(中南大學(xué) 材料科學(xué)與工程學(xué)院， 長沙 410083)
摘 要: 采用光學(xué)顯微鏡、 透射電子衍射和掃描電子衍射顯微分析技術(shù)， 結(jié)合力學(xué)性能檢測和電導(dǎo)率測定的方法， 研究雙級固溶溫度和時(shí)間對7A55鋁合金板材力學(xué)性能的影響。 結(jié)果表明： 最佳雙級固溶制度為450 ℃, 90 min+485 ℃, 40 min。 采用該固溶制度經(jīng)120 ℃, 24 h時(shí)效后， 板材的拉伸力學(xué)性能達(dá)到σb＝648.4 MPa, σ0.2＝629.6 MPa及δ＝11.9%。 第一級固溶制度是影響板材力學(xué)性能的主要因素， 最佳固溶溫度為450 ℃。 在450 ℃進(jìn)行第一級固溶后， 樣品發(fā)生了較強(qiáng)的回復(fù)， 由于降低了再結(jié)晶驅(qū)動力， 第二級高溫固溶在獲得較高的合金元素過飽和度的同時(shí)， 僅發(fā)生較少的再結(jié)晶， 從而在隨后的時(shí)效過程中產(chǎn)生更高的析出強(qiáng)化效應(yīng)。
關(guān)鍵字: 7A55鋁合金； 再結(jié)晶； 回復(fù)； 雙級固溶； 力學(xué)性能
microstructures and mechanical properties of
7A55 aluminum alloy
LIU Wen-hui, ZHANG Chong, DU Yu-xuan
（School of Materials Science and Engineering, Central South University,
Changsha 410083, China）
Abstract: The effects of temperature and time of two-stage solution on mechanical properties of 7A55 aluminium alloy sheet were investigated by optical microscopy, TEM and SEM analyses and tensile testing and electrical conductivity test. The optimal two-stage solution treatment is 450 ℃, 90 min+485 ℃, 40 min. The mechanical properties σb, σ0.2 and δ reach 648.4 MPa, 629.6 MPa and 11.9%, respectively, after aging at 120 ℃ for 24 h. The results show that the first stage solution is crucial to the mechanical properties, and the optimal temperature is 450 ℃. The extensive recovery occurs after the first stage solution at 450 ℃, which reduces the driving force of recrystallization. Consequently, higher alloying elements supersaturation in matrix is obtained at the second stage high temperature solution and only little recrystallization happens. As a result, a better precipitation strengthening effect in subsequent aging is attained.
Key words: 7A55 aluminum alloy; recrystallization; recovery; two-stage solution; mechanical properties
