• CN: 11-2187/TH
  • ISSN: 0577-6686

Journal of Mechanical Engineering ›› 2025, Vol. 61 ›› Issue (8): 148-158.doi: 10.3901/JME.2025.08.148

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Effect of Heat Input on Microstructure, Mechanical Properties and Corrosion Behavior of Weathering Steel Weld Metal for High-speed Train Bogies

WANG Gaojian1,2, YE Yanhong1, KANG Dandan3, DENG Dean1   

  1. 1. College of Materials Science and Engineering, Chongqing University, Chongqing 400045;
    2. Sichuan Kexin Electromechanical Co., Ltd., Deyang 618400;
    3. College of Locomotive and Rolling Stock, Sichuan Railway College, Chengdu 611732
  • Received:2024-05-09 Revised:2024-11-07 Published:2025-05-10

Abstract: It is necessary to obtain weld metal with high toughness and high weather resistance for high-speed train bogies in the development of high-speed trains. However, the influence of welding heat input on the toughness and weather resistance of the weld metal has not been clarified. The effects of welding heat input on the microstructure, mechanical properties and corrosion behavior of Ti-containing weld metal with Ni-Cu alloy system, which was designed for high-speed train bogies, were investigated. The results show that with the increase of welding heat input and T8/5, the content of C in weld increases, the contents of Mn, Si, Ti and Ni elements decreases, the AF nucleation rate of inclusions in weld decreases, and the inclusions density increases first and then decreases. The above factors jointly result in the variation of the microstructure of weld metal to a certain extent. The content of AF in the welded zone reached the highest value when the heat input is 13.97 kJ/cm in the current study, while the grain size in the reheated zone becomes coarser with the increase of heat input. The increase of welding heat input leads to grain coarsening in the reheat zone becoming a key factor to negatively affect weld toughness. When welding heat input is higher, the weld is also affected by the loss of Ni content and the decrease of AF content, showing a further decrease in low-temperature impact toughness. However, Ti in the weld maintains a high AF content so that the high heat input weld still keeps a high toughness level of about 100 J of impact energy at -60 ℃. The initial corrosion rate of weld fluctuates slightly with the increase of heat input, and the corrosion rate of weld rust layer increases due to the influence of grain coarsening and loss of Ni and Ti content. This study revealed the mechanism and relationship between welding heat input and microstructure of weld metal, and provided technical support for the welding process optimization of high-speed train bogies under harsh service environment.

Key words: high speed train, weathering steel, microstructure, corrosion resistance, toughness, heat input

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