Plastic Control Of NiAl At Room Temperature And Research On Forging Process Of Ribbed Plate Under Current Auxilary

At present,countries all over the world are committed to the development of aerospace field and have higher requirements for the comprehensive properties of materials needed in this field.Therefore,low density and high strength NiAl intermetallic compounds have been widely concerned.NiAl material has such problems as high strength at high temperature,difficult deformation,poor plasticity at room temperature,etc.,which greatly limits the manufacture and application of this material.Based on this topic,rhenium element was added to improve the room-temperature plastic ratio of NiAl intermetallic compounds and the material was heated rapidly by pulse current to assist its forming process.This paper mainly explores the influence of rhenium on the mechanical properties and microstructure of NiAl intermetallic compounds,and the temperature distribution,cavity filling rule and stress distribution in the forging process of NiAl material,which provides theoretical basis and process parameters for the forming process of NiAl structural parts with ribbed plates.NiAl intermetallic compounds containing rhenium with different mass fractions were prepared from Ni,Al and Re powders by hot pressing sintering.The tensile test at room temperature and Gleeble thermal compression test were carried out to determine the optimal addition content of rhenium.The mechanism of adding rhenium with different contents to increase the room temperature plasticity of NiAl intermetallic compounds was studied by analyzing the microstructure,morphology and EDS.It was found that the density and rhenium solubility of the material were increased by the experiments of secondary deformation and heat treatment,and the room temperature plasticity of the material was greatly improved.The electric heating process of the material was simulated by finite element method.The two conditions of heating in air and heating in mold were simulated respectively.Through the simulation the heating law of current heating NiAl plate was explored,and the problem of uneven temperature distribution of the plate caused by clamping of electrode and different cross-sectional area of plate was solved.The electric heating curve of NiAl material was developed and the experiment was guided according to the simulation results.In the actual electric heating process,the temperature of the plate was measured and the feasibility of the simulated material heating curve was verified by the experiment.Based on Gleeble experimental data,Arrhenius constitutive equation was constructed,and its validity was verified by Zenner-Hollomon parameter.The forming process of the sheet metal was simulated by finite element method,the filling rule of the cavity was analyzed,and the shape of the blank and the technological parameters in the forging process were optimized.According to the simulation results,it was determined that the preformed billet had the local rib characteristic structure,which could alleviate the problems of stress concentration in the rib and high pressure during forming.Finally,the Large NiAl sheet metal parts with ribbed features were formed by pulse current assisted forming technology,which provided theoretical guidance and process parameters for the pulse current heating and forging forming technology of NiAl parts with ribbed features.