The microstructure, the phase composition and the mechanical properties at 20°C and 870°C of a tubular welded joint from alloy HP40NbTi based on the Fe – 25% Cr – 35% Ni system are determined. The mechanism of fracture of the joint under short-term and long-term loading is studied. The role of the G-phase in nucleation and propagation of cracks in the structure of the alloy is revealed. An intermetallic G-phase is shown to form in the heat-affected zone under welding. It is shown that the G-phase lowers the long-term strength of the welded joint of alloy HP40NbTi as compared to the matrix metal.

中文翻译：

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G相对HP40NbTi难熔合金焊接接头断裂行为的影响

测定了基于 Fe – 25% Cr – 35% Ni 体系的 HP40NbTi 合金管状焊接接头在 20°C 和 870°C 下的显微组织、相组成和机械性能。研究了短期和长期载荷作用下关节的断裂机理。揭示了 G 相在合金结构中裂纹的形核和扩展中的作用。金属间化合物 G 相显示在焊接时的热影响区中形成。结果表明，与基体金属相比，G 相降低了合金 HP40NbTi 焊接接头的长期强度。