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Effect of graphene on microstructure and mechanical properties of U-MIG-welded galvanized steel Guohong Ma1,*

, Chunxiang Wu1, Jia Ye2, Yinshui He3, and Xiaokang Yu1

1

School of Mechanical Engineering, Nanchang University, Nanchang 330031, China Applied Materials, Inc, P.O. Box 58039, Santa Clara, CA 95054-3299, USA 3 School of Environment and Chemical Engineering, Nanchang University, Nanchang 330031, China 2

Received: 4 June 2020

ABSTRACT

Accepted: 25 September 2020

In present study, Graphene nanoparticles (GNPs) are incorporated into the steel plate by dip coating technology, and the steel plate is welded by a composite welding process combined with an ultrasonic generator and a MIG welding machine (U-MIG). Joint samples of different contents of GNPs were obtained. After welding, the microstructure of the welded joint is characterized by OM, SEM, XRD, and RAMAN and compared with the bare sample. The results show that a certain amount of graphene nanoparticles can be evenly distributed in the center of the weld area, and the grains in the center of the weld are significantly refined. Using the nanoindentation technique to study the microhardness of the weld cross section, the hardness of the weld center has increased due to the addition of graphene; compared with the bare sample, the maximum enhancement rate of the GNPs coating sample is * 125.6%. The enhancement of the strength of the composite material is achieved by a variety of strengthening mechanisms, such as non-uniform nucleation, pinning effect, and hindering dislocation movement. This improvement in mechanical properties is attributed to the uniform dispersion of the hybrid particles and the refinement of the matrix grains and the good interface combination between the hybrid particles and the matrix.

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Springer Science+Business

Media, LLC, part of Springer Nature 2020

1 Introduction Metal-Inert Gas Welding (MIG) is currently the main welding technology used in the industry to manufacture various structural components owing to its advantages in terms of high quality, high productivity, and low fabrication cost, which is widely used in shipbuilding, chemical equipment, aerospace, and

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https://doi.org/10.1007/s10854-020-04553-7

other fields [1]. However, MIG welding still has some defects and limitations, such as insufficient penetration that may be caused by low permeability, and cracks and as-cast coarse structures will reduce the mechanical properties of the welded parts. According to previous studies, some nanoparticles can be used as welding fillers to improve the mechanical properties of welded parts [2].

J Mater Sci: Mater Electron

Base on the fact that graphene is a new type of twodimensional planar material with excellent physical and mechanical properties, such as theoretically defect-free single-layer graphene with a tensile strength of 130 GPa and an elastic modulus of 1.02 TPa [3, 4], at the same time, graphene is also an ideal material for many composite material reinforcemen