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Article

A Comparative Study on the Performance and Microstructure of 304NG Stainless Steel in Underwater and Air Laser Welding

1
School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China
2
China Nuclear Power Operations Co., Ltd., Shenzhen 518124, China
3
Suzhou Nuclear Power Research Institute Co., Ltd., Suzhou 215004, China
*
Author to whom correspondence should be addressed.
Materials 2024, 17(15), 3854; https://doi.org/10.3390/ma17153854 (registering DOI)
Submission received: 21 June 2024 / Revised: 1 August 2024 / Accepted: 2 August 2024 / Published: 3 August 2024
(This article belongs to the Special Issue Advanced Welding in Alloys and Composites)

Abstract

In order to facilitate the application of underwater laser welding technology in in situ repairs of nuclear power plants, this study conducted comparative experiments between local dry underwater laser welding and laser welding in air on 304NG nitrogen-controlled stainless steel. The aim was to explore its microstructural evolution and mechanical properties in underwater environments. It was found that, near the fusion line of laser welding in air, columnar dendrites gradually evolved into cellular dendrites toward the weld center, eventually disappearing, resulting in a skeletal ferrite and serrated austenite structure. The underwater laser welding joints exhibited similar characteristics yet with more pronounced alternation between columnar and cellular dendrites. Additionally, the size of cellular dendrites decreased significantly, and needle-like ferrite was observed at the weld center. The hardness of underwater laser welded joints was slightly higher than that of in-air laser welded joints. Compared to laser welding in air, the strength of underwater laser welding joints increased from 443 MPa to 471 MPa, and the displacement increased from 2.95 mm to 3.45 mm, both types of welded joints exhibited a mixed mode fracture characterized by plasticity and brittleness.
Keywords: underwater laser welding; stainless steel; welding morphology; microstructure; mechanical properties underwater laser welding; stainless steel; welding morphology; microstructure; mechanical properties

Share and Cite

MDPI and ACS Style

Sun, J.; Yang, Y.; Wang, K.; Yin, S.; Li, Z.; Luo, Z. A Comparative Study on the Performance and Microstructure of 304NG Stainless Steel in Underwater and Air Laser Welding. Materials 2024, 17, 3854. https://doi.org/10.3390/ma17153854

AMA Style

Sun J, Yang Y, Wang K, Yin S, Li Z, Luo Z. A Comparative Study on the Performance and Microstructure of 304NG Stainless Steel in Underwater and Air Laser Welding. Materials. 2024; 17(15):3854. https://doi.org/10.3390/ma17153854

Chicago/Turabian Style

Sun, Jiaqi, Yue Yang, Kai Wang, Shaohua Yin, Zhen Li, and Zhen Luo. 2024. "A Comparative Study on the Performance and Microstructure of 304NG Stainless Steel in Underwater and Air Laser Welding" Materials 17, no. 15: 3854. https://doi.org/10.3390/ma17153854

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