本文選題：Al-Mn系合金　切入點(diǎn)：微合金化　出處：《東南大學(xué)》2017年碩士論文

【摘要】：復(fù)合釬焊式熱交換器的生產(chǎn)工藝和工作環(huán)境要求熱交換器用鋁合金具有一定的耐高溫性能,本文在典型Al-Mnu系3003合金的基礎(chǔ)上添加了不同的合金元素,研究微合金化和熱處理工藝對(duì)熱交換器用芯材Al-Mn系合金再結(jié)晶過程及組織的影響,結(jié)合合金微觀組織的有效控制和蠕變機(jī)理,研究了合金元素對(duì)Al-Mn系合金高溫力學(xué)性能,尤其是高溫蠕變性能的影響。本文首先研究了合金元素對(duì)Al-Mn系合金退火組織的影響。結(jié)果表明:Mg、Cu、Ce、La可細(xì)化合金退火晶粒,Mg和Ni或Mg和Zr聯(lián)合添加促進(jìn)了退火晶粒的長條狀程度;Mg促進(jìn)了AlMnSi相的析出,Ni增加了化合物的種類和數(shù)量(AlMnFeSiNi相、AlMnSiNi相),Ce/La的加入形成了較多的AlRESi稀土化合物。此外,Al-Mn、Al-Mn-0.3Mg、Al-Mn-0.3Mg-0.2Ni和Al-Mn-0.3Mg-0.2Zr合金退火過程中沉淀相析出與再結(jié)晶相互作用的臨界溫度Tc分別為396℃、405℃、430℃和433℃;冷軋Al-Mn合金在600℃(高于Tc)退火,再結(jié)晶先于析出,得到細(xì)小等軸晶;而先經(jīng)350℃(低于Tc)退火處理,析出先于再結(jié)晶,獲得沿軋制方向分布的長條狀晶粒,因率先析出的AlMnSi等相尺寸較小,再在600℃下退火仍具有抑制晶界法向移動(dòng)的作用,最終保持有利于蠕變性能的長條狀組織。對(duì)Al-Mn系合金進(jìn)行了高溫拉伸性能和蠕變性能測(cè)試。結(jié)果表明:單獨(dú)添加0.3%Mg對(duì)Al-Mn系合金高溫性能的改善效果好于單獨(dú)添加0.1%Ni;所有合金中Al-Mn-0.3Mg-0.2Ni(S4)合金具有最佳的高溫性能,200℃和250℃下高溫抗拉強(qiáng)度分別達(dá)到131MPa和lO1MPa(提高了90%和98%),200℃/40MPa條件下穩(wěn)態(tài)蠕變速率ε=5.71×10-9s-1比Al-Mn合金(ε=8.80×10-8s-8s-1)低一個(gè)數(shù)量級(jí),而250℃/40MPa條件下穩(wěn)態(tài)蠕變速率從5.07×l06s-l減至3.93×10-8s-1降低了兩個(gè)數(shù)量級(jí);Al-Mn-0.3Mg-0.2Zr合金在250℃/40MPa條件下穩(wěn)態(tài)蠕變速率ε=5.21×10-8s-1,對(duì)Al-Mn合金蠕變性能的改善僅次于S4合金。Mg和Ce/La聯(lián)合添加時(shí),合金的高溫強(qiáng)度、抗蠕變性能進(jìn)一步提高,但由于晶粒組織發(fā)生細(xì)化,改善效果并不明顯。研究了Al-Mn系合金在175～250℃、外加應(yīng)力25～50MPa條件下的蠕變行為,運(yùn)用冪指數(shù)方程建立了 Al-Mn系合金穩(wěn)態(tài)蠕變本構(gòu)方程。結(jié)果表明:Al-Mn合金在175℃下蠕變應(yīng)力指數(shù)n=3.4,蠕變過程受位錯(cuò)粘滯性滑移控制;在200～250℃下,蠕變受位錯(cuò)攀移控制(n=5.9～8.3);合金元素Mg或Mg和Ni/Zr的聯(lián)合添加使Al-Mn合金在200～225℃下,蠕變?nèi)允芪诲e(cuò)粘滯性滑移控制(n=2.9～3.9),而位錯(cuò)粘滯性滑移速率低于位錯(cuò)攀移速率,抗蠕變性能提高。此外,蠕變前后沉淀相TEM結(jié)果表明,Al-Mn系合金的高溫性能與沉淀相析出量和種類有關(guān),析出量及種類越多、結(jié)構(gòu)越復(fù)雜,對(duì)位錯(cuò)運(yùn)動(dòng)(粘滯性滑移、攀移)和晶界滑動(dòng)的阻礙作用越大,相應(yīng)合金的高溫性能越好。
[Abstract]:The production process and working environment of composite brazing heat exchanger require aluminum alloy for heat exchanger to have certain high temperature resistance. Different alloying elements are added to the typical Al-Mnu 3003 alloy in this paper. The effect of microalloying and heat treatment on recrystallization process and microstructure of Al-Mn series alloy for heat exchanger was studied. Combined with the effective control of microstructure and creep mechanism, the high temperature mechanical properties of Al-Mn series alloy were studied. In this paper, the effect of alloying elements on the annealing microstructure of Al-Mn alloys is studied. The results show that the grain size of the alloy can be refined by the addition of mg and Ni or the addition of mg and Zr to the annealed alloy. The results show that the addition of mg and Ni or mg and Zr can promote the annealed grain. In addition, the addition of AlMnFeSiNi phase and AlMnFeSiNi phase can form more AlRESi rare earth compounds. In addition, the precipitated phase and recrystallized phase of Al-MnFeSiNi phase and Al-Mn-0.3Mg-0.2Zr alloy are precipitated and recrystallized in the annealing of Al-MnMn-0.3Mgn-0.3Mg-0.2Ni and Al-Mn-0.3Mg-0.2Zr alloy. The critical temperature of interaction is 396 鈩，

本文編號(hào)：1670568