| Major components in the marine and offshore engineering fields(deep-sea submersibles,offshore platforms,marine gas turbines,etc.)have large metal components and small batch sizes.If traditional manufacturing methods are used,not only manufacturing difficulties,but also high cost,low efficiency,and large structures are available.It can’t even be made.The additive manufacturing technology breaks the complex production process of the original design-casting-forging/rolling-machining,and becomes a short-flow mode from design to additive manufacturing,with extremely complex component manufacturing capabilities for high-performance components.Integrated manufacturing of material structures provides technical support with the advantages of low cost and high efficiency.At present,the laser fuse additive manufacturing technology represented by titanium alloy material is still in the basic research and development stage.The additive forming parts have problems of low forming precision,step effect and low surface roughness,and often require subsequent reduction.Material processing to meet part quality and accuracy requirements.In this paper,Ti-6Al-4V titanium alloy was studied.The thermal stress field of Ti-6A1-4V titanium alloy during laser fuse deposition was explored by establishing a complete thermo-mechanical coupling model of laser fuse additive manufacturing process.The law of change.Based on the developed numerical model,the influence of process parameters on the temperature field and stress field of the additive during the manufacturing process was studied.Investigate the variation of temperature field distribution and stress-strain field when process parameters change,and predict possible manufacturing defects such as cracks and deformation.Based on the single-layer single-channel simulation results of titanium alloy,a numerical model for the manufacturing process of titanium alloy thin-walled laser fuses was established.The thermal cycling characteristics and thermal stress evolution of the members under cyclic and long-term thermal cycling were studied.Based on the developed model,the effects of deposition direction and interlayer residence time on the evolution of thermal stress field,thermal cycling characteristics and residual stress distribution during thin-walled forming are investigated.Based on the simulation results of additive manufacturing process,the finite element model of the milling process of additive parts was established,and the milling performance of additive parts was studied and explored.Predict the results of milling force,cutting temperature,residual stress etc,and study the influence of process parameters(cutting depth,initial temperature,etc.)on the milling performance of titanium alloys.The main research contents of the thesis include:(1)Based on ABAQUS software,a complete thermo-mechanical coupling numerical simulation method for predicting the temperature field and stress field variation of Ti-6Al-4V titanium alloy laser fuse additive manufacturing process was developed.The variation law of thermal stress field in single-layer single-layer deposition process was studied and analyzed.The effects of laser process parameters and substrate preheating temperature on temperature variation characteristics and residual stress of forming parts were analyzed.(2)The finite element model of the manufacturing process of laser fuses in titanium alloy thin-walled parts was established.The temperature field and stress field cycle characteristics during the deposition process of thin-walled parts were studied.The deposition direction and interlayer residence time were analyzed during the deposition process of thin-walled parts.The influence of temperature field and residual stress distribution.(3)The numerical simulation of the milling process of titanium alloy thin-walled parts was carried out,and the results of cutting force,cutting temperature and residual stress were predicted.The milling performance of titanium alloys with different process parameters(cutting depth,initial temperature,etc.)was investigated.The impact and comparison with the traditional forging milling performance.It provides theoretical basis and reference for the manufacture and milling of titanium alloy laser fuses. |
