Heterogeneous connection of N6 nickel and Zr-2Hf annular lap joint by vacuum electron beam welding: Processing, microstructure characterization, and crack formation mechanism

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum Pub Date : 2025-04-17 DOI:10.1016/j.vacuum.2025.114348

Likuo Zhu , Guoqing Chen , Xinyan Teng , Lamei Zhang , Zhanhua Gan , Junhong Zhao , Chen Yang , Xuesong Leng

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Abstract

Crack formation poses a major challenge in the vacuum electron beam welding of N6/Zr-2Hf annular lap joint. To investigate the crack formation mechanism, a comparative study was conducted using both microstructural characterization and finite element simulations on tube/rod joint, with direct welding and offset welding methods. The results demonstrated that the key factors contributing to joint cracking include the presence of large size brittle Ni₅Zr phases, the unstable phase interface between γ-Ni/Ni₅Zr, and high residual stresses within the weld. Compared with the direct welding, Ni0.3-offset welding could effectively control the melting proportion of the base metals in the weld. The size of Ni₅Zr in the weld decreased, while the proportion of γ-Ni + Ni₅Zr ultra-fine eutectic phase increased, and the microstructure of the weld was optimized. When the beam was offset 0.3 mm to Ni side for welding, the peak stress of the weld decreased from 413 MPa to 320 MPa, which reduced the possibility of cracks in the weld. The tensile strength of the joint was increased from 82 MPa to 138 MPa, and the reliability of the joint was improved. This study provided some guidance for the subsequent welding of Zr/Ni dissimilar materials.

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真空电子束焊接N6镍与Zr-2Hf环形搭接接头的非均相连接：工艺、显微组织表征及裂纹形成机理

裂纹的形成是真空电子束焊接N6/Zr-2Hf环形搭接接头的主要难题。为探讨裂纹形成机理，采用直焊和偏焊两种焊接方法对管/杆接头进行了微观组织表征和有限元模拟对比研究。结果表明，大尺寸脆性Ni5Zr相的存在、γ-Ni/Ni5Zr相界面的不稳定以及焊缝内部的高残余应力是导致接头开裂的关键因素。与直焊相比，ni0.3偏移焊能有效控制焊缝中母材的熔化比例。焊缝中Ni5Zr的尺寸减小，γ-Ni + Ni5Zr超细共晶相的比例增加，焊缝组织得到优化。当梁向Ni侧偏移0.3 mm进行焊接时，焊缝峰值应力从413 MPa降低到320 MPa，降低了焊缝产生裂纹的可能性。接头抗拉强度由82 MPa提高到138 MPa，提高了接头的可靠性。该研究为Zr/Ni异种材料的后续焊接提供了一定的指导。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Vacuum 工程技术-材料科学：综合

CiteScore

6.80

自引率

17.50%

发文量

审稿时长

34 days

期刊介绍： Vacuum is an international rapid publications journal with a focus on short communication. All papers are peer-reviewed, with the review process for short communication geared towards very fast turnaround times. The journal also published full research papers, thematic issues and selected papers from leading conferences. A report in Vacuum should represent a major advance in an area that involves a controlled environment at pressures of one atmosphere or below. The scope of the journal includes: 1. Vacuum; original developments in vacuum pumping and instrumentation, vacuum measurement, vacuum gas dynamics, gas-surface interactions, surface treatment for UHV applications and low outgassing, vacuum melting, sintering, and vacuum metrology. Technology and solutions for large-scale facilities (e.g., particle accelerators and fusion devices). New instrumentation ( e.g., detectors and electron microscopes). 2. Plasma science; advances in PVD, CVD, plasma-assisted CVD, ion sources, deposition processes and analysis. 3. Surface science; surface engineering, surface chemistry, surface analysis, crystal growth, ion-surface interactions and etching, nanometer-scale processing, surface modification. 4. Materials science; novel functional or structural materials. Metals, ceramics, and polymers. Experiments, simulations, and modelling for understanding structure-property relationships. Thin films and coatings. Nanostructures and ion implantation.