Effects of stabilized heat treatment on stress rupture properties of high Si-bearing austenitic stainless steel weld metal

The 15Cr-9Ni-Nb austenitic stainless steel weld metal with a Si content of 3.5 wt% was prepared via gas tungsten arc welding and then held at 900 °C for 3 h for the stabilized heat treatment (SHT). The stress rupture properties of the as-welded (AW) and SHT weld metals at 550 °C were evaluated via t...

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Bibliographic Details
Published in:The International journal of pressure vessels and piping 2024-10, Vol.211, p.105300, Article 105300
Main Authors: Chen, Yakui, Wu, Dong, Lu, Shanping
Format: Article
Language:English
Subjects:
Austenitic stainless steel weld metal
Stabilized heat treatment
Stress rupture properties
δ-ferrite
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Summary:The 15Cr-9Ni-Nb austenitic stainless steel weld metal with a Si content of 3.5 wt% was prepared via gas tungsten arc welding and then held at 900 °C for 3 h for the stabilized heat treatment (SHT). The stress rupture properties of the as-welded (AW) and SHT weld metals at 550 °C were evaluated via the Larson-Miller parameter. The microstructure evolution was discussed during the 550 °C stress rupture process. The coarse σ-phase and relatively fine G-phase formed on the δ-ferrite during aging at 550 °C. In the AW weld metal, the continuous δ-ferrite with a large amount of coarse σ-phase led to the formation and expansion of cracks during the stress rupture process, which accelerated the eventual rupture and damaged the stress rupture properties. The SHT decreased the δ-ferrite content and formed a large amount of nanoscale NbC precipitated in the matrix. The decreased δ-ferrite content avoided the rapid formation and expansion of cracks and the nanoscale NbC blocked the dislocation movement during the stress rupture process, which improved the stress rupture properties. •The microstructures of weld metals during different treatments were studied via optical microscope (OM), scanning electron microscopy (SEM), (transmission electron microscope) TEM, and scanning transmission electron microscopy (STEM).•The stress rupture properties of the weld metal at 550 °C were evaluated via the Larson-Miller parameter.•The effects of microstructure evolution and post-weld stabilized heat treatment on stress rupture properties at 550 °C were discussed.
ISSN:0308-0161
DOI:10.1016/j.ijpvp.2024.105300