【摘要】：6000系鋁合金一般沒有晶間腐蝕傾向性,但是合金中添加Cu、Mg與Si的質(zhì)量比不適當或者不合適的熱處理工藝都會降低6000系鋁合金的抗晶間腐蝕性能。本文以6082擠壓和鍛造鋁合金為研究材料,采用光學(xué)顯微鏡(OM)、掃描電鏡(SEM)及其自帶的能譜儀、背散射電子衍射儀(EBSD)、透射電鏡(TEM)、維氏硬度計等分析手段,采用晶間腐蝕實驗、維氏硬度測量等測試手段,分析研究了6082鋁合金的微觀組織演變規(guī)律和晶間腐蝕行為,研究結(jié)果表明:對于T6態(tài)6082鋁合金,隨著晶間腐蝕時間的延長,其最大腐蝕深度逐漸增加,當腐蝕時間超過5 h之后,縱向最大腐蝕深度增加幅度很小,但腐蝕在晶界處向晶內(nèi)擴展卻越來越嚴重,橫向腐蝕范圍和腐蝕程度逐漸增大。對于T6態(tài)6082鋁合金,均勻化溫度由510℃上升到530℃,均勻化時間由6 h延長到8 h,再結(jié)晶晶粒更加細小,成分組織更加均勻,其最大晶間腐蝕深度均減小,而且升高均勻化溫度比延長均勻化時間使最大晶間腐蝕深度降低的更多,說明均勻化處理溫度對合金抗晶間腐蝕性能的影響比處理時間更顯著。T6態(tài)6082鋁合金鍛件在晶間腐蝕之后發(fā)生中間區(qū)域重腐蝕和周圍區(qū)域輕腐蝕的現(xiàn)象,發(fā)生輕腐蝕的區(qū)域為單晶組織,是非常粗大的晶粒組織;發(fā)生重腐蝕的區(qū)域為多晶組織,該區(qū)域晶界上沒有發(fā)生溶質(zhì)原子的偏聚,也沒有析出,說明發(fā)生重腐蝕的原因與晶界析出無關(guān)。擠壓工藝、鍛造工藝造成的不均勻變形是導(dǎo)致鍛件固溶處理之后產(chǎn)生粗大晶粒組織的主要原因,不均勻變形會使合金晶界的界面能增大,晶核迅速長大,從而形成粗大的晶粒組織。本文實驗用的6082鋁合金晶界上沒有發(fā)生原子偏聚現(xiàn)象,沒有析出相,發(fā)生晶間腐蝕的原因與晶界析出無關(guān),晶間腐蝕是由α-Al基體與Mg2Si相以及α-Al基體與單質(zhì)Si之間的腐蝕電位差引起的點蝕導(dǎo)致其周圍基體逐漸溶解,擴展至晶界造成的,點蝕的過程包括點蝕的萌生和點蝕的擴展,點蝕首先萌生于在晶內(nèi)或晶界附近,結(jié)合電化學(xué)反應(yīng)對6082鋁合金點蝕的機理進行了分析研究。
[Abstract]:Generally, 6000 series aluminum alloys have no intergranular corrosion tendency, but the intergranular corrosion resistance of 6000 series aluminum alloys can be reduced when the mass ratio of CuPmg to Si is not suitable or the heat treatment process is not suitable. In this paper, 6082 extruded and forged aluminum alloy was used as the research material. The intergranular corrosion test was carried out by means of optical microscope, (OM), scanning electron microscope (SEM) and its own energy spectrometer, backscatter electron diffractometer, (EBSD), transmission electron microscope, (TEM), hardness tester, etc. The microstructure evolution and intergranular corrosion behavior of 6082 aluminum alloy were studied by Vickers hardness measurement. The results showed that for T6 6082 aluminum alloy, the intergranular corrosion time increased with the increase of intergranular corrosion time. The maximum corrosion depth increased gradually. When the corrosion time was more than 5 h, the longitudinal maximum corrosion depth increased very little, but the corrosion spread to the grain boundary more and more serious, and the transverse corrosion range and corrosion degree gradually increased. For T6 6082 aluminum alloy, the homogenization temperature is increased from 510 鈩，

本文編號：2154875