Microstructures And Properties Of Consecutive Point-mode Forging And Laser Rapid Forming Repaired TA15 Titanium Alloy

Medium-strength titanium alloy TA15,which has been widely used in aerospace and other fields,has good thermal stability,moderate room temperature and high temperature strength.The technology of laser forming repaired(LFR)has possessed many advantages.However,because of the limitation of LFR technical characteristics,the reduction of the comprehensive mechanical performance are still unavoidable after the repair,which limits the application range.In this paper,the research significance of the new repaired technology for consecutive point-mode forging and laser rapid forming repaired(CPF-LFR)is described.Microstructure,micro-hardness and tensile mechanical properties at room temperature are systematically analyzed and studied by using experimental testing,experimental phenomena,theoretical analysis and comparative experimental research methods.Firstly,the microstructure of samples by laser surface remelting solidified(LRS),LFR and CPF-LFR are analyzed with optical microscope and scanning electron microscope.The CPF-LFR sample contain repaired zone,heat-affect zone and substrate.The result shows the microstructure of the repaired zone by CPF-LFRed TA15 alloy sample is equiaxed grains with continuous grain boundary?phase(?_G)and the equiaxed grain morphology by CPF-LFRed are uniform in shape and size on the basic research of the results of LRS.The volume fraction and size of equiaxed?phase increase with the distance increasing from repaired zone to heat-affected zone.Compared with the results of LFR,the heat-affected zone is reduced in depth due to plastic deformation and deformation distortion energy exists in the structure.Secondly,the TA15 alloy samples by CPF-LFRed were treated at different types of solution heat treatment.The results indicated that the high temperature solution could lead to globular and discontinuous?_G and the degree of globular with temperature increasing is more complete.The micro-sized equiaxed?phase is found between primary equiaxed?phase in heat-affected zone and the volume fraction and size are determined by the storage energy and the solution temperature.The closer the distance to substrate,the higher the solution temperature and the greater the volume fraction and size of micro-sized equiaxed?phase.Finally,the mechanical properties of the samples by CPF-LFRed in the original and different solution temperature treatments are research.The results of micro-hardness test indicates that the hardness distribution of the whole sample in the original state increases from substrate to repair zone and the difference between the two zones decreases after the solution treatment.The 920?solution temperature is the most uniform.The results of mechanical properties at room temperature show that the fractures of the original and heat-treated samples all show ductile fracture characteristics.The solution temperature at920?shows better tensile mechanical properties at room temperature.