Inconel 825, a Ni–Fe–Cr alloy highly regarded for its exceptional corrosion resistance and high-temperature strength. This investigation studies the effect of heat input, precipitation, and micro segregation of Inconel 825 weldments and compares the effectiveness of two welding techniques: gas tungsten arc welding (GTAW) and electron beam welding (EBW). The findings indicate that increasing heat input generally enhances weldment quality by reducing the lack of penetration. However excessive heat input in GTAW leads to root cracking and solidification cracking; while EBW demonstrates better control over undercut and maintains consistent weld quality even at higher heat inputs. Both GTAW and EBW samples exhibit dendritic grain morphologies with distinctive grain boundaries. Precipitates, such as AlC and TiN, are observed in both processes, contributing to improved mechanical properties. While GTAW weldments show some degree of segregation for Mo, Cu, Ti, and Al, EBW weldments demonstrate negligible segregation for major alloying elements but micro-segregation of Ti and Al. EBW weldments additionally showcase higher average hardness, superior tensile strength, and ductility compared to GTAW weldments. This can be attributed to lower heat input, faster cooling rates, and a reduced rate of elemental segregation. Fractographic analysis reveals the presence of voids and micro-voids, indicating a ductile mode of failure for both GTAW and EBW samples. These void characteristics vary based on the heat input and microstructural features.

中文翻译：

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Inconel 825 焊件显微组织、析出和微观偏析的协同研究：GTAW 和 EBW 的比较研究

Inconel 825 是一种 Ni-Fe-Cr 合金，因其卓越的耐腐蚀性和高温强度而备受推崇。本研究研究了 Inconel 825 焊件的热输入、析出和微观偏析的影响，并比较了两种焊接技术的有效性：钨极气体保护焊 (GTAW) 和电子束焊 (EBW)。研究结果表明，增加热输入通常可以通过减少未焊透来提高焊件质量。然而，GTAW 的热输入过多会导致根部裂纹和凝固裂纹；而 EBW 则表现出更好的底切控制能力，即使在较高的热输入下也能保持一致的焊接质量。 GTAW 和 EBW 样品均表现出具有独特晶界的树枝状晶粒形态。在这两种工艺中都观察到了 AlC 和 TiN 等沉淀物，有助于提高机械性能。 GTAW 焊件显示出一定程度的 Mo、Cu、Ti 和 Al 偏析，而 EBW 焊件显示主要合金元素的偏析可忽略不计，但 Ti 和 Al 存在微偏析。与 GTAW 焊件相比，EBW 焊件还表现出更高的平均硬度、优异的拉伸强度和延展性。这可归因于较低的热输入、较快的冷却速率和元素偏析速率的降低。断口分析揭示了孔隙和微孔隙的存在，表明 GTAW 和 EBW 样品均存在延性失效模式。这些空隙特征根据热输入和微观结构特征而变化。