This study examines the feasibility of using pressure resistance welding to create solid-state bonding between oxide dispersion strengthened MA-957 alloy cladding tubes and ferritic-martensitic HT-9 alloy end-plugs. The joint configuration is prototypic of the closure welding process used in the fabrication of reactor fuel pins. Optimized joining parameters were found to create sound metallurgical bonding at the joint interface. Using electron backscatter diffraction, a characteristic microstructural gradient is noted across the weld joint with dynamic recrystallization occurring at the thermomechanically affected zone (TMAZ) of the MA-957 whereas martensite formation occurs in both the TMAZ and heat-affected zone (HAZ) of the HT-9. A decrease in dislocation density coupled with slight agglomeration of the nano-sized oxide particles in the TMAZ of the MA-957 likely decreased the hardness whereas martensite strengthening in the HT-9 coupled with some degree of grain refinement pushed the microhardness to more than 500 HV. In order to level the hardness gradient, a post-weld heat treatment was applied on the joint creating a tempering effect in the harder HT-9 side and decreasing the hardness gradient. Further studies will be needed to understand all the performance characteristics of this type of joint.

这项研究检验了使用耐压焊接在氧化物弥散强化的MA-957合金熔覆管和铁素体-马氏体HT-9合金端塞之间建立固态结合的可行性。接头配置是反应堆燃料销制造中使用的封闭焊接工艺的原型。发现优化的连接参数可在连接界面处产生良好的冶金结合。使用电子背散射衍射，在焊缝上观察到特征性的微结构梯度，在MA-957的热机械影响区（TMAZ）发生动态再结晶，而马氏体在TMAZ和热影响区（HAZ）均发生。 HT-9。位错密度的降低以及MA-957的TMAZ中纳米尺寸氧化物颗粒的轻微团聚可能会降低硬度，而HT-9中的马氏体强化以及一定程度的晶粒细化将显微硬度提高到500以上高压 为了使硬度梯度均匀，对接头进行了焊后热处理，从而在较硬的HT-9侧产生了回火效果，并降低了硬度梯度。需要进一步的研究来了解这种类型的关节的所有性能特征。在接头上进行了焊后热处理，从而在较硬的HT-9侧产生了回火效果，并降低了硬度梯度。需要进一步的研究来了解这种类型的关节的所有性能特征。在接头上进行了焊后热处理，从而在较硬的HT-9侧产生了回火效果，并降低了硬度梯度。需要进一步的研究来了解这种类型的关节的所有性能特征。