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采用扫描电镜(SEM)观察了经强流脉冲电子束辐照后45号钢试样上预制的凸台或内孔不同位置处重熔层的相对厚度,研究了凸台高度、内孔深度及侧面坡度对辐照均匀性的影响。研究发现,对于圆柱形凸起,在平行于电子束辐照方向的侧面,也观察到了一定厚度的熔融层,侧面上部熔融层厚度大于下部,随着柱体高度增加,柱体侧面上下部熔融层厚度差异略有增加;对于圆台凸起,随着侧面坡度的增加,熔融层厚度趋于一致。对于圆柱形孔,孔壁上部熔融层厚度远大于孔下部,并且随着孔深度增加,侧壁熔融层厚度不均匀性加剧,孔底部熔融层相对厚度也降低;对于圆台形孔,随着开口尺寸的增加,辐照均匀性增加。结果表明,虽然电子束是视线式发射,但是当电子束到达工件表面时,在自建电场的作用下,电子流会发生偏转,使电子束能量在工件表面重新分布。
Scanning electron microscope (SEM) was used to observe the relative thickness of the remelted layer on the bosses or bores prefabricated on the 45 steel sample irradiated by high-current pulsed electron beam. The effects of the height of bosses, Effect of Slope on Radiation Uniformity. It is found that for the cylindrical bulge, a certain thickness of fusion layer is observed on the side parallel to the irradiation direction of the electron beam. The thickness of the upper fusion layer is larger than the lower one. As the height of the cylinder increases, the upper and lower sides of the cylinder melt The difference of layer thickness slightly increased; for the round table bulge, the thickness of the melt layer tends to be consistent with the increase of the slope of the side. For the cylindrical hole, the thickness of the molten layer in the upper part of the hole wall is much larger than that in the lower part of the hole, and as the hole depth increases, the non-uniform thickness of the molten layer in the sidewall aggravates and the relative thickness of the molten layer in the hole bottom also decreases. As the size increases, the uniformity of irradiation increases. The results show that although the electron beam is a line-of-sight emission, when the electron beam reaches the surface of the workpiece, the electron current will be deflected by the self-built electric field so that the electron beam energy is redistributed on the surface of the workpiece.