Abstract—

Specific features of fabricating welded structures of the international thermonuclear experimental reactor (ITER) blanket components are considered. The results from elaborating the technology for electron-beam welding of cooling system’s channel caps in the first wall bearing structure (FWBS) of the ITER blanket shielding module are presented. The design of welded joint samples made of Grade 316L(N) steel and the welding equipment are described. The welding techniques and butt joint design features whose use makes it possible to obtain the required strengthening of weld bead and to avoid metal droplets from appearing in the FWBS inner cavities are considered. A simplified thermal–mechanical model of the cap-welding technological process is described, and the results from experimentally evaluating the structural and mechanical state of the obtained welded structures are presented. A comparison between the modeling and experimental results is given. It is pointed out that the stressed and strain state varies in an active manner at the initial loading stage. Initially, the metal in the heat-affected zone (HAZ) experiences plastic deformation followed by elastic relief at the subsequent stages. It is pointed out that the postweld deformations are on the whole characterized by a low level and remain within the permissible limits. The distribution of mechanical properties in weld joint local zones determined using the indentation method is given. The results from tensile tests and an indenter impressing test show that the weld metal has even better mechanical characteristics than the parent metal. Data are presented from metallographic investigations, which testify that there is no growth of grains in the HAZ, which is due to high rates of cooling in the used welding method. Based on the results of elaborating the electron-beam welding technology and using the developed techniques, an FWBS mockup has been fabricated that complies with the class VQC 1A tightness requirements.

中文翻译：

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ITER毛毯第一壁组件的电子束焊接的特殊功能

摘要—

考虑了国际热核实验反应堆（ITER）毯组件的焊接结构的特定特征。阐述了详细阐述了ITER毯式屏蔽模块的第一壁支承结构（FWBS）中的冷却系统通道盖的电子束焊接技术的结果。描述了由316L（N）级钢制成的焊接接头样品的设计和焊接设备。考虑了其焊接技术和对接设计特征，这些特征的使用使得可以获得所需的焊缝强化并避免金属滴出现在FWBS内腔中。描述了帽盖焊接工艺过程的简化热力学模型，给出了通过实验评估获得的焊接结构的结构和力学状态的结果。给出了建模和实验结果之间的比较。要指出的是，应力和应变状态在初始加载阶段以主动方式变化。最初，热影响区（HAZ）中的金属经历塑性变形，随后在后续阶段进行弹性释放。要指出的是，焊后变形总体上以低水平为特征并且保持在允许的范围内。给出了使用压痕法确定的焊接接头局部区域的力学性能分布。拉伸试验和压头压痕试验的结果表明，焊接金属的机械性能甚至比母体金属更好。从金相研究中获得的数据表明，在热影响区中没有晶粒长大，这是由于所用焊接方法中的高冷却速率所致。根据详细阐述电子束焊接技术的结果并使用开发的技术，制造出符合VQC 1A类密封性要求的FWBS样机。