發(fā)布時間：2018-03-31 09:04

  本文選題：超高強(qiáng)鋁合金　切入點：ECAP　出處：《江蘇大學(xué)》2017年碩士論文

【摘要】：7000系鋁合金憑借其自身具備的密度小、比強(qiáng)度高、抗腐蝕性能好等優(yōu)點被廣泛應(yīng)用在航空航天、武器制造、汽車船舶等制造業(yè)領(lǐng)域。本文以自主創(chuàng)新研制的超高強(qiáng)鋁合金(wt.%)Al-12.51Zn-2.85Mg-2.83Cu-0.18Zr-0.0598Sr擠壓材為試驗材料,通過金相組織、Electron Backscattered Diffraction(EBSD)、X-ray diffraction(XRD)、顯微硬度、電導(dǎo)率、拉伸性能及斷口特征、晶間腐蝕與剝落腐蝕性能等方法,研究了擠壓、軋制、ECAP(等通道轉(zhuǎn)角擠壓)、熱壓縮等變形加工及后續(xù)熱處理對鋁合金組織性能的影響,主要研究結(jié)果如下(下文中X方向為擠壓態(tài)合金軸向,Y方向與ECAP剪切面平行,Z方向為Y方向沿軸向旋轉(zhuǎn)90°):探索出了一套采用常規(guī)熔鑄(非快速凝固)-擠壓-軋制工藝,結(jié)合后續(xù)熱處理(預(yù)回復(fù)、固溶、T7X-2時效),制備抗拉強(qiáng)度達(dá)716MPa,且具有良好抗腐蝕(晶間、剝落)性能超高強(qiáng)鋁合金的方法。本文所研究合金經(jīng)軋制-預(yù)回復(fù)-固溶-T7X-2(121℃×5 h+133℃×16 h)時效處理后,Z方向硬度達(dá)到232.8HV,晶間、剝落腐蝕等級為三級(62.33μm)和EC級;X方向抗拉強(qiáng)度達(dá)到716.39MPa,斷裂延伸率為8.76%。預(yù)回復(fù)退火處理促進(jìn)了第二相的回溶,保留了較多位錯,提升了軋制態(tài)合金的抗拉強(qiáng)度,提高了合金的電導(dǎo)率與抗腐蝕性能。由合金的拉伸性能測試和XRD組織分析結(jié)果顯示,軋制材在X、Y方向的微結(jié)構(gòu)與力學(xué)性能存在明顯的各向異性。本文所研究軋制態(tài)合金在T6(121℃×24 h)與T7X-2時效下,抗(晶間、剝落)腐蝕性能相差不大,T7X-1(121℃×5 h+153℃×16 h)時效下,合金的抗腐蝕性能最佳。探索出了一套采用常規(guī)熔鑄(非快速凝固)-擠壓-過時效-ECAP-熱壓縮工藝,結(jié)合后續(xù)熱處理(固溶、T6時效),制備抗拉強(qiáng)度達(dá)696MPa,且具有較好抗腐蝕(晶間、剝落)性能超高強(qiáng)鋁合金的方法。本文所研究合金經(jīng)ECAP-Y向熱壓-固溶-T6(121℃×24 h)時效處理后,X、Y、Z方向硬度均超過220HV,晶間腐蝕深度均小于131μm、剝落腐蝕等級均達(dá)到EC級;X方向抗拉強(qiáng)度達(dá)到696.76MPa,斷裂延伸率為7.67%。本文所研究的合金在兩種熱壓工藝下的強(qiáng)度、硬度、電導(dǎo)率、抗晶間性能都呈現(xiàn)明顯差異。在微結(jié)構(gòu)方面由EBSD與XRD數(shù)據(jù)分析可以得出,Y向熱壓下合金發(fā)生了動態(tài)連續(xù)再結(jié)晶使晶粒平均尺寸得到細(xì)化,晶界平均角度略微變大,低角度晶界百分比降低。這都是由于Y向熱壓的剪切方向與ECAP擠壓的剪切方向夾角更接近于90°,其塑性變形更劇烈所產(chǎn)生的現(xiàn)象。探索出了一套采用常規(guī)熔鑄(非快速凝固)-擠壓-過時效-Bc方式兩道次ECAP-熱壓縮工藝,結(jié)合后續(xù)熱處理(預(yù)回復(fù)、固溶、T7X-1時效),制備抗拉強(qiáng)度達(dá)688MPa,且具有優(yōu)異抗腐蝕(晶間、剝落)性能超高強(qiáng)鋁合金的方法。本文所研究合金經(jīng)Bc方式兩道次ECAP-Z向熱壓-預(yù)回復(fù)-固溶-T7X-1時效處理后,X、Y、Z方向硬度均超過214HV,晶間腐蝕深度均小于126μm、剝落腐蝕等級均達(dá)到EA級;X方向抗拉強(qiáng)度達(dá)到688.20MPa,斷裂延伸率6.67%。本文所研究合金經(jīng)Bc方式兩道次ECAP加工后,兩種壓縮方向(Z、Y)下合金的微結(jié)構(gòu)(平均晶粒尺寸、平均晶界角度、小角度晶界比例)方面呈現(xiàn)較小差異,并且兩種熱壓工藝對合金的硬度、電導(dǎo)率、抗腐蝕性能均無明顯影響;說明Bc兩道次ECAP可以更大程度上改善了材料微結(jié)構(gòu)與抗腐蝕性能的各項異性。本文所研究合金經(jīng)Bc方式兩道次ECAP-熱壓縮-預(yù)回復(fù)-固溶處理后,相較T6時效,T7X-1時效下抗腐蝕(晶間、剝落)性能更優(yōu)。
[Abstract]:7000 Aluminum Alloy with its own low density, high specific strength, good corrosion resistance and other advantages are widely used in aerospace, weapons manufacturing, automobile and ship manufacturing. This paper developed on the independent innovation of ultra high strength Aluminum Alloy (wt.%) Al-12.51Zn-2.85Mg-2.83Cu-0.18Zr-0.0598Sr profile as the test material, through the microstructure, Electron Backscattered Diffraction (EBSD), X-ray diffraction (XRD), microhardness, electrical conductivity, tensile properties and fracture characteristics, method of corrosion and exfoliation corrosion properties of intergranular, rolling, extrusion, ECAP (ECAP), hot compression deformation and subsequent heat treatment effect on Aluminum Alloy performance. The main results are as follows (X direction below for extruded alloy axial, parallel, Y direction and ECAP direction is Y Z shear plane along the direction of axial rotation of 90 DEG): To explore a set of used Conventional casting (non rapid solidification) - extrusion rolling process, combined with subsequent heat treatment (pre recovery, solid solution, aging, T7X-2) preparation of tensile strength of 716MPa, and has good corrosion resistance (intergranular flaking method) properties of ultra high strength Aluminum Alloy. This paper studies alloy by rolling - pre - reply the solution of -T7X-2 (121 DEG C * 5 h+133 * 16 h) after aging treatment, Z hardness of 232.8HV, intergranular and exfoliation corrosion grade is three (62.33 m) and EC; X direction tensile strength reaches 716.39MPa, the elongation rate of 8.76%. pre annealing treatment promoted back to the second phase solution, retain more wrong, enhance the tensile strength of rolled alloy, improve the electrical conductivity of the alloy and corrosion resistance. The tensile test and XRD microstructure analysis showed that the rolling material in X, microstructure and mechanical properties of Y direction is highly anisotropic. In this paper, the research on rolling 鎬佸悎閲戝湪T6(121鈩兠，

本文編號：1690051