ハスヌマ　ショウタ   HASUNUMA Shota   蓮沼　将太    所属   青山学院大学  理工学部 機械創造工学科    職種   准教授
言語種別	日本語
発行・発表の年月	2011/03
形態種別	学術雑誌
査読	査読あり
標題	低合金鋼SFVQ1Aの低サイクル疲労における微小き裂進展に及ぼす予ひずみ履歴の影響
執筆形態	共同
掲載誌名	材料(日本材料学会)
巻・号・頁	210-216頁
著者・共著者	蓮沼将太，宮田陽平, 坂上賢一, 小川武史
概要	Low cycle fatigue tests were performed for a low alloy steel, JIS SFVQ1A, used for pressure vessels of nuclear power plants. The effect of pre-strain history on the small crack initiation and growth was investigated in detail using cellulose acetate replicas. Under the tests in which the total strain range, Δε, is constant, surface crack length, 2c, was smaller for the tests with larger Δε due to the different numbers of small crack initiation and coalescence. The pre-strain histories were applied at Δε of 8 or 16% with its fatigue usage factor, UF, of less than 0.2, followed by fatigue loading at Δε = 2% until fracture. In these tests, the relationships between 2c and UF agreed with each other unless crack coalescence occurred. The scatter in fatigue life was attributed to the coalescences of small cracks. Fracture mechanics approach was applied to predict the fatigue lives and to characterize the growth behavior of small fatigue cracks.