Research On Embossing Technology Of Micro-pit Array On Zr2 Zirconium Alloy Surface

Surface microfeature has broad application prospects in the fields of automobiles,aerospace,energy and high-end equipment,etc.In the transmission parts of automobiles and high-end equipment,the surface of friction pair is processed micro pits with certain size and regular arrangement,which can reduce friction and wear of the interface and improve bearing capacity and life span.In the aerospace field,the surface processing microfeatures can reduce the eddy currents of interface gas.In the nuclear energy element,the surface processing microfeatures can improve the heat transfer property of the interface.Therefore,the research of high-efficiency and high-quality surface microfeature preparation technology is of great significance.Based on the high-efficiency and high-accuracy micro-pit embossing forming process on the surface of Zr2 zirconium alloy plate,this paper conducts systematic research on the material properties,micro pit design,force parameters and forming qualities and provides the theoretical basis.The main research contents are as follows:(1)Building Zr2 zirconium alloy material constitutive model.Firstly,Obtained the room temperature mechanical properties of Zr2 zirconium alloy plate by MTS fatigue tensile test.Then,developed the Zr2 zirconium alloy material constitutive equation based on the experimental data and the four classic material models of Johnson-Cook,Hollomon,Voce,and Hockett-Sherby.Finally,Compared and analyzed the constitutive model mean square error,residual square error and other parameters to determine the optimal Zr2 zirconium alloy material constitutive model.(2)Research on the mold micro pit design method based on formability.Firstly,three mold micro pit structures of quadrangular pyramid surface,spherical surface and conical surface are proposed based on the micro pits design requirements.Then,carried out the mold micro protrusions geometric design and material selection according to the geometric characteristics and distribution density of the micro pits.Finally,analysis and comparison of the three kinds of micro pit embossing forming processes for material flow,forming load,stress distribution and manufacturing process were performed by the software DEFORM-3D to select the optimal micro pit design method.(3)Carrying out research on the force energy parameters of Zr2 alloy plate micro-pit embossing: Based on the principle of metal forming,a theoretical calculation model for the maximum forming force of the embossing process is established;Using DEFORM-3D to carry out numerical simulation,the influence of embossing process parameters and micro-pits geometric parameters on forming force is analyzed by single factor variable method.The comparison between theoretical calculation results and finite element calculation shows that the relative error between the maximum forming force calculation model and the finite element calculation is 13.6%.(4)The influence factors of defects in micro-pit imprint forming of zr2 were studied: the surface collapse rate is proposed as a quantitative indicator of defects.According to the metal material flow process,the defect generation mechanism is analyzed.(5)Carry out experimental research on micro-pit imprinting of zirconium plate:design an experimental plan,combined with orthogonal experiment method and micro-pit embossing test,and obtain the changing law of forming force in the process of impression;through the quality analysis of micro-pit formation,it is proved The feasibility of the embossing process lays the foundation for the next step of engineering experiment design.