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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/9560

Title: 高強度螺絲氫脆及低週疲勞斷裂特性研究
Hydrogen Embrittlement and Low Cycle Fatigue Fracture of High Strength Steel Screw
Authors: 蔡履文
Contributors: NTOU:Institute of Materials Engineering
國立臺灣海洋大學:材料工程研究所
Date: 2009-07
Issue Date: 2011-06-28T07:09:32Z
Publisher: 行政院國家科學委員會
Abstract: 本研究為使用1022線材為製造高強度水泥螺絲線材,經表面滲碳,回火電鍍處理後,評估不同回火處理及螺絲幾何形狀,對於螺絲抗低週疲勞及氫脆性功效。實驗結果顯示,螺絲頭部下方幾何形狀、或降低應力集中效應,對提升螺絲抗低週疲勞斷裂有最大功效。另一方面於螺絲頭部所製作之安裝十字孔則會弱化其疲勞強度。定負載拉伸試驗及定扭力負載試驗顯示,電鍍後烘烤有助於降低螺絲頭部氫脆敏感性。在定負載條件下,螺絲經300℃或320℃回火處理,顯示有大略相同之抗氫脆能力。
In this work, AISI 1022 steel wire was used for making high strength concrete screws, which were carburized and tempered at distinct temperatures after shaping. Besides, some of the screws were subjected to baking at 200oC/3hr after electro-plating. Constant loading in salt water at 80oC was performed to evaluate the hydrogen embrittlement susceptibility of the screw. Moreover, bending fatigue tests were carried out to determine the fatigue strength of the screw under the criterion of resisting 105 cyclic loading. The results indicated that those screws tempered at lower temperature possessed higher strength and greater torque but lower bending angle than those tempered at higher temperatures. Modification of screw teeth geometry to lower the stress concentration in the threaded portion was found to effectively increase the screw torque and bending angle of the concrete screw. Under constant loading in tension, those modified screws showed similar resistance to hydrogen embrittlement in salt water, despite of tempering at 300 or 320 oC. Sustained bending tests under constant torque showed baking treatments had beneficial effects to reduce the susceptibility to hydrogen embrittlement. However, increasing the radius below the screw head or decreasing stress concentration effect was found to effectively reduce the likelihood of cracking/fracture of screw during sustained bending tests under constant torque. The results of bending fatigue tests showed the discontinuity below the screw head played the most important role in affecting the fatigue strength of concrete screws.
Relation: NSC98-2622-E019-004-CC3
URI: http://ntour.ntou.edu.tw/ir/handle/987654321/9560
Appears in Collections:[材料工程研究所] 研究計畫

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