The temperature effect on deformation behavior, microstructural evolution and fracture mechanism of Inconel 625 superalloy sheet were systematically investigated in a wide temperature range from room temperature (RT) to 950 °C. Tensile temperature was varied in increments of 50 °C after reaching 500 °C. Obvious serrations occurred at the medium temperature range and evolved in the sequence of B→B+C→C with increasing temperature. Microscopic observations from transmission electron microscopy (TEM) indicated that the interaction between C14-Ni₂Nb Laves phases and mobile dislocations was found to be responsible for the type B serration, and the type C serration was associated with nucleation and growth of deformation twins. Recrystallized grains were observed above 850 °C, and results from electron backscattered diffraction and TEM showed that both continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) take place, while CDRX was the secondary nucleation mechanism. The stress concentration caused by Nb-rich phases was responsible for crack nucleation at tensile temperatures below 650 °C. The combined action of slip bands impingement on grain boundaries and stress concentration caused by Nb-rich phases led to crack initiation at the tensile temperature of 750 °C and 850 °C. Void nucleation at triple junctions of grain boundaries resulted from grain boundary sliding should be responsible for the ductile fracture at 950 °C.

Data availability

All data are available from the corresponding author on reasonable request.

中文翻译：

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Inconel 625高温合金的变形行为，微观组织演变和断裂机理的温度依赖性

在室温（RT）至950°C的较宽温度范围内，系统地研究了温度对Inconel 625高温合金板的变形行为，微观组织演变和断裂机理的影响。达到500°C后，拉伸温度以50°C的增量变化。在中等温度范围内出现明显的锯齿，并随温度的升高按B→B + C→C的顺序演化。透射电子显微镜（TEM）的显微镜观察表明，C14-Ni ₂之间的相互作用发现Nb Laves相和移动位错是造成B型锯齿的原因，而C型锯齿与形变孪晶的形核和生长有关。在850°C以上观察到重结晶晶粒，电子反向散射衍射和TEM结果表明，连续动态重结晶（CDRX）和不连续动态重结晶（DDRX）均发生，而CDRX是次生成核机制。在650°C以下的拉伸温度下，富Nb相引起的应力集中是裂纹成核的原因。滑移带撞击晶界和富Nb相引起的应力集中的综合作用导致在750°C和850°C的拉伸温度下产生裂纹。

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