45号钢脉冲电子束熔凝处理及微结构研究

利用多极板赝火花放电装置产生的高功率脉冲电子束对45号钢进行轰击,通过扫描电子显微镜(SEM)和透射电镜(TEM)的观察,研究了电子束在金属表面和纵向深度上引起的组织结构的变化。结果表明轰击区表面瞬态骤熔急冷,形成了微晶或无序层;剖面组织区域分为熔凝区,马氏体区,热影响区和基体。熔凝区在极高的温度梯度下,具有自淬火效应。马氏体区和热影响区在多脉冲的作用下,相当于经历了多次退火和回火过程,材料组织明显细化。轰击后样品表面的显微硬度与耐腐蚀性测试结果表明,显微组织的细化,改善了金属材料表面的物化性能。采用适当的脉冲数对金属材料表面改性作用效果明显。

Study on Microstructures of Pulsed Electron Beam Remelted Carbon Steel 45

High power density electron beams generated by multiplate pseudospark discharge chamber have been used for bombardments of 45# steel.The transformations of microstructure both on metal surface irradiated by electron beams and along it's lengthways depth have been studied in this paper by SEM and TEM.The results showed that metal surface of bombardment region had been melted quickly,cooled and resolidified abruptly,finally became microcrystalline structure or disordered structure.The section has been divided into melting zone,martensite zone,heat affected zone and base metal.Melting zone was self-quenched under high temperature gradient.Martensite zone and heat affected zone was experienced many times of annealing or tempering processes at the bombardment of multiple pulses so that make crystal grains refined distinctly.The results of microhardness and corrosive resistance showed that mechanical properties of surface layer have been improved due to the refined grain.It is concluded that pulsed electron beam is beneficial to metal surface modification.