The methods of optical and electron microscopy and x-ray spectrum microanalysis are used to study the microstructure and phase composition of a tubular welded joint from alloy HP40NbTi based on the Fe – 25Cr – 35Ni system. Short-term and long-term mechanical properties of the alloy are determined. The joint is characterized by structural inhomogeneity and formation of silicon segregations and G-phase in the structure of the metal in the heat-affected zone. It is shown that the special features of the structure of the welded joint from alloy HP40NbTi lower considerably its mechanical properties at the operating temperatures of pyrolysis facilities.

中文翻译：

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耐火合金HP40NbTi管状焊接接头的结构，相组成和力学性能分析

利用光学和电子显微镜以及X射线光谱显微分析方法，研究了基于Fe – 25Cr – 35Ni体系的HP40NbTi合金管状焊接接头的组织和相组成。确定合金的短期和长期力学性能。接头的特征是结构不均匀，并在热影响区的金属结构中形成硅偏析和G相。结果表明，HP40NbTi合金焊接接头的结构特点在热解设备的工作温度下会大大降低其机械性能。