Study of microstructural inhomogeneity and its effects on mechanical properties of multi-layer laser welded joint

Hybrid laser-arc welding is an emerging joining technology which has a promising prospect in thick plate manufacturing. In this paper, the thick plate butt joint of 16MnDR with 20 mm was successfully connected by using multi-layer laser welding technology. On this basis, the microstructural inhomoge...

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Bibliographic Details
Published in:International journal of advanced manufacturing technology 2018-02, Vol.94 (5-8), p.2163-2174
Main Authors: Zhang, Xiong, Mi, Gaoyang, Li, Shuo, Hu, Xiyuan, Wang, Chunming, Zhang, Yuelai
Format: Article
Language:English
Subjects:
Arc welding
Butt joints
CAE) and Design
Computer-Aided Engineering (CAD
Cooling rate
Ductile fracture
Engineering
Fracture toughness
Heat treating
Impact strength
Industrial and Production Engineering
Inhomogeneity
Laser beam welding
Lasers
Mechanical Engineering
Mechanical properties
Media Management
Microstructure
Multilayers
Original Article
Tensile strength
Thick plates
Welded joints
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Summary:Hybrid laser-arc welding is an emerging joining technology which has a promising prospect in thick plate manufacturing. In this paper, the thick plate butt joint of 16MnDR with 20 mm was successfully connected by using multi-layer laser welding technology. On this basis, the microstructural inhomogeneity and its influences on mechanical properties of the multi-layer welded joint were further investigated. The results indicated that microstructure of the multi-layer welded joint is inhomogeneous for two reasons: firstly, different heat inputs and cooling rates caused the microstructural inhomogeneity of different layers; secondly, different thermal cycles at different locations within inter-laminar zones led to disparate microstructure transformation and further intensified the microstructural inhomogeneity of the multi-layer welded joint. As a result, mechanical properties of the welded joint are obviously influenced by the microstructural inhomogeneity. From layer 1 to layer 4, the hardness distribution showed an overall downward trend and fluctuated obviously in inter-laminar zones. Besides, ductile fracture happened in all impact specimens, and the impact toughness decreased from layer 1 to layer 4 owing to the microstructural inhomogeneity and increasing microvoids. In addition, the uncleaned contamination between layers weakened the tensile strength of the welded joint. Thus, it is necessary for the multi-layer welding procedure to clear up former welds effectively before latter welding.
ISSN:0268-3768
1433-3015
DOI:10.1007/s00170-017-0944-3