Analysis of Gas Metal Arc Welding Process and Microstructure Properties of EH40 Steel

XU Lindong; WU Lei; SUN Jianyu; WU Pengbo; XIN Guosong; CHEN Shaoxin; FANG Naiwen

doi:10.3969/j.issn.1674-6457.2026.08.009

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (8) : 99-108. DOI: 10.3969/j.issn.1674-6457.2026.08.009

Key Technologies for Precision Forming of High-end Energy and Aerospace Equipment Components

Analysis of Gas Metal Arc Welding Process and Microstructure Properties of EH40 Steel

XU Lindong¹, WU Lei², SUN Jianyu², WU Pengbo³, XIN Guosong⁴, CHEN Shaoxin³, FANG Naiwen^3,*

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Abstract

The work aims to realize the reasonable matching of strength and toughness of EH40 steel welded joints, analyze the evolution law of joint microstructure and its internal relationship with mechanical properties, and ensure the long-term safe and stable service of EH40 steel welded structure. In this paper, ER550 flux-cored wire was used to weld EH40 steel by gas metal arc welding. The effect of core process parameters such as welding current and voltage on weld formation was systematically studied, and the EH40 steel plate was welded after further optimizing the welding process parameters. The morphology, grain size, grain boundary and dimple morphology of each region of the joint were analyzed by means of metallographic microscope, scanning electron microscope and electron backscatter diffraction. With medium and low voltage of 26.5 V and 230 A welding current, the weld zone was composed of acicular ferrite+a small amount of proeutectoid ferrite+M-A island (MA). The overheated zone was composed of coarse lath bainite+retained austenite grain+acicular ferrite. The normalized zone was composed of ferrite (AF)+fine granular bainite (B). The microstructure of incomplete normalized zone was composed of fine equiaxed ferrite (PF). The average tensile strength of the welded joint was 598 MPa, the elongation after welding was 27%, and the fracture position was the base metal. Under the condition of -30 ℃, the impact absorption energy of the weld zone was 65 J, the impact absorption energy of the fusion zone was 97 J, and the impact absorption energy of the heat affected zone was 133 J. Through reasonable process optimization, the effective matching of strength and toughness of EH40 steel welded joints can be realized, which provides a theoretical basis and engineering reference for efficient and high-quality welding of EH40 steel.

Key words

EH40 steel / gas metal arc welding / welding process / mechanical property / microstructure

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XU Lindong, WU Lei, SUN Jianyu, WU Pengbo, XIN Guosong, CHEN Shaoxin, FANG Naiwen. Analysis of Gas Metal Arc Welding Process and Microstructure Properties of EH40 Steel[J]. Journal of Netshape Forming Engineering. 2026, 18(8): 99-108 https://doi.org/10.3969/j.issn.1674-6457.2026.08.009

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Funding

Taishan Industry Leading Talent Project Special Funds of China (2024001); Guangxi Key R&D Plan (AB25069254); Heilongjiang Provincial Natural Science Foundation (PL2025E073)