【摘要】：Al-Zn-Mg-Cu系超高強鋁合金,由于其優(yōu)異的綜合性能,被廣泛應(yīng)用于交通運輸、航空航天、兵器工業(yè)等領(lǐng)域。國內(nèi)外眾多學(xué)者也一直致力于該類合金的組織及性能研究,以滿足各應(yīng)用領(lǐng)域下不斷提高的材料性能要求。本文以自主制備的擠壓態(tài)超強鋁合金(Al-12.18Zn-3.31Mg-1.43Cu-0.20Zr-0.0435Sr)為實驗材料,通過對合金進行OM(光學(xué)顯微鏡)金相組織、EBSD(電子背散射衍射)、XRD(X射線衍射)分析與硬度、電導(dǎo)率、拉伸性能、抗腐蝕性能(晶間、剝落)測試,研究了變形工藝(軋制、等通道轉(zhuǎn)角擠壓(ECAP)、熱壓縮)、預(yù)回復(fù)退火、時效工藝對該材料組織及性能的影響,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、Z方向為擠壓態(tài)合金徑向,Y、Z方向間夾角為90°;ECAP加工中,Y方向與ECAP剪切面平行):探索出了一套采用常規(guī)熔鑄(非快速凝固)-擠壓-軋制(沿X方向)工藝,結(jié)合后續(xù)熱處理(預(yù)回復(fù)、固溶、T7X-2(121℃×5h+133℃×16h)時效),制備抗拉強度達809MPa,且具有良好抗腐蝕(晶間、剝落)性能超強鋁合金的方法。本文所研究合金經(jīng)軋制-預(yù)回復(fù)-固溶-T7X-2時效處理后,Z方向硬度達到了251.6HV,晶間、剝落腐蝕等級分別為四級和EB級;X方向抗拉強度達到了809.2MPa,斷裂延伸率為5.8%。預(yù)回復(fù)退火處理提升了軋制態(tài)合金的抗拉強度,對合金的抗腐蝕性能、硬度、電導(dǎo)率沒有明顯影響。合金的拉伸性能測試和EBSD組織分析結(jié)果表明合金的各向異性較小。本文所研究軋制態(tài)合金在T6(121℃×24h)與T7X-2時效下,抗晶間腐蝕性能相差不大,T7X-1(121℃×5h+153℃×16h)時效下,合金的抗晶間腐蝕性能最佳;T6、T7X-1時效下,合金的抗剝落腐蝕性能無明顯差異,較T7X-2時效下更優(yōu)。探索出了一套采用常規(guī)熔鑄(非快速凝固)-擠壓-ECAP(沿X方向)-熱壓縮工藝,結(jié)合后續(xù)熱處理(固溶、T6時效),制備抗拉強度達763MPa,且具有優(yōu)異抗腐蝕(晶間、剝落)性能超強鋁合金的方法。本文所研究合金經(jīng)ECAP-Z向熱壓縮-固溶-T6時效處理后,X、Y、Z方向硬度均超過240HV,晶間、剝落腐蝕等級分別為三級和EA級;X方向抗拉強度達到了763.6MPa,斷裂延伸率為5.0%。本文所研究合金ECAP加工后的兩種壓縮方向(Z、Y),對合金的硬度、電導(dǎo)率、抗腐蝕性能均無明顯影響。合金的抗腐蝕(晶間、剝落)性能測試和硬度測試結(jié)果表明合金的各向異性較小。Y向壓縮對合金的晶粒細化效果更顯著,合金經(jīng)ECAP-Y向熱壓縮-固溶處理后,X方向10μm以下晶粒所占百分比為78.1%,而沿Z向壓縮時,這一比例僅為55.2%。這是因為Y向壓縮時,合金的變形方向與ECAP剪切面近似呈90°,變形更劇烈。探索出了一套采用常規(guī)熔鑄(非快速凝固)-擠壓-C方式兩道次ECAP(沿X方向)-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),制備抗拉強度達778MPa,且具有優(yōu)異抗腐蝕(晶間、剝落)性能超強鋁合金的方法。本文所研究合金經(jīng)C方式兩道次ECAP-Z向熱壓縮-預(yù)回復(fù)-固溶-T7X-1時效處理后,X、Y、Z方向硬度均超過225HV,晶間、剝落腐蝕等級分別為三級和P級;X方向抗拉強度達到了778.4MPa,斷裂延伸率6.67%。本文所研究合金C方式兩道次ECAP加工后的兩種壓縮方向(Z、Y),對合金的電導(dǎo)率、抗腐蝕性能均無明顯影響;對合金的硬度有一定影響。本文所研究合金經(jīng)C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時效下的抗晶間、剝落腐蝕性能更優(yōu)。合金的抗腐蝕(晶間、剝落)性能測試和硬度測試結(jié)果表明合金的各向異性較小。
[Abstract]:Al-Zn-Mg-Cu is an ultra-high strength aluminum alloy, and is widely used in the fields of transportation, aerospace, and military industry and the like due to its excellent comprehensive performance. Many scholars at home and abroad have been working on the microstructure and performance of this kind of alloy, so as to meet the increasing material performance requirements under various application fields. In this paper, the self-prepared extruded super aluminum alloy (Al-12.18Zn-3.31Mg-1.43Cu-0.20Zr-0.0435Sr) is used as an experimental material, and the alloy is subjected to OM (optical microscope) metallographic structure, EBSD (electron backscatter diffraction), XRD (X-ray diffraction) analysis and hardness, electrical conductivity, tensile property and corrosion resistance (intergranular, The effect of deformation process (rolling, equal channel angular pressing (ECAP), thermal compression), pre-recovery annealing and aging process on the microstructure and properties of the material was studied. The main results are as follows (X direction is the axial direction of the extruded alloy, Y, in that Z direction, the included angle between the radial, Y and Z directions of the extruded alloy is 90 deg.; in the ECAP process, the Y direction is parallel to the shear plane of the ECAP): a set of conventional casting (non-rapid solidification)-extrusion-rolling (in the X direction) process is explored, and the subsequent heat treatment (pre-recovery, solid solution, T7X-2 (121 鈩，

本文編號：2494491