Study On Shape Control Process Of 316L Stainless Steel Solid Forming By Laser Cladding

Laser cladding forming is a new technology of material increase manufacturing,which has been widely used in aeronautics,astronautics,medical,biological,auto manufacturing and other fields.The process of laser cladding forming has a great influence on the size and shape of the forming parts.It is important to control the process reasonably.At present,the related studies are mainly focused on the influence of process parameters on the shape of single channel monolayer cladding layer,and the influence of overlap ratio on the shape of monolayer cladding layer.Study on other processes such as laser scanning path and Z-increments are not thorough enough.Most of the current study methods are focused on the experimental level,which has a large data requirement.A large number of experiments are time-consuming and laborious.In addition,the results have a low adaptability for different materials or different laser cladding systems.Therefore,studying the shape control process such as laser scanning path and Z-increments by simulation and calculation is necessary.Laser scanning path selection of single layer is studied in this paper.The influence of scanning path on temperature distribution is studied by numerical calculation.Molten pool temperature of boundary under same direction cladding is about 300 degrees Celsius lower than that under different directions cladding.Molten pool temperature of boundary under different sides cladding is about 500 degrees Celsius lower than that under same side cladding,which under the parameters of laser power 1000 W,scanning speed 5mm/s,powder feeding quantity 9.15g/min,scanning interval 1.5mm,substrate size 40 mm×30 mm×7mm.The results show that molten pool temperature under same direction cladding and different sides cladding is more stable.Molten pool temperature of boundary under different directions cladding and same side cladding exceeds the normal value.Molten pool temperature affects the height and width of the cladding layer.The temperature of molten pool and the characteristics of cladding layer under different scanning paths are compared through real experiment.Molten pool temperature under same direction cladding and different sides cladding is more stable,and surface flatness of cladding layer is better.The experimental results agree with the simulation results.Defocused amount and Z-increments selection is studied.Powder density distribution model of laser cladding system with coaxial-powder feeding is established based on the probability theory.The calculation formula of cladding height under different negative defocused amounts is given and experimental verified.Calculations of cladding height under different negative defocused amounts are in accordance with experiments.The calculation method of multi-layer cladding thin-walled part height under any defocused amount and Z-increments is proposed and experimental verified.Calculations of multi-layer cladding thin-walled part height are in accordance with experiments.Finally,the selection method of defocused amount and Z-increments for laser cladding forming fixed height solid parts is given.Solid forming experiment of 316 L stainless steel cube block is carried out.The results show that the dimensional accuracy and surface flatness of the forming parts can be improved in 316 L stainless steel laser cladding solid forming by selecting the shape control process which is proposed in this paper,and the comprehensive quality of forming is improved.