Mechanisms for mitigating liquid metal embrittlement via surface decarburization in Zn-coated advanced high-strength steels
Third-generation advanced high-strength steels (AHSS 3. Gen.) have been developed to improve lightweight design and safety in automotive applications. Their superior strength–ductility balance originates from retained austenite stabilized by Si. However, Si increases susceptibility to liquid metal e...
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Elsevier
2025-05-01
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| Series: | Journal of Materials Research and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785425009263 |
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| author | Hyungkwon Park Seong Hoon Kim Jin-Jong Lee Kyeong-Won Kim Chang-Hoon Lee Tejaswin Krishna Yeong-Do Park Min-Ho Jang Min-Seo Park Seong-Kyung Han Tae-Ho Lee |
| author_facet | Hyungkwon Park Seong Hoon Kim Jin-Jong Lee Kyeong-Won Kim Chang-Hoon Lee Tejaswin Krishna Yeong-Do Park Min-Ho Jang Min-Seo Park Seong-Kyung Han Tae-Ho Lee |
| author_sort | Hyungkwon Park |
| collection | DOAJ |
| description | Third-generation advanced high-strength steels (AHSS 3. Gen.) have been developed to improve lightweight design and safety in automotive applications. Their superior strength–ductility balance originates from retained austenite stabilized by Si. However, Si increases susceptibility to liquid metal embrittlement (LME) in Zn-coated steels during high-temperature processes such as resistance spot welding. Decarburization is proposed as a cost-effective LME mitigation strategy, though its effectiveness remains under debate. This study demonstrates that decarburization effectively mitigates LME severity, as revealed by interrupted welding tests and microstructural analysis. Crack reclassification based on morphology shows that non-decarburized steel exhibits fewer but more severe straight-shaped (S-type) cracks (72.17 %), whereas decarburized steel exhibits a greater number of shorter, network-shaped (N-type) cracks (79.87 %). This shift in crack behavior is closely linked to decarburization-induced microstructural changes. A higher fraction of high-angle grain boundaries (HAGBs) promotes Zn dispersion across multiple GBs, reducing localized Zn accumulation. Grain growth disrupts GB connectivity and deflects Zn propagation, while internal oxide formation weakens GB cohesion. Although these factors increase crack initiation, they collectively hinder crack propagation and shift the cracking mode from concentrated and damaging to more distributed and less detrimental. Consequently, decarburization modifies the surface microstructure and redistributes liquid Zn, effectively mitigating LME severity. These findings offer new insights into LME mitigation and underscore the potential of decarburization as a practical and scalable strategy for Zn-coated AHSS 3. Gen. |
| format | Article |
| id | doaj-art-cbf4e573a4ef4cfd9e4e5967cf355148 |
| institution | OA Journals |
| issn | 2238-7854 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | Elsevier |
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| series | Journal of Materials Research and Technology |
| spelling | doaj-art-cbf4e573a4ef4cfd9e4e5967cf3551482025-08-20T02:27:35ZengElsevierJournal of Materials Research and Technology2238-78542025-05-01364186419910.1016/j.jmrt.2025.04.103Mechanisms for mitigating liquid metal embrittlement via surface decarburization in Zn-coated advanced high-strength steelsHyungkwon Park0Seong Hoon Kim1Jin-Jong Lee2Kyeong-Won Kim3Chang-Hoon Lee4Tejaswin Krishna5Yeong-Do Park6Min-Ho Jang7Min-Seo Park8Seong-Kyung Han9Tae-Ho Lee10Extreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of Korea; Corresponding author.Extreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of KoreaDepartment of Advanced Materials Engineering, Dong-Eui University, Busan, Republic of KoreaDepartment of Advanced Materials Engineering, Dong-Eui University, Busan, Republic of KoreaResearch & Development (R&D) Center, Hyundai Steel Company, Dangjin, Republic of KoreaResearch & Development (R&D) Center, Hyundai Steel Company, Dangjin, Republic of KoreaResearch & Development (R&D) Center, Hyundai Steel Company, Dangjin, Republic of KoreaExtreme Materials Research Institute, Korea Institute of Materials Science, Changwon, Republic of Korea; Corresponding author.Third-generation advanced high-strength steels (AHSS 3. Gen.) have been developed to improve lightweight design and safety in automotive applications. Their superior strength–ductility balance originates from retained austenite stabilized by Si. However, Si increases susceptibility to liquid metal embrittlement (LME) in Zn-coated steels during high-temperature processes such as resistance spot welding. Decarburization is proposed as a cost-effective LME mitigation strategy, though its effectiveness remains under debate. This study demonstrates that decarburization effectively mitigates LME severity, as revealed by interrupted welding tests and microstructural analysis. Crack reclassification based on morphology shows that non-decarburized steel exhibits fewer but more severe straight-shaped (S-type) cracks (72.17 %), whereas decarburized steel exhibits a greater number of shorter, network-shaped (N-type) cracks (79.87 %). This shift in crack behavior is closely linked to decarburization-induced microstructural changes. A higher fraction of high-angle grain boundaries (HAGBs) promotes Zn dispersion across multiple GBs, reducing localized Zn accumulation. Grain growth disrupts GB connectivity and deflects Zn propagation, while internal oxide formation weakens GB cohesion. Although these factors increase crack initiation, they collectively hinder crack propagation and shift the cracking mode from concentrated and damaging to more distributed and less detrimental. Consequently, decarburization modifies the surface microstructure and redistributes liquid Zn, effectively mitigating LME severity. These findings offer new insights into LME mitigation and underscore the potential of decarburization as a practical and scalable strategy for Zn-coated AHSS 3. Gen.http://www.sciencedirect.com/science/article/pii/S2238785425009263Advanced high-strength steelLiquid metal embrittlementResistance spot weldingZn-coated steelMicrostructure |
| spellingShingle | Hyungkwon Park Seong Hoon Kim Jin-Jong Lee Kyeong-Won Kim Chang-Hoon Lee Tejaswin Krishna Yeong-Do Park Min-Ho Jang Min-Seo Park Seong-Kyung Han Tae-Ho Lee Mechanisms for mitigating liquid metal embrittlement via surface decarburization in Zn-coated advanced high-strength steels Journal of Materials Research and Technology Advanced high-strength steel Liquid metal embrittlement Resistance spot welding Zn-coated steel Microstructure |
| title | Mechanisms for mitigating liquid metal embrittlement via surface decarburization in Zn-coated advanced high-strength steels |
| title_full | Mechanisms for mitigating liquid metal embrittlement via surface decarburization in Zn-coated advanced high-strength steels |
| title_fullStr | Mechanisms for mitigating liquid metal embrittlement via surface decarburization in Zn-coated advanced high-strength steels |
| title_full_unstemmed | Mechanisms for mitigating liquid metal embrittlement via surface decarburization in Zn-coated advanced high-strength steels |
| title_short | Mechanisms for mitigating liquid metal embrittlement via surface decarburization in Zn-coated advanced high-strength steels |
| title_sort | mechanisms for mitigating liquid metal embrittlement via surface decarburization in zn coated advanced high strength steels |
| topic | Advanced high-strength steel Liquid metal embrittlement Resistance spot welding Zn-coated steel Microstructure |
| url | http://www.sciencedirect.com/science/article/pii/S2238785425009263 |
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