Thermodynamic Analysis And Thermal Deformation In The Process Of Laser Additives Manufacturing Metal Parts

Laser deposition manufacturing technology is an advanced manufacturing technology that combines the advantages of laser cladding and rapid prototyping,enabling the direct near-net forming of complex parts without the need for pre-machining of blanks,and provides good processing quality has broad application prospects in the development and production of high-end equipment.Therefore,this research aims at observing carefully the phenomena generated in the laser additive manufacturing process,in the background of the laser additive manufacturing and repairing metal parts,and deeply studying its forming mechanism and influence law by a large number of forming experiments and corresponding numerical simulations.It also analyzes systematically the influence of temperature field and stress field on the quality and microstructure of the formed parts during the laser additive manufacturing process.The main research contents are as follows:(1)Discuss the theory of heat conduction,laser energy conduction and metal thermal deformation during laser cladding,and analyze the principle of laser cladding.Based on the finite element theory and the unit life and death technology,a laser cladding finite element model is established by selecting a reasonable heat source model,powder absorption rate and physical properties of metal materials.(2)For the repair of specific metal parts by laser cladding,it is necessary to use different metal powders for cladding,and analyze the influence of different materials on the temperature field and stress field during laser cladding.By using different materials to simulate the laser cladding process,the influence of different materials on the temperature field and stress field of laser cladding process is analyzed,and a reasonable processing plan is planned.(3)Aiming at the defects such as cracking,remelting,burrs and collapses during laser cladding,it is proposed to reduce the influence of thermal stress on the forming specimen by changing the processing method.By using variable power processing and changing the scanning path,the heat accumulation effect in the laser cladding process is reduced,the temperature gradient of the forming sample is reduced,the elastic hot compression deformation and the heat shrinkage stress during the processing are reduced,and the qualityof the formed sample is improved.(4)For the laser cladding simulation results,the simulation accuracy is verified by performing actual laser cladding processing.The temperature of the molten pool and the residual stress on the surface of the sample after measurement are measured by a non-contact infrared camera and an X-ray diffraction stress tester to verify the accuracy of the simulation,and the simulation results of the macroscopic outer surface and the deformation amount of the substrate are observed.Then,by observing the crystal structure of the shaped sample,we summary the effects of different processing methods on the microstructure of the shaped sample.