表面状态对强流脉冲电子束辐照诱发金属表面熔坑的影响

 为了考察材料晶体学特性对表面熔坑形成机制的影响，利用强流脉冲电子束（HCPEB）对喷丸前、后的304奥氏体不锈钢进行表面辐照处理，对HCPEB诱发的表面熔坑形貌进行了详细的表征。实验结果表明，HCPEB辐照后样品表面形成了大量的火山状熔坑，熔坑数密度和熔坑尺寸随电子束能量的增加而减小，材料表面的杂质或夹杂物容易成为熔坑的核心，并在熔坑形成的喷发过程中被清除，起到净化表面的作用。此外，喷丸前、后样品表面熔坑数密度遵循相似的分布规律，喷丸处理使熔坑数密度显著增大，表明材料的晶体学特性对表面熔坑形成有重要的影响，晶界、位错等结构缺陷是熔坑形核的择优位置。

Influence of Surface State on the Crater Formation of Metallic Material Surface Irradiated by High-Current Pulsed Electron Beam

In order to investigate the influence of crystallographic properties of materials on the formation mechanism of surface craters, high current pulsed electron beam (HCPEB) was used to irradiate a 304 austenitic stainless steel with and without shot peening treatment. The morphologies of surface crater induced by HCPEB were characterized in detail. The experimental results indicate that a large number of volcano-like craters are inevitably formed on the surface sample after HCPEB irradiation. The number density and dimension of craters decrease with the increase in electron beam energy. It is found that inclusions on the surface layer easily become the new nucleation sites of craters; however, they are gradually removed during the period of eruption in the formation of the crater, and showing a surface purification effect. Additionally, it is established that the number density of craters on shot peening samples is significantly increased than untreated ones. The number densities of craters on the samples with and without shot peening treatment follow the similar law. The present results indicate that the crystallographic properties of materials have a great importance to the formation of surface craters, and the structure defects, such as grain boundaries and dislocations are the preferred sites of the nucleation of craters.