Abstract
Al-Mg alloys can reach medium strength without a solid solution and quenching treatment, thereby avoiding product distortion caused by quenching, which has attracted the attention of wire arc additive manufacturing (WAAM) researchers. However, the mechanical properties of the WAAM Al-Mg alloy deposits obtained so far are poor. Herein, we describe the preparation of Al-Mg-0.3Sc alloy deposits by WAAM and detail the pores, microstructure, and mechanical properties of the alloy produced in this manner. The results showed that the number and sizes of the pores in WAAM Al-Mg-0.3Sc alloy deposits were equivalent to those in Al-Mg alloy deposits without Sc. The rapid cooling characteristics of the WAAM process make the precipitation morphology, size, and distribution of the primary and secondary Al3Sc phases unique and effectively improve the mechanical properties of the deposit. A primary Al3Sc phase less than 3 μm in size was found to precipitate from the WAAM Al-Mg-0.3Sc alloy deposits. The primary Al3Sc phase refines grains, changes the segregated β(Mg2Al3) phase morphology, and ensures that the mechanical properties of horizontal and vertical samples of the deposits are uniform. After heat treatment at 350 °C for 1 h, the WAAM Al-Mg-0.3Sc alloy deposits precipitated a secondary Al3Sc phase, which was spherical (diameter about 20 nm) and had high dispersity. This phase blocks dislocations and subgrain boundaries, causes a noticeable strengthening effect, and further improves the mechanical properties of the deposits, up to a horizontal samples tensile strength of 415 MPa, a yield strength of 279 MPa, and an elongation of 18.5%, a vertical samples tensile strength of 411 MPa, a yield strength of 279 MPa, and an elongation of 14.5%. This Al-Mg-Sc alloy is expected to be widely used in the WAAM field.
Highlights
Wire arc additive manufacturing (WAAM) has exhibited unique advantages in large-scale component manufacturing due to its high material utilization rate, high deposition rate, low production and equipment cost, and high equipment flexibility and scalability [1,2,3]
WAAM has a higher cooling rate, and Figure 4 shows the metallographic structures of the Al-Mg alloy and Al-Mg-0.3Sc alloy deposits, the morphology and fine grain effect of the primary Al3Sc phase are unique
Which reveal that the deposit grains were strongly refined by the addition of Sc due to the precipitation of Figure 4 shows the metallographic structures of the Al-Mg alloy and Al-Mg-0.3Sc alloy the primary Al3 Sc phase during the WAAM process
Summary
Wire arc additive manufacturing (WAAM) has exhibited unique advantages in large-scale component manufacturing due to its high material utilization rate, high deposition rate, low production and equipment cost, and high equipment flexibility and scalability [1,2,3]. Al-Cu alloy, Al-Cu-Mg alloy, and Al-Si-Mg alloy [4,5,6,7]; excellent mechanical properties have been obtained from these alloys These alloys require solution quenching and aging treatment. Metals 2020, 10, 320; doi:10.3390/met10030320 www.mdpi.com/journal/metals mainly include the Al-Cu alloy, Al-Cu-Mg alloy, and Al-Si-Mg alloy [4,5,6,7]; excellent mechanical properties have been obtained from these alloys Al-Mg alloys can reach medium strength (tensile strength 310–350 MPa [8]) without a Metals 2020, 10, 320 solid solution and quenching treatment, WAAM of Al-Mg alloy parts can avoid product distortion caused by quenching and can provide rapid manufacturing. RealizedAt due to the fast cooling rate the fully due to Al the fast cooling rate of the present, no research hasofbeen
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