| With the continuous progress of science and technology,many new technologies keep emerging in the field of manufacturing technology,and manufacturing technology has also undergone great changes.In recent years,additive manufacturing has become a hot research topic at home and abroad.Laser cladding forming is one kind of additive manufacturing,which has attracted a lot of attention at home and abroad.Laser cladding technology is a kind of technology that uses laser as heat source to melt alloy powder.After the laser heat source is removed,the melted alloy powder solidifies rapidly,and it is used to remanufacture waste parts and form parts through horizontal and vertical lapping and path planning.In this paper,the research was based on RCF104 iron-base alloy powder materials.Firstly,the experimental equipment,powder materials and substrate materials are introduced.The interaction between laser and substrate and powder materials was briefly introduced.Then,the simulation study of single-track temperature field,optimization of single-track process parameters,horizontal lap rate and vertical lap rate were carried out,the micro structure was analyzed and the properties test experiment was carried out,and finally the laser cladding forming of structural parts was carried out.The main research contents are as follows:(1)Simulation of single-track laser cladding temperature field.Under the conditions of 380w laser power,6mm/s scanning speed and 0.6mm laser beam radius,the single-track laser cladding temperature field was simulated by ANSYS software and the temperature field of different load steps was analyzed.The influence of laser power,scanning speed and laser beam radius on temperature field was studied.(2)Single factor experiments,orthogonal experiments were carried out to select the optimal process parameters and optimize vertical horizontal lap rate.Single factor experiments were carried out to study the influence of laser power,powder feed,scanning speed and defocus on the geometric parameters of single-track.The range of parameters was selected for the orthogonal test.The influence of process parameters on the cross-section was studied by range variance analysis,and the optimal process parameters were selected by comprehensive analysis method.According to the principle of equal volume,the horizontal and vertical lap rate models are established.The lap rate experiments were carried out to select a better lap rate.(3)Study on microstructure and properties of cladding layer.The microstructure of single-track cladding layer,single-layer multi-track cladding layer and three-layer multi-track cladding layer were analyzed.MH-6 microhardness tester was used to test the horizontal and vertical microhardness of single cladding layer and the microhardness mean value was calculated.The microhardness of three-layer multi-track of bottom layer,middle layer and top layer,the microhardness of bottom layer and middle layer overlapped zone,and the microhardness of top and bottom overlapped zone and non-overlapped zone were tested.The wear resistance of single layer,double layers,triple layers and substrate was tested by friction and wear experiments.The three layers multi-track cladding layer was taken as a sample to analyze the cladding layer by EDS.The defects in laser cladding are analyzed and the improvement measures are put forward.(4)Study on the forming of parts.The laser cladding forming of the thin-walled ring and incline thin-walled wall was carried out,the forming path of the thin-walled ring was optimized,and the influence of changing starting point in the same direction and changing starting point in the opposite direction on the inner and outer diameter of the ring was analyzed.The stacking model and the maximum tilting capacity model of incline thin-walled wall are established.The forming experiments were carried out and the angle of inclination was measured.The results show that the forming quality is good and the error is small. |
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