Study On Point-mode Forging And Laser Addictive Manufacturing Of TC4/TC11 Microstructures And Properties

Ti-6.5Al-3.5Mo-1.5Zr-0.3Si is also known as TC11 titanium alloy,and Ti-6Al-4V is also known as TC4 titanium alloy.Both titanium alloys are α+β Type titanium alloy and they are widely used in the aerospace field.The traditional laser additive manufacturing technology will form coarse columnar crystals,and the mechanical properties show anisotropy.In this experiment,the point forging laser additive technology is used to design three different pressing methods: pure melting,point forging at the interface,and point forging process throughout the process.The microstructure,tensile properties,microhardness and fracture morphology of three different pressing methods were analyzed and discussed.The experimental results show that with the addition of point forging process,the grains gradually change from coarse columnar grains to equiaxed grains.The pure melting state is coarse columnar crystal,and the grain morphology at the point forging interface is columnar-equiaxed-columnar,and the grains are equiaxed during the whole process of point forging.The internal structure of the grain is basket structure.The yield strength,tensile strength and elongation of TC4/TC11 titanium alloy tensile specimen added by point forging laser meet ASTM B381-2013 titanium alloy standard forgings.After different solution and aging treatments,the strength and plasticity of TC4/TC11 titanium alloy are slightly improved.After solution and aging treatment in different systems,TC4/TC11 titanium alloy αThe phases are spheroidized and coarsened to different degrees,and the grain boundary αAfter solution and aging treatment,the corresponding spheroidized fracture phenomenon also appeared.The following results were obtained by testing the longitudinal tensile properties of the tensile parts with three different compression methods at room temperature: the pure melt state has the best plasticity at 970 ℃ solution temperature,and the highest strength at 930 ℃ solution temperature.The TC4/TC11 titanium alloy with the whole process of point forging shows the best comprehensive properties after970 ℃/2 h/AC+550 ℃/4 h/AC solution aging treatment,and the elongation is the highest under 970 ℃/2h/AC+550 ℃/4 h/AC heat treatment system.The TC4/TC11 titanium alloy at the point forging interface has the best plasticity after970 ℃/2h/AC+600 ℃/4 h/AC treatment,and the highest strength under 930 ℃/2h/AC+550 ℃/4 h/AC solution aging system.