Progress in Laser 3D Printing Technology of High Strength Aluminum Alloys

[China Aluminum Network] 3D printing technology is rapidly changing the traditional mode of production and lifestyle. As a strategic emerging industry, 3D printing technology integrates digital technology, manufacturing technology, laser technology, and new material technologies, and is known as a representative technology that is expected to become the "third industrial revolution." Metal laser 3D printing technology as the frontier and more potential technology in the entire 3D printing system is an important development direction of advanced manufacturing technology. Among them, the selective laser melting (SLM) technology based on automatic powder coating is mainly characterized by high machining accuracy, almost no mechanical processing, and the ability to directly manufacture various sophisticated metal parts to achieve structural and functional integration and light weight. In the aerospace, biomedical manufacturing and other fields have a wide range of application needs.

At present, the materials used in SLM technology have covered titanium alloys, high-temperature alloys, iron-based alloys, cobalt-chromium alloys, and a small amount of aluminum alloys with low strength. High-strength aluminum alloys, as a lightweight material that is widely used in the industrial field, are increasingly demanding in the SLM field. However, compared with other materials that have been successfully applied to SLMs, high-strength aluminum alloys have higher thermal conductivity and higher reflectivity to lasers, and have a high degree of alloying and a wide range of crystallinity, making the formation of SLM very strong. The hot cracking tendency severely limits its engineering application.

In order to solve the problem of hot cracking of existing high-strength aluminum alloys formed by SLM, Ph.D. students Zhang Hu and Nie Xiaojia, PhD students of the Advanced Laser Manufacturing Research Team of Wuhan Optoelectronics National Laboratory, under the guidance of Prof. Zhu Haihong, proceeded from the perspective of traditional aluminum alloy material design. Through the addition of trace elements in SLM forming high-strength aluminum alloys, dense and crack-free specimens were obtained. In the successful suppression of thermal cracking, the SLM forming efficiency is greatly improved; unlike the original coarse columnar crystal microstructure, the microstructure modified by the trace elements is an equiaxed crystal of the order of 1 mm; the grain refinement and precipitation strengthening Together, the ultimate tensile strength increased by 12%.

The research results break through the bottleneck of the existing SLM technology to form high-strength aluminum alloys, and it is expected to accelerate the industrial application of aluminum alloy materials in the field of laser 3D printing. In June 2017, the study "Effect of Zirconium addition on crack, microstructure and mechanical behavior of selective laser melted Al-Cu-Mg alloy" was published in the metallurgical engineering periodical Scripta Materialia (IF: 3.305, DOI: 10.1016/j). .scriptamat.2017.02.036). The research work was supported by the National Natural Science Foundation of China (No.).

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