Fundamental research of corrosion fatigue at galvanized steel

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K18232
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Structural/Functional materials
• Research Institution: Tokyo University of Marine Science and Technology
• Principal Investigator: Morita Motoaki 東京海洋大学, 学術研究院, 助教 (30636626)
• Research Collaborator: MOTODA Shinichi 東京海洋大学, 学術研究院, 教授 (10190969) ; HASEGAWA Kayo 東京海洋大学, 大学院・海洋科学技術研究科・応用環境システム学専攻 ; UMEZAWA Osamu 横浜国立大学, 工学研究院, 教授 (20343171)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 腐食疲労 / 溶融亜鉛めっき鋼 / き裂起点部 / 亜鉛層 / 合金層

Outline of Final Research Achievements

In order to establish the design method of corrosion fatigue at hot-dip galvanized steel, the fatigue crack initiation and its propagation were analyzed. The microstructures due to the reduction of the fatigue strength and the corrosion fatigue strength were identified. Regardless of the presence or absence of corrosion, the microstructure due to decreasing fatigue strength in the low cycle region was the alloy layer in the galvanized layer. On the other hand, that in the high cycle region was the pure zinc layer in the galvanized layer. In the corrosive environment, the galvanized layer oxidized, and its hardness increased. From these results, the increase of fatigue strength under the condition of high humidity was caused by delaying the occurrence of cracks by formation of the oxide layer. It suggests that corrosion fatigue can be suppressed by controlling the microstructure of the corrosion product under a corrosive environment.

Free Research Field

機能・構造材料