In this study, the effect of Nb content and aging temperature on the weld of Inconel 690 was investigated by the behavior of \({\text{M}}_{23} {\text{C}}_{6}\). After changing the Nb content of FM-52 to 0.65 wt%, 1.48 wt%, 2.45 wt%, and 3.46 wt%, shielded metal arc welding was conducted under constrained conditions to reduce the thermal deformation. As a result of measuring the hardness after aging treatment, the hardness increased with the Nb content, and it was determined that the transgranular and intergranular precipitation effect of MC on the increase in hardness was greater than that of \({\text{M}}_{23} {\text{C}}_{6}\), which mainly precipitated at the migrated grain boundary (MGB) compared to MC. Optical Microscope analysis showed that the MGB changed from a straight type to a vermicular type as the Nb content increased. As a result of SEM/EDS and EBSD analysis, most of the carbide (\({\text{M}}_{23} {\text{C}}_{6}\)) was observed in specimen A with a low Nb content and decreased with an increase in the aging temperature, and the fraction of \({\text{M}}_{23} {\text{C}}_{6}\) decreased with an increase in the Nb content. Micro-voids were generated by a large amount of \({\text{M}}_{23} {\text{C}}_{6}\) at an aging temperature of 600–800 °C in the A and B specimens with a relatively low Nb content. The pitting resistance was improved due to the amount of Cr-rich \({\text{M}}_{23} {\text{C}}_{6}\) decreased as the Nb content increased. However, no decrease in corrosion resistance was observed owing to the micro-voids produced near Cr-rich \({\text{M}}_{23} {\text{C}}_{6}\).

Graphic Abstract

中文翻译：

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根据 Nb 含量和时效温度的 Inconel 690 碳化物行为和微孔洞

本研究通过\({\text{M}}_{23} {\text{C}}_{6}\) . 在将 FM-52 的 Nb 含量改为 0.65 wt%、1.48 wt%、2.45 wt% 和 3.46 wt% 后，在约束条件下进行保护金属电弧焊以减少热变形。时效处理后硬度测定结果表明，随着Nb含量的增加，硬度增加，确定MC对硬度增加的穿晶和晶间析出作用大于\({\text{M} }_{23} {\text{C}}_{6}\)，与 MC 相比，主要在迁移的晶界 (MGB) 处析出。光学显微镜分析表明，随着 Nb 含量的增加，MGB 从直线型变为蠕虫型。作为 SEM/EDS 和 EBSD 分析的结果，在试样 A 中观察到大部分碳化物（\({\text{M}}}_{23} {\text{C}}_{6}\)） Nb 含量低，随着时效温度的升高而降低，\({\text{M}}_{23} {\text{C}}_{6}\)的分数随着 Nb 的增加而降低内容。微孔是由大量的\({\text{M}}_{23} {\text{C}}_{6}\)在 600-800 °C 的老化温度下在 A 和Nb 含量相对较低的 B 试样。由于富Cr的量，耐点蚀性得到改善\({\text{M}}_{23} {\text{C}}_{6}\)随着 Nb 含量的增加而减少。然而，由于在富铬\({\text{M}}_{23} {\text{C}}_{6}\)附近产生的微孔洞，没有观察到耐腐蚀性能下降。

图形摘要