The Microstructure And Properties Of TC11Titanium Alloy By Directed Laser Deposition

Directed Laser Deposition (DLD) makes use of the high power and high density laser beam to make the work surface melted slightly with the rapid heating approximate adiabatic in a very short period of time. And with the method of coaxial powder-feed, it can make the deposition powder and the substrate surface melt and solidified, so that we can obtain the as-deposited samples dense and metallurgical bonded with the matrix to restore the geometry size of the parts or to strengthen the surface properties.TC11titanium alloy (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) is a α+β refractory titanium alloy with good comprehensive properties. TC11has high tensile strength and yield strength at room temperature and excellent performance under500℃. In addition. All these characteristics make TC11an ideal material for aerospace engine blades and the aircraft structure.Because of the high melting point and the narrow thermal processing temperature range, the Titanium alloy structural parts used in industry must be processed after plastic deformation. So the processing cycle is long, and the material utilization is very low. To produce the titanium structural components by directed laser deposition technology could shorten the processing cycle greatly, improve the utilization of powder material, save the expensive processing costs.The experiments was completed in Science and Technology on Power Beam Processes Laboratory, AVIC Beijing Aeronautical Manufacturing Technology Research Institute. With the basic study on the DLD formed TC11titanium alloy, the influence of the processing parameters of the directly laser depositing manufacture, including output power, overlap ratio, single-layer distance AZ of Z axis, and also different heat treatment procedure, on the microstructures and mechanic properties of TC1titanium alloy were analyzed. On that basis, the structures and mechanic properties of the TC11itanium alloy fabricated by laser hybrid manufacturing under depositing state and different heat treatment state were investigated. The main results and conclusions of the research are as follows:The microstructure of TC11itanium alloy deposited by Directed Laser Deposition was obvious columnar-like crystals. Furthermore, the directional growth columnar crystals run through multiple deposited layer and was typical widmannstatten microstructure inside.After the heat treatment of duplex-annealing, there was typical basketweave microstructure in the microstructure of TC11itanium alloy; and the hardness and the strength declined slightly, but the plastic deformation improved significantly.While after hot isostatic pressure and duplex-annealing, part of The columnar-like crystals will recrystallize and transferred into bulky isometric crystal. The microstructure was typical widmannstatten structure. Compared with the as-deposited of TC11itanium alloy and the duplex-annealing of TC11itanium alloy, the TC11itanium alloy hardness and the strength of hot isostatic pressure and duplex-annealing declined, the plastic deformation and thotoughness improved significantly.With the distance far from the boundary, the duplex microstructure of TC11itanium alloy produced by laser hybrid manufacturing turned into the widmannstatten structure microstructure. After hot isostatic pressure and duplex-annealing, the microstructure of TC11Titanium alloy changed from the basketweave microstructure to the coarse Widmanstatten microstructure.After hot isostatic pressure and duplex-annealing, the hardness of TC11itanium alloy produced by laser hybrid manufacturing technology were higher than that of deposited by Directed Laser Deposition and the TC11itanium forgings. Compared with the duplex-annealing TC11itanium alloy, the plastic deformation of laser hybrid manufacturing TC11itanium alloy was better than hot isostatic pressure and duplex-annealing TC11titanium ailloy.After experiments, the paper gained various channels to control of the pores defects and the non-fusion defects:optimize the TC11titanium alloy Directed Laser Deposition process parameters, control the powder quality, and process with hot isostatic pressing. While the paper achieved the ways to regulate and control the microstructure and properties of TC11titanium alloy. The base data accumulation of laser hybrid manufacturing TC1titanium alloy could serve with the laser repar apply application.