. Tensile tests were performed at four temperature levels (room temperature (RT), 125, 250 and 450 °C). Results are compared to previously published data on AM materials with and without comparable heat treatment. To foster a deeper understanding of the obtained results, fracture surfaces were analyzed, and metallographic sections were prepared for microstructural evaluation and for additional hardness measurements. The study confirms the expected significant reduction of strength at elevated temperatures and specifically above 250 °C: Ultimate tensile strength (UTS) was found to be 280.2 MPa at RT, 162.8 MPa at 250 °C and 34.4 MPa at 450 °C for a polar angle of 0°. In parallel, elongation at failure increased from 6.4% via 15.6% to 26.5%. The influence of building orientation is clearly dominated by the temperature effect, with UTS values at RT for polar angles of 0° (vertical), 45° and 90° (horizontal) reaching 280.2, 272.0 and 265.9 MPa, respectively, which corresponds to a 5.1% deviation. The comparatively low room temperature strength of roughly 280 MPa is associated with stress relieving and agrees well with data from the literature. However, the complete breakdown of the cellular microstructure reported in other studies for treatments at similar or slightly lower temperatures is not fully confirmed by the metallographic investigations. The data provide a basis for the prediction of AM component response under the thermal and mechanical loads associated with high-pressure die casting (HPDC) and thus facilitate optimizing HPDC-based compound casting processes involving AM inserts.
本研究致力于评估增材制造（AM）铝合金的力学性能及其对温度和构建方向的依赖性。通过激光粉末床熔融（LPBF）或激光束熔化（LBM）工艺，以0°、45°和90°的极角从标准AlSi10Mg合金制备拉伸试验样品。在测试之前，样品在构建平台上于350°C应力消除2小时。在四个温度水平（室温（RT）、125、250和450°C）下进行拉伸试验。将结果与先前发表的关于经过和未经类似热处理的增材制造材料的数据进行比较。为了更深入地理解所得结果，分析了断口表面，并制备了金相切片用于微观结构评估和额外的硬度测量。该研究证实了在高温下，特别是在250°C以上，强度会显著降低：对于0°极角，室温下的极限抗拉强度（UTS）为280.2MPa，250°C时为162.8MPa，450°C时为34.4MPa。同时，断裂伸长率从6.4%分别增加到15.6%和26.5%。构建方向的影响显然受温度效应主导，室温下0°（垂直）、45°和90°（水平）极角的UTS值分别达到280.2、272.0和265.9MPa，偏差为5.1%。约280MPa的相对较低室温强度与应力消除有关，与文献数据吻合良好。然而，金相研究并未完全证实其他研究中报道的在相似或略低温度处理下胞状微观结构的完全破坏。这些数据为预测与高压压铸（HPDC）相关的热和机械载荷下增材制造部件的响应提供了基础，从而有助于优化涉及增材制造嵌件的基于HPDC的复合铸造工艺。
