Ag含量與熱處理對A201合金應力腐蝕性之影響; Effect of Ag content and Heat Treatments on Stress Corrosion Cracking of A201 Alloys

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Title:	Ag含量與熱處理對A201合金應力腐蝕性之影響;Effect of Ag content and Heat Treatments on Stress Corrosion Cracking of A201 Alloys
Authors:	葉明山;Ming-Shan Yeh
Contributors:	機械工程研究所
Keywords:	熱處理;Ω相;應力腐蝕性;Ag含量;A201合金;A201 alloy;Ag content;heat treatment;stress corrosion cracking;Ω phase
Date:	2003-06-20
Issue Date:	2009-09-21 11:41:56 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	A201(Al-Cu-Mg-Ag合金)為一高強度鋁合金，隨著Ag含量的增加，強化機制由θ’相逐漸轉為Ω相，且當施行不同熱處理時，晶界析出形態也會跟著改變。應力腐蝕破裂是A201鋁合金破裂的原因之一，其破壞性會隨著析出形態而改變，故本研究之目的在探討Ag含量與熱處理對A201鋁合金應力腐蝕性之影響。實驗設計四種銀含量試片，分別為0wt.%Ag、0.3 wt.%Ag、0.6 wt.%Ag與0.9 wt.%Ag含量的Al-4.6Cu-0.3Mg合金，施以不同的時效熱處理(T4、T6、RRA、T7)，探討在應力腐蝕環境下，各種時效熱處理條件對應力腐蝕敏感性的影響。並用光學顯微鏡(OM)、掃描式電子顯微鏡(SEM)、穿透式電子顯微鏡(TEM)、微差掃描熱分析儀(DSC)、導電度(%IACS)、硬度試驗、拉伸試驗(Tensile Test)與慢應變速率試驗(SSRT)等方法，探討微結構的變化與材料機械性質和抗應力腐蝕敏感性之關係。由實驗結果可知，在人工時效熱處理後，合金成份含銀0.6 wt.%時即能有效促使Ω相大量析出，進而大幅提升材料的機械強度。且隨著銀含量的增加，雖然能使Ω析出相增加且分布較為細密，卻也造成晶界處陽極溶解效應越趨嚴重；而T7熱處理晶界析出物粗大，無析出帶較寬，也使得抗應力腐蝕效果較T6、RRA佳。 A201(Al-Cu-Mg-Ag alloy)is a high strength aluminum alloy. With the increasing of Ag content,Ω phase will replace θ’ phase become the main strengthening phase. After different heat treatment, grain boundary precipitations will change. Stress corrosion cracking is one reason of A201 aluminum alloy happen to crack and the destructiveness will be different with the form of the precipitation. The effect of Ag content and heat treatment on stress corrosion cracking properties of A201 alloys were investigated. Using four different Ag content (0wt.%Ag、0.3wt.%Ag、0.6wt.%Ag and 0.9wt.%Ag) materials in the experiment. After different aging (T4、T6、RRA、T7), investigate the effect of heat treatment on the stress corrosion cracking of alloys, by using optical microscopy (OM), differential scanning calorimeter (DSC), electrical conductivity meter (%IACS), scanning electron microscopy (SEM), transmission electron microscopy (TEM). Analyzing the variation of microstructure of the alloys to compare with the variation of mechanical properties and stress corrosion cracking. Experimental results show that after artificial aging, alloy contains 0.6 wt.% Ag can promote Ω phase precipitate large, and improves the mechanical strength. With the increasing of Ag content, Ω phases precipitate more and finely, but anodic dissolution is serious at the grain boundaries. After T7 tempering, the grain boundary precipitations become coarse and the precipitate free zone becomes wide, then the stress corrosion cracking resistance is better than T6 and RRA tempering.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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