High-Temperature Mechanical Properties of Stress-Relieved AlSi10Mg Produced via Laser Powder Bed Fusion Additive Manufacturing

Abstract

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.

High‐Temperature Behavior of the Heat‐Treated and Overaged AlSi10Mg Alloy Produced by Laser‐Based Powder Bed Fusion and Comparison with Conventional Al–Si–Mg‐Casting Alloys

“…[ 43 ] In contrast, the T6R OA –200T loses almost wholly the strain‐hardening ability due to the decrease in the strengthening effect of the Mg 2 Si precipitates induced by the high temperature. [ 24,28,37 ]…”

“…Furthermore, the analysis of the true stress–true strain curves showed strain‐hardening phenomena only at temperatures below 200 °C. Lehmhus et al [ 24 ] observed comparable results on the SR alloy (2 h at 350 °C) tested at 125, 250, and 400 °C, reporting a significant reduction in strength above 250 °C and the dominant effect of temperature on building orientation. Tocci et al [ 25 ] shifted their attention on the L‐PBF AlSi10Mg alloy in AB condition and post‐thermal exposure (10 h at 100 and 150 °C), observing during high‐temperature tensile tests (100 and 150 °C) a slight decrease in UTS , a significant increase in e f , but no effect on YS.…”

“…However, as Lehmhus et al [ 24 ] highlighted, further studies should investigate the effects of thermal exposure on the kinetics of microstructural evolution and overaging phenomena, quantifying the high‐temperature performances of the L‐PBF AlSi10Mg alloy subjected to different heat treatments, that is, direct aging (T5) and solutioning plus artificial aging [AA] (T6).…”

Room- and High-Temperature Fatigue Strength of the T5 and Rapid T6 Heat-Treated AlSi10Mg Alloy Produced by Laser-Based Powder Bed Fusion

“…In particular, high-tech structural components in the transportation and energy industry are subjected to cyclic mechanical loads over a wide range of temperature distribution and mechanical load conditions [5]. Therefore, evaluating the effects of high temperatures on fatigue resistance is essential, particularly given the limited information in the literature [25][26][27].…”

On the Role of Microstructure and Defects in the Room and High-Temperature Tensile Behavior of the PBF-LB A357 (AlSi7Mg) Alloy in As-Built and Peak-Aged Conditions

“…However, the concurrent effect of defects content and heat treatment condition must be addressed. Furthermore, even though a few attempts to assess the high-temperature behavior of AlSi10Mg PBF-LB alloy have been carried out [ 21 , 22 , 23 , 24 ] to the best of the authors’ knowledge, mechanical properties at high temperatures of the A357 PBF-LB alloy have yet to be investigated.…”