Effect of Welding Heat Input on the Microstructure and Impact Toughness of HAZ in 420 MPa-Grade Offshore Engineering Steel
In the present work, the effect of the welding heat input on the microstructure, martensite–austenite (M–A) constituents, and impact toughness of the coarse-grained heat-affected zone (CGHAZ) in offshore engineering steel with Ca deoxidation is studied. With the heat input increased from 50 to 100 k...
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Frontiers Media S.A.
2021-07-01
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| Series: | Frontiers in Materials |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmats.2021.694586/full |
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| author | Dekun Liu Jian Yang Yinhui Zhang Yunlong Qiu Guoguang Cheng Meiyi Yao Jianxin Dong |
| author_facet | Dekun Liu Jian Yang Yinhui Zhang Yunlong Qiu Guoguang Cheng Meiyi Yao Jianxin Dong |
| author_sort | Dekun Liu |
| collection | DOAJ |
| description | In the present work, the effect of the welding heat input on the microstructure, martensite–austenite (M–A) constituents, and impact toughness of the coarse-grained heat-affected zone (CGHAZ) in offshore engineering steel with Ca deoxidation is studied. With the heat input increased from 50 to 100 kJ/cm, the HAZ toughness decreased rapidly, while the measured microhardness decreases steadily. The grain sizes are increased from 52 to 132 μm, and the width of bainite lath increased from 0.4 to 2 μm. The area fraction of lath bainite (LB) decreased, while the area fraction of granular bainite (GB) increased. The average width of M–A constituents grows from 0.3 to 0.6 μm, and the average length grows from from 0.5 to 0.9 μm. Its area fraction is increased from 5.3 to 8.6% and then decreased to 6.1%, and its number density decreased from 0.7 to 0.2 μm−2. The morphologies of M–A constituents change from dot-like to slender and blocky, which are deleterious to impact toughness. The fracture mechanism changes from ductile to quasicleavage and cleavage as the heat input is increased. As the M–A constituents are always found as the cleavage initiation, they should be responsible for the decrease in HAZ toughness when the heat input is above 100 kJ/cm. |
| first_indexed | 2024-12-19T06:13:29Z |
| format | Article |
| id | doaj.art-4878067be592435391d34c019f22ff26 |
| institution | Directory Open Access Journal |
| issn | 2296-8016 |
| language | English |
| last_indexed | 2024-12-19T06:13:29Z |
| publishDate | 2021-07-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Materials |
| spelling | doaj.art-4878067be592435391d34c019f22ff262022-12-21T20:32:57ZengFrontiers Media S.A.Frontiers in Materials2296-80162021-07-01810.3389/fmats.2021.694586694586Effect of Welding Heat Input on the Microstructure and Impact Toughness of HAZ in 420 MPa-Grade Offshore Engineering SteelDekun Liu0Jian Yang1Yinhui Zhang2Yunlong Qiu3Guoguang Cheng4Meiyi Yao5Jianxin Dong6State Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, Shanghai, ChinaState Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, Shanghai, ChinaState Key Laboratory of Advanced Special Steel, School of Materials Science and Engineering, Shanghai University, Shanghai, ChinaZhongxing Energy Equipment Co., LTD, Haimen, ChinaState Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing, ChinaInstitute of Materials, Shanghai University, Shanghai, ChinaSchool of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, ChinaIn the present work, the effect of the welding heat input on the microstructure, martensite–austenite (M–A) constituents, and impact toughness of the coarse-grained heat-affected zone (CGHAZ) in offshore engineering steel with Ca deoxidation is studied. With the heat input increased from 50 to 100 kJ/cm, the HAZ toughness decreased rapidly, while the measured microhardness decreases steadily. The grain sizes are increased from 52 to 132 μm, and the width of bainite lath increased from 0.4 to 2 μm. The area fraction of lath bainite (LB) decreased, while the area fraction of granular bainite (GB) increased. The average width of M–A constituents grows from 0.3 to 0.6 μm, and the average length grows from from 0.5 to 0.9 μm. Its area fraction is increased from 5.3 to 8.6% and then decreased to 6.1%, and its number density decreased from 0.7 to 0.2 μm−2. The morphologies of M–A constituents change from dot-like to slender and blocky, which are deleterious to impact toughness. The fracture mechanism changes from ductile to quasicleavage and cleavage as the heat input is increased. As the M–A constituents are always found as the cleavage initiation, they should be responsible for the decrease in HAZ toughness when the heat input is above 100 kJ/cm.https://www.frontiersin.org/articles/10.3389/fmats.2021.694586/fulloffshore engineering steelcoarse-grained heat-affected zonebainiteM–A constituentsimpact toughnessCa deoxidation |
| spellingShingle | Dekun Liu Jian Yang Yinhui Zhang Yunlong Qiu Guoguang Cheng Meiyi Yao Jianxin Dong Effect of Welding Heat Input on the Microstructure and Impact Toughness of HAZ in 420 MPa-Grade Offshore Engineering Steel Frontiers in Materials offshore engineering steel coarse-grained heat-affected zone bainite M–A constituents impact toughness Ca deoxidation |
| title | Effect of Welding Heat Input on the Microstructure and Impact Toughness of HAZ in 420 MPa-Grade Offshore Engineering Steel |
| title_full | Effect of Welding Heat Input on the Microstructure and Impact Toughness of HAZ in 420 MPa-Grade Offshore Engineering Steel |
| title_fullStr | Effect of Welding Heat Input on the Microstructure and Impact Toughness of HAZ in 420 MPa-Grade Offshore Engineering Steel |
| title_full_unstemmed | Effect of Welding Heat Input on the Microstructure and Impact Toughness of HAZ in 420 MPa-Grade Offshore Engineering Steel |
| title_short | Effect of Welding Heat Input on the Microstructure and Impact Toughness of HAZ in 420 MPa-Grade Offshore Engineering Steel |
| title_sort | effect of welding heat input on the microstructure and impact toughness of haz in 420 mpa grade offshore engineering steel |
| topic | offshore engineering steel coarse-grained heat-affected zone bainite M–A constituents impact toughness Ca deoxidation |
| url | https://www.frontiersin.org/articles/10.3389/fmats.2021.694586/full |
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