The advantage of forging is to achieve metallurgical results with dense internal and relatively uniform structure, and its performance is higher than that of die castings, cutting and welding parts. The purpose of aluminum alloy forging is mainly to improve metal plasticity and reduce deformation resistance. For aluminum alloys that can be strengthened by heat treatment, such as duralumin, forged aluminum (6061, 7075, etc.) and super duralumin, quenching aging is the final form of heat treatment.
Achieving a fine-grained microstructure and having a material strength comparable to that of forged materials. The high-strength 7A77.60L aluminum powder for 3D printing developed by HRL Laboratories was officially put on the market. Users can purchase this aluminum alloy material directly from HRL.
Avoid cracks and achieve high strength
When aluminum alloy materials Al7075 and Al6061 are used, metal 3D printing in a laser high-energy environment can cause severe thermal cracks on metal parts. HRL researchers chose zirconium-based nanoparticle nucleating agents with the help of software and big data , And combined them into 7075 and 6061 series aluminum alloy powder.
The formed material is crack-free and equiaxed (that is, the grains are approximately equal in length, width, and height), achieving a fine-grain microstructure and having material strength comparable to that of forged materials. 3D printed aluminum alloy materials yield on average The strength is up to 580 MPa, the ultimate strength exceeds 600 MPa, and the average elongation exceeds 8%.
After successfully developing nanoparticle nucleating agents in 2017, HRL faced the problem of how to obtain technical protection while commercializing this technology. In 2019, HRL registered aluminum powder for additive manufacturing alloys with the Aluminum Association of America. The HRL registration number is 7A77.50 and the alloy registration number is 7A77.60L.
By commercializing the materials, HRL achieved a perfect combination of the high strength obtained by 3D printing aluminum alloy materials and the freedom of design. This aluminum alloy material is suitable for the processing of high value-added products, including aerospace, automotive, oil and natural gas.
Renishaw, a UK-based 3D printer supplier, selected laser melting 3D printing equipment as the first machines to be proven capable of handling 7A77. Based on Renishaw's equipment, users can focus on further optimizing parameters for their unique production components.
With the popularity of 7075 aluminum alloy in aircraft manufacturing, aerospace naturally became the first industry to start using HRL's 7A77 metal powder. According to the market observations of 3D Science Valley, the application of aluminum alloy powder for HRL additive manufacturing in the aerospace field to date includes the production of pressure vessels, manifolds, brackets and other fuselage parts. On-demand maintenance of aircraft is also a particularly promising area. Of course, this material also has untapped potential in the fields of oil and gas, automobiles and sporting goods.
Since strength is not the only standard for engineering applications, HRL Laboratories is now improving the corrosion resistance, fracture toughness and fatigue strength of 7A77. The technology used to develop 7A77 is also used in 2000 and 6000 series aluminum alloys, and the laboratory is expected to be put on the market in the near future.
Other related high-performance aluminum powder 3D printing materials
The R&D team of SZBF Alloy Material Technology Company: Academician Wu Xinhua of the Australian Academy of Engineering led the research team of Monash University to successfully develop a special aluminum alloy material with the brand of Al250C for high-strength and high-toughness additive manufacturing, adding a star member to the 3D printing aluminum alloy . Al250C is a material specially designed by the research team for 3D printing, and has reached the stage of mass production and commercial use. The strength of the Al250C material reaches the highest level among the aluminum alloy materials currently available for 3D printing, the yield strength can reach 580MPa, the tensile strength is above 590MPa, and the elongation can reach 11%. The prepared component has passed the stability test at 250℃ for 5000 hours , Equivalent to the requirement of 25 years of regular engine service.
The British-based foundry expert Aeromet International patented aluminum alloy powder A20X for additive manufacturing has produced parts that have exceeded the ultimate tensile strength (UTS) of 500 MPa. Aeromet claims that this achievement makes the aluminum alloy material "one of the strongest aluminum alloy powders commercially available for additive manufacturing." A20X is an aluminum-copper alloy material with a fine microstructure. Compared with other alloys, it has “high strength, fatigue resistance and optimized thermal properties.” Currently, Metal Material Characterization Development and Standardization (MMPDS) and Approved by the Aerospace Material Standard (AMS), this material has been adopted by the world's leading aerospace casting suppliers.
Nanjing University of Aeronautics and Astronautics developed aluminum-based nanocomposites based on SLM a few years ago, which are used in the field of laser additive technology to effectively solve the mismatch and enhancement of the process performance and mechanical properties of aluminum-based nanocomposites during the laser additive process. The problem of uneven particle distribution and poor wettability between the ceramic phase and the substrate phase make the obtained product have good interface bonding and excellent mechanical properties.
In short, the emergence of high-strength aluminum alloy materials for 3D printing has opened a brand new door for parts processing that had to be achieved by forging. Combined with the freedom of design released by 3D printing, high-strength aluminum alloys will include pressure vessels, The field of hydraulic manifolds, brackets and high-strength structural parts gains huge market space for imagination