China's leading magnesium-aluminum alloy manufacturer ZCGY Light Alloy Technology Group, together with the Powder Metallurgy Research Institute of Central South University and the University of Auckland in New Zealand, jointly developed an aluminum-magnesium alloy material suitable for SLM preparation process with good crack resistance and high strength.
Aluminum and its alloys are one of the most widely used structural materials in engineering. They are processed through traditional manufacturing processes such as casting, forging, and powder metallurgy. They often have higher manufacturing costs and longer lead times. Manufacturing defects, such as chemical, also greatly limit its application. Therefore, micro-structure control and strength design have become the research hotspots in the field of 3D printing.
The high-strength aluminum-magnesium alloy material developed by the researchers for 3D printing has a tensile strength of 550 MPa and plasticity between 8% and 17% after aging treatment.
According to reports, the R & D team designed a series of aluminum-magnesium alloy materials and used atomized alloy powder for 3D printing preparation. The results show that adding 1.3wt% of Si to the aluminum-magnesium alloy can effectively suppress the thermal cracking in the SLM process, and at the same time refine the microstructure of the prepared alloy, thereby improving the mechanical properties of the printed samples. Through further fine-tuning of the alloy composition, the researchers designed a new alloy Al-8.0Mg-1.3Si-0.5Mn-0.5Sc-0.3Zr. This new alloy has a clearly refined microstructure, high-density stacking faults and a unique 9R phase are formed in the printed sample. The tensile strength and elongation of the sample reached 497 MPa and 11%, respectively. After aging treatment, the tensile strength of the sample reached 550MPa, and the plasticity was between 8% and 17%. In addition to solid solution strengthening, grain boundary strengthening and nanoparticle strengthening, high-density stacking faults also contribute to strengthening.
The research results of adding Si element to the original 3D printing Al-Mg-Sc-Zr alloy formed a fine printing microstructure, and obtained a crack-free printing alloy composition. Subsequently, a high-density stacking fault and fine grains were introduced through the heat treatment aging process, and a new aluminum-magnesium alloy with low thermal cracking sensitivity and high strength was developed. This work provides an aluminum-magnesium alloy composition design method and heat treatment process that solves and eliminates metallurgical defects in the SLM process, and promotes the engineering application of SLM manufacturing technology.