SN490B鋼銲件之巨觀力學特性與微觀結構研究 = A Study on...
國立高雄大學土木與環境工程學系碩士班

 

  • SN490B鋼銲件之巨觀力學特性與微觀結構研究 = A Study on Macro-mechanism and Microstructure of SN490B Steel Welds
  • 紀錄類型: 書目-語言資料,印刷品 : 單行本
    並列題名: A Study on Macro-mechanism and Microstructure of SN490B Steel Welds
    作者: 林志和,
    其他團體作者: 國立高雄大學
    出版地: [高雄市]
    出版者: 撰者;
    出版年: 2010[民99]
    面頁冊數: 192面圖,表 : 30公分;
    標題: SN490B鋼
    標題: SN490B Steel
    電子資源: http://handle.ncl.edu.tw/11296/ndltd/14986118732151473127
    摘要註: 本研究從巨觀力學試驗與微觀金相組織,探討銲接面上的銹蝕對銲件之可能影響。本研究模擬施工現場,使用遮護金屬電弧銲接(Shielded Metal Arc Welding, SMAW)與包藥銲線電弧銲接(Flux Cored Arc Welding, FCAW)兩種銲接方法,來對25mm的SN490B鋼板進行銲接。鋼板接合方式有十字接與對接之兩種。銲接面條件分別為磨光接面、銹蝕A級、銹蝕B級、銹蝕C級、銹蝕D級、貼膠帶以及塗可銲漆。本研究之主要結果如下:(1) 銲接面上的銹蝕對銲件的降伏強度、抗拉強度、伸長率、斷面縮率、硬度值以及衝擊值,沒有明顯的影響。但銲接面有銹蝕的拉伸試片在母材與銲道交界處有裂縫。 (2) 銲接面上的銹蝕不會對銲道與熱影響區之金相組織型態做改變,但銹蝕接面的孔洞較多。這也證實了接面上的銹蝕在銲接時經高溫溶解成氣體不會完全逸散,因此會殘留增加銲道內孔隙。(3) 偏析線對銲件的降伏強度與抗拉強度沒有明顯的影響,但會減少銲件的伸長率與斷面縮率,並使破裂面完全呈脆性。從金相組織也可看出,偏析線是由一排或數個孔洞連續排列所組成,故拉伸試驗銲件容易斷在偏析線上。由(1)與(2)可知,銲接面上有銹蝕的銲件在母材與銲道交界處易有裂縫,且銹蝕在銲接時經高溫溶解成氣體、會增加銲道內孔隙。建議後續研究針對此定性結果,進一步模擬地震作用來對銲接面上有銹蝕的銲件進行反覆載重試驗,以更瞭解銲接面上的銹蝕對銲件之影響。 To investigate the effects of welding surface rust, this study carries out a series of mechanic testing on SN490B steel welds, comparing the metallurgical structure under microscope. The T-joints and butt joints welds were made of 25-mm steel plates. Two kinds of welding methods were used, including shielded metal arc welding (SMAW) and flux cored arc welding (FCAW). These two methods are also the most popular ones at construction sites. The welding surfaces were polished, covered with rust of Grade A, B, C and D, struck with tape, and coated with a layer of weldable paint, respectively. From the above study, the following conclusion can be drawn. (1)Welding surface rust cannot cause severe impact on yield and tensile strength, elongation, cross-section shrinkage, hardness and toughness of steel welds. However, the rust may cause the initial cracks between weld and steel metal. (2)Welding surface rust almost cannot change the pattern or metallurgical structure of weld, heat-affected zone and steel metal. But the rust may increase porosity in weld and heat-affected zone. It suggests that welding cannot cause surface rust to escape completely, and part of the rust finally makes corrosion holes. (3)Segregation lines may not cause severe impact on the yield strength and tensile strength of steel welds, but can significantly reduce the elongation and cross-section shrinkage rate, causing brittle fracture. It can be seen under microscope that segregation lines are a row of holes. That explains why the T-joints may fail for the segregation lines in column plates. (4)From (1) and (2), it can be suggested that welding surface rust may increase porosity in weld and heat-affected zone, causing the initial cracks between weld and steel metal. To further investigate the effects, cyclic tests will be undertaken at the next phase of this research.
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310001952616 博碩士論文區(二樓) 不外借資料 學位論文 TH 008M/0019 541606 4442 2010 一般使用(Normal) 在架 0
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