Numerical Simulation Study On The Temperature Field Of Ni-Base Superalloy Prepared By Laser Additive Manufacturing

Laser additive manufacturing is a new technology that based on layered manufacturing principle and material accumulation method to turn CAD models into solid parts.Compared with traditional cutting techniques,the techniques have a series of advantages such as easy to realize digital manufacturing,no need for mould clamping device,not limited by the structure of parts and high material utilization,therefore,in aerospace,automobile manufacturing,electronic products,medical devices and other industries have wide application prospects.The study on laser additive manufacturing technology is mainly to study the distribution of temperature field in the manufacturing process.However,it is very difficult to measure the temperature of molten pool in real time,thus,the law of temperature change is difficult to grasp,and it need a lot of experimentation to find the pattern.So it is going to cost a lot of times,therefore,the study on the temperature change rule in the process of laser additive manufacturing by means of experiment is not very maneuverable.The development of numerical simulation software provides a very convenient method to solve this problem.In this paper,ANSYS numerical simulation software is used to simulate the process of laser additive manufacturing by using its heat source mobile and “life and death unit” technology.Firstly,using the finite element to simulate the temperature field,and take the temperature field simulation results as known conditions for simulate the strain and stress field,to obtained the stress and strain evolution of the parts in the process laser additive manufacturing.In this paper,it will to simulate the manufacturing process of rectangle model and thin-walled cylinder model.The parameters such as laser power,scanning speed and spot diameter are kept unchanged,and the temperature field distribution under different conditions is obtained by changing the thickness of the cladding layer and the curvature of the model.By simulation the stress field and strain field distribution,to detailed understanding of laser gain material temperature field in the process of the overall distribution and thickness of cladding layer,parts of curvature in the cladding process parameters such as temperature field,the influence of the stress and strain distribution rule.Through the analysis of the simulation results,it is found that the distribution of temperature field is a dynamic process with the increase of the number of cladding layers.For each the coordinates on the time dimension mutation process,there is a temperature and peak temperature twice to melting temperature of the metal powder,so that we can make the upper and lower two layers of metal powder to the metallurgical combination of corresponding points.The decrease of the layer thickness and curvature produced will have obvious effect on heat transfer,especially when the thickness of the cladding layer are decreased,is advantageous to the heat transfer,but the increase of cladding time,affect the manufacturing efficiency.In material manufacturing parts of small volume,low altitude,the heat loss path mainly for Z direction(height)in the direction of the heat dissipation,leading to the Z direction of the temperature gradient is larger,the molding parts is easy to form along the Z direction of the columnar crystal growth.Through the analysis of the simulation results of the stress and strain,found in the cladding in the beginning,tied to cladding layer and substrate,the heat transfer between them is very strong,lead to the severe temperature gradient is very high,but due to the constraint of threatening the cladding layer,which will produce larger thermal stress,and give priority to with tensile stress.When it exceeds its yield strength,it will cause the parts to deform,and when it exceeds its ultimate tensile strength,the cladding parts will crack at the root.