爆炸焊接制备超导射频腔的铌-316L不锈钢过渡接头

Niobium-316L Stainless Steel Transition Joints for Superconducting Radiofrequency Cavities by Explosive Welding

摘要:

Nb/316L不锈钢过渡接头的研究可以为改进超导射频腔氦夹克的材料带来新的突破。本文利用爆炸焊接方式进行了铌和316L不锈钢的连接。为了观察复合材料的性能，对爆炸焊接和热处理后的复合材料进行了结合面微观结构和力学性能研究。微观结构研究表明结合面没有脆性金属间化合物形成且复合材料热处理后没有发现结合面有元素扩散。我们还对复合材料进行了室温和低温环境下的拉伸测试、剪切测试和弯曲测试。拉伸测试结果表明液氮温度下复合材料的强度高于室温环境,同时还观察到在液氮环境下复合材料有分层现象出现。最后我们进行了Nb-316LSS过渡接头的设计、加工和真空检漏，结果表明真空漏率满足工程要求，从而验证了Nb-316LSS复合材料用于SRF超导腔体氦夹克的可行性。

Abstract:

The study of the manufacture of niobium/316L stainless steel transition joints can lead to a new breakthrough in improving the material for the helium vessel of the superconducting radio frequency cavities. In this study, 316L stainless steel and niobium composite plates were fabricated by explosive welding technique. Microstructure and mechanical properties of the composite plates were investigated both immediately after explosive welding and after heat treatment processes. The investigation of microstructure demonstrated that no brittle intermetallic layer was formed and no diffusion phenomenon was observed after heat treatment processes. Mechanical tests including tensile tests, shear tests and bending tests were conducting both at room temperature and cryogenic temperature. At low temperature, the composite plates held higher strength than at the room temperature. In cryogenic tensile tests, we observed that the Niobium section of the composite plate broke in layers when the sample reached yielding strength. Beside the raw material, transition joints with Nb-SS adapters were designed and fabricated. The leak check showed the joints’ leak rates meet project requirements and indicated explosively bonded Nb-SS is viable way to fabricate stainless steel helium vessel for SRF cavities.