2021 Fiscal Year Final Research Report
Construction of material design principle for highly corrosion-resistant weld metal based on controlling heterophase interface characteristics of stainless steel
| Project/Area Number |
19H02461
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Basic Section 26040:Structural materials and functional materials-related
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| Research Institution | Osaka University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
門井 浩太 大阪大学, 接合科学研究所, 准教授 (40454029)
鴇田 駿 東北大学, 工学研究科, 助教 (60807668)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | ステンレス鋼 / 溶接金属 / 異相界面 / フェライト / オーステナイト / ミクロ組織 / 結晶方位関係 / 耐食性 |
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| Outline of Final Research Achievements |
Weld metals of austenitic stainless steel are expected to improve corrosion resistance by promoting the formation of lacy δ ferrite. By performing the second pass welding on the first pass weld metal whose growth direction of austenite is controlled, austenite in the first pass weld metal and austenite in the second pass weld metal grow in almost the same direction. And the frequency which δ ferrite in the second pass weld metal nucleates on austenite while satisfying with K-S relationship and grows while maintaining K-S relationship with austenite becomes high. It was clarified that this mechanism increases the formation ratio of lacy δ ferrite in the second pass weld metal. It was also confirmed that the weld metal produced by this process has improved corrosion resistance as compared with the conventional weld metal having a small amount of lacy δ ferrite.
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| Free Research Field |
材料組織学 溶接工学
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| Academic Significance and Societal Importance of the Research Achievements |
ステンレス鋼の溶接構造物では、溶接金属の耐食性確保が使用性能の点から極めて重要となる。ステンレス鋼溶接金属の耐食性の改善には、Cr、Mo等の増量や溶接後の熱処理が行われてきたが、コストアップや環境負荷低減の観点から、化学組成や熱処理実施の有無に依らない耐食性改善技術の確立が喫緊の課題である。
オーステナイト系ステンレス鋼では、溶接凝固割れ抑制の観点から、溶接金属中にδフェライトが含有されるが、δフェライトの形態により、耐食性が大きく異なる。したがって、耐食性が良好なレーシーδフェライトの生成を促進させることが、化学組成制御に依らないミクロ組織制御に基づく高耐食溶接金属実現に極めて有効である。
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