In March 2019, China Aerospace's high-end titanium alloy product R & D and production base: HEHT Titanium Alloy Material Technology Group completed the development of TA32 high-temperature titanium alloy powder and laser selection melting forming (SLM) parameter optimization of TA32 powder, which means high-temperature titanium There are new developments in alloy additive manufacturing technology.
In recent years, with the rapid development of the aerospace industry, especially the development of aero engines and hypersonic vehicles, the demand for titanium alloy materials has also increased dramatically. In order to further reduce weight and increase the thrust-to-weight ratio of aircraft, titanium alloys are increasingly used in aircraft engine compressor wheels, blades, integral blade disks, casings and rotors, as well as missile rudder wing skeletons, cabins and engine inlets. Manufacturing of airway and other parts. The continuous improvement of the performance of aerospace vehicles has put forward higher requirements for the use temperature of titanium alloys, and the development of high-temperature titanium alloys is imminent.
TA32 titanium alloy, whose nominal composition is Ti-5.5Al-3.5Sn-3Zr-1Mo-0.5Nb-0.7Ta-0.3Si, is a new type of near-alpha titanium alloy newly developed in China. The material is under high temperature of 550 ℃ It still has good creep and long-lasting properties, and is expected to replace some steel or nickel-based superalloy materials. The short-term service temperature can reach 600 ℃, and it has good comprehensive mechanical properties such as tensile, fatigue and creep. HEHT systematically carried out research work on powder preparation technology and laser selective melting forming technology for TA32 titanium alloy.
Development of Additive Manufacturing TA32 Titanium Alloy Powder
HEHT adopts water-cooled copper crucible vacuum induction melting gas atomization powdering technology to complete the development of TA32 titanium alloy powder. The principle is to use electromagnetic induction heating to achieve the smelting of titanium alloy rods in the water-cooled copper crucible. The molten metal is made by means of bottom injection It enters the diversion pipe to form a stable and fine liquid flow. When the alloy liquid flow flows through the nozzle through the atomizing nozzle, the high-speed air flow generated by the atomizing nozzle is crushed and solidified to form fine powder particles, which has high production efficiency and fine powder. High yield and other advantages.
After testing, the TA32 titanium alloy powder produced by this technology has excellent properties such as high purity, high sphericity, high fluidity, and high bulk density. Various performance tests were carried out on the TA32 with a particle size range of 15-53μm. The oxygen content of the powder was 1000ppm, the nitrogen content was 190ppm, and the hydrogen content was 50ppm. The content of various impurity elements was far below the relevant requirements of the GB / T3620.1-2016 standard. The physical properties of the powder were tested. The median particle size d50 of TA32 powder was 36 μm, the bulk density was 2.4 g / cm3, and the Hall flow rate was 45 s / 50 g. The various performance indicators met the metal 3D printing process requirements.
By controlling the laser energy density, TA32 titanium alloy powder was subjected to laser selective melting 3D printing forming test under different process parameters. The metallographic test results showed that the grain size of the TA32 powder laser selective melting forming specimen was relatively small, without obvious cracks, Defects such as holes. Further test the mechanical properties of the test piece, the results show that the tensile strength and elongation of the sample at room temperature reached 1200MPa and 8%. The test pieces have high-temperature tensile strengths of 867 MPa, 819 MPa, and 712 MPa at 500 ° C, 550 ° C, and 600 ° C; plastic values of 14.4%, 15.9%, and 17.0%, and have excellent mechanical properties.
Established in 2003, HEHT is a titanium alloy material research and production base under the China Aerospace Materials Research Institute, which specializes in high-end titanium alloy product development, design, manufacturing and service. The company's main business includes titanium alloy precision casting, titanium alloy plastic molding, titanium alloy powder preparation and 3D printing, system integration and processing, etc. Since 2018, the company has continued to carry out a large number of TA32 high temperature titanium alloy powder additive manufacturing technology research work, using laser selective melting forming technology for the rapid development of high temperature titanium alloy parts, which has improved material mechanical properties, saved mold costs and processing cycles The advantages of improving material utilization rate and other related research results are expected to have broad application prospects in the aerospace, shipbuilding and chemical industries, and can further promote the popularization and application of high-temperature titanium alloy material additive manufacturing technology.