Microstructure and impact toughness at different positions of weld metal in thick plate of 2.25Cr-1Mo-0.25V steel
Journal of Mechanical StrengthVol. 48, Issue 7, Pages: 102-109(2026)
作者机构:
1.四川大西洋焊接材料股份有限公司,自贡 643000
2.兰州理工大学 材料科学与工程学院,兰州 730050
作者简介:
CAO Rui, E-mail: caorui@lut.edu.cn
基金信息:
Gansu Province Key R&D Plan(23YFGA0057);Top Leading Talents Project of Gansu Province;Central Leading Local Science and Technology Development Special Project(24ZYQA054);National Natural Science Foundation of China(52175325);Major Scientific and Technological Projects of Gansu Province(24ZD13GA018;23ZDGA010;22ZD6GA008)
Xu Xiaolong,Dou Guishan,Yao Jun,et al. Microstructure and impact toughness at different positions of weld metal in thick plate of 2.25Cr-1Mo-0.25V steel[J]. Journal of Mechanical Strength,2026,48(7):102-109.
Xu Xiaolong,Dou Guishan,Yao Jun,et al. Microstructure and impact toughness at different positions of weld metal in thick plate of 2.25Cr-1Mo-0.25V steel[J]. Journal of Mechanical Strength,2026,48(7):102-109.DOI: 10.16579/j.issn.1001.9669.2026.07.012.
Microstructure and impact toughness at different positions of weld metal in thick plate of 2.25Cr-1Mo-0.25V steel
Low impact energy occurring in multi-layer and multi-pass weld metal of 2.25Cr-1Mo-0.25V steel is a critical concern in the petrochemical industry. Investigating the microstructure in different regions of thick-plate multi-layer multi-pass weld metal and its influence on impact toughness is of great significance for improving the safe service performance of welded structures.
Methods
2
Firstly
optical microscopy and scanning electron microscopy were adopted to characterize the microstructure at different positions of the weld metal. Afterwards
Charpy impact tests and microhardness tests were carried out to examine the stability of mechanical properties of the weld metal.
Results
2
The results reveal that the microstructure of weld metal at all tested positions consists of ferrite
carbides
Martensite-Austenite constituents and non-metallic inclusions. Nevertheless
the minimum impact energy of 31 J is obtained at the middle position (1/2 thickness from the top surface)
and the microhardness at this position is lower than that at the position 1/4 thickness from the top surface. The degradation of impact toughness mainly originates from the microstructural inhomogeneity in this region
manifested as coarse grains and large-sized non-metallic inclusions. These factors collectively reduce the plastic deformation capacity and degree of deformation of local areas
weakening the resistance to crack nucleation and propagation. Cleavage cracks tend to initiate at an early stage and propagate rapidly
resulting in a short steady-state propagation zone of ductile cracks. Consequently
the combined effect of coarse grains and large non-metallic inclusions drastically deteriorates the impact toughness of the local middle region of the weld.
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