Investigation of Microstructural Characterization and Tensile Deformation Mechanisms in Inconel 617 Welded Joints Produced by GTAW

TL;DR

This study examines the microstructure and strength of Inconel 617 welded joints made with GTAW, revealing how carbides and welding parameters affect their performance at high temperatures.

Contribution

The study provides new insights into the deformation mechanisms and strengthening effects in GTAW-welded Inconel 617 joints at elevated temperatures.

Findings

The weld zones show fine dendritic structures with uniformly distributed carbides, enhancing strength through precipitation and dislocation pinning.

Tensile strengths of 920 MPa at room temperature and 605.5 MPa at 750 °C were achieved, with joint efficiencies exceeding 117% and 121%.

Deformation at high temperatures is dominated by twinning due to reduced stacking-fault energy and carbide pinning effects.

Abstract

The microstructural evolution and tensile behavior of Inconel 617 welded joints produced by gas tungsten arc welding (GTAW) with ERNiCrCoMo-1 filler were systematically investigated. Detailed microstructural characterization revealed that Cr-rich M23C6 and Ti-rich MC carbides are the dominant precipitates, while Mo-rich M6C forms locally along grain boundaries after thermal exposure. The fusion and weld zones exhibit fine dendritic morphologies with uniformly distributed precipitates, resulting in significant strengthening through precipitation and dislocation–pinning mechanisms. Owing to the low heat input and compositional compatibility between the weld and base metals, the heat-affected zone remains extremely narrow and free of compositional transitions. The welded joint attains tensile strengths of 920 MPa at room temperature and 605.5 MPa at 750 °C, corresponding to joint efficiencies of 117% and 121%, respectively, with fracture consistently occurring in the base metal. Deformation analysis shows that plasticity at room temperature is governed by planar slip and dislocation entanglement, whereas deformation twinning predominates at elevated temperatures owing to the reduced stacking-fault energy and the pinning effect of M23C6 carbides. These results provide key insights into the deformation and strengthening mechanisms controlling the high-temperature performance of GTAW-welded Inconel 617 joints and offer guidance for their application in advanced nuclear and high-temperature energy systems.

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