Simulation Of Temperature Field And Formation Of Craters Irradiated By High Current Pulsed Electron Beam

This article used finite element simulation to calculate the temperature field ofthe sample in the process of irradiation by high current pulsed electron beam（HCPEB）.40Cr、45#、1Cr13steel and pure silver was irradiated in rapid heating ofsurface in different parameters and the surface morphology and the thickness ofremelted layer was characterized using SEM and metalloscope. The accuracy of theresults of simulation was confirmed by the experimental result. The formation of thecrater-like defects was simulated by carbide impurities model.The result of simulation of pure Fe illustrate that the thickness of remeltedlayer was2.1μm and the molten state of the surface last2.7μs when the irradiationenergy density is5J/cm². The increasing and decreasing rate of the temperature wasabout10⁷-10⁹℃/s and the temperature gradient could reach the magnitude of108℃/m. When taking emissivity of the materials into account, the result changed alittle.In order to study the influence of thermal properties to the temperature field,different specific heat, thermal conductivity and density of materials was designed.The result showed that these factors have great influence in increasing anddecreasing rate of temperature, the temperature gradient and heat flux. Comparedthe simulated result and experimental results of40Cr and45#steel, the results werein good agreement when the accelerating voltage was low; while the experimentalresults was larger than the calculated one when the accelerating voltage was over30kV.After the irradiation of HCPEB, crater-like defects formed on the surface layerof40Cr,45#and1Cr13steel. The dimension of the craters was about50μm anddifferent materials had different number density of craters. But the craters didn’tappear on surface layer of pure silver in same parameters, while only some grainboundaries that arranged irregularly was observed. The component analysis of thebottom area of crater showed that the carbide occupied a great composition. Themodel of Fe₃C particle and Fe substrate was created. The result could be concludedthat the energy gathered between the surface and carbide while the highesttemperature point was on the surface of the substrate just over the Fe₃C particle. Thecalculated results also indicated that the craters were created by the eruption overthe low thermal conductivity impurity particles. When the dimension of carbidebecame larger or the position was closer to the surface, the crater-like defect was more likely to appeared on the surface of the substrate...