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Journal of Shanghai Jiaotong University(Science) >

2024 , Vol. 29 >Issue 2: 349 - 360

DOI: https://doi.org/10.1007/s12204-023-2638-3

Materials Science and Engineering

Toughening Mechanism of Large Heat Input Weld Metal for Marine Engineering Extra-Thick Plate

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  • (1. School of Materials Science and Engineering, Tianjin University, Tianjin 300350, China; 2. Tianjin Key Laboratory of Advanced Joining Technology, Tianjin 300350, China; 3. Penglai Jutao Offshore Engineering Heavy Industry Co. Ltd., Yantai 265600, Shandong, China)

Received date: 2022-11-13

  Accepted date: 2023-01-15

  Online published: 2024-03-28

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Abstract

In order to study the latest designed large heat input welding material of marine engineering extrathick plate, EH36 steel was joined by using twin-wire submerged arc welding with heat inputs of 85, 100 and 115 kJ/cm separately. Meanwhile, the microstructure and mechanical properties were evaluated to explore the toughening mechanism of weld metal. Results show that a lot of active inclusions are obtained in the weld metal due to the design idea of low carbon and oxide metallurgy, which contributes to the generation of numerous fine and interlocking acicular ferrite. The acicular ferrite volume ratio of weld metal exceeds 60%. Moreover, the impact energy at −40 ◦C surpasses 115 J and the crack tip opening displacement value at −10 ◦C is more than 0.2 mm under three heat inputs owing to the role of acicular ferrite, of which 85 kJ/cm is the best. The martensiteaustenite constituents are minor in size and the microstructure of the weld metal in reheated zone is dominated by small massive equiaxed ferrite, without impairing the toughness. As the heat input increases, the content of acicular ferrite drops and then rises; the impact toughness and fracture toughness first worsen consequently and then stabilize on account of the dramatic expansion of the proeutectoid ferrite size.

Key words： large heat input, extra-thick plate, weld metal, acicular ferrite, toughness

Cite this article

LENG Junjie1 (冷俊杰), DI Xinjie,2*1 (邸新杰), LI Chengning1,2 (利成宁), CHENG Shanghua3 (程尚华) . Toughening Mechanism of Large Heat Input Weld Metal for Marine Engineering Extra-Thick Plate[J]. Journal of Shanghai Jiaotong University(Science), 2024 , 29(2) : 349 -360 . DOI: 10.1007/s12204-023-2638-3

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