本文選題：7055鋁合金　切入點(diǎn)：淬火殘余應(yīng)力　出處：《北京有色金屬研究總院》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：7055鋁合金屬于可熱處理強(qiáng)化的Al-Zn-Mg-Cu系變形鋁合金,具有超高強(qiáng)度和良好的綜合性能,其厚板產(chǎn)品被國際上廣泛應(yīng)用于航空航天等領(lǐng)域重要結(jié)構(gòu)件的制造。7055鋁合金厚板在航空用戶使用過程中存在著因殘余應(yīng)力偏大導(dǎo)致結(jié)構(gòu)件機(jī)加工過程中易出現(xiàn)變形超差甚至開裂的問題。淬火殘余應(yīng)力是厚板中殘余應(yīng)力存在的源頭,本文針對7055鋁合金厚板淬火殘余應(yīng)力分布規(guī)律開展測量與數(shù)值模擬研究,可為其工業(yè)化生產(chǎn)工藝的優(yōu)化制定提供實(shí)驗(yàn)基礎(chǔ),研究工作具有實(shí)用價值和理論意義。對比研究了X射線衍射法和鉆孔法測量表征7055鋁合金厚板表面淬火殘余應(yīng)力的可靠性。與X射線衍射法相比,鉆孔法測量結(jié)果的穩(wěn)定性較好,適于7055鋁合金厚板表面殘余應(yīng)力的測量。采用裂紋柔度法測量分析了7055鋁合金厚板內(nèi)部淬火殘余應(yīng)力的分布規(guī)律。淬火殘余應(yīng)力沿厚度方向軋向分應(yīng)力和橫向分應(yīng)力的分布規(guī)律相似,均表現(xiàn)出表面為壓應(yīng)力狀態(tài),心部為拉應(yīng)力狀態(tài);表面應(yīng)力的軋向分應(yīng)力最大值為-110MPa,橫向分應(yīng)力最大值為-140MPa,心部應(yīng)力的軋向分應(yīng)力最大值為130MPa,橫向分應(yīng)力最大值為115MPa。采用鉆孔法系統(tǒng)測量評價了7055鋁合金厚板在不同淬火條件(淬火介質(zhì)種類、溫度和濃度)下表面淬火殘余應(yīng)力的變化規(guī)律。淬火介質(zhì)(20℃)的冷卻能力順序?yàn)?15%PAG10%PAG5%PAG水10%NaCl;隨水溫或PAG濃度的升高,厚板表面淬火殘余應(yīng)力水平降低;水溫從20℃升至80℃時,厚板表面淬火殘余應(yīng)力軋向分應(yīng)力值從-187.1MPa降低到-88.0MPa,橫向分應(yīng)力值從-225.7MPa降低到-45.3MPa,表面淬火殘余應(yīng)力水平降低達(dá)50%以上;與5%PAG溶液相比,淬火介質(zhì)PAG濃度升至15%時,厚板表面淬火殘余應(yīng)力軋向分應(yīng)力降低比例達(dá)52.2%,橫向分應(yīng)力降低比例達(dá)47.2%。結(jié)合厚板峰時效態(tài)性能對比發(fā)現(xiàn),經(jīng)10%NaCl水溶液淬火處理后,厚板具有最高的強(qiáng)度性能,但淬火殘余應(yīng)力處于最高水平;經(jīng)15%PAG水溶液淬火處理后,厚板淬火殘余應(yīng)力水平顯著降低,但強(qiáng)度性能較前者降低了22.9MPa。通過測定7055鋁合金厚板物性參數(shù)等,利用建立的有限元模型,數(shù)值模擬研究了7055鋁合金厚板淬火殘余應(yīng)力的分布規(guī)律,經(jīng)淬火處理后,7055鋁合金厚板表面淬火殘余應(yīng)力為壓應(yīng)力,心部淬火殘余應(yīng)力為拉應(yīng)力,經(jīng)實(shí)測結(jié)果進(jìn)行驗(yàn)證,表明與數(shù)值模擬預(yù)測結(jié)果基本吻合。并研究了厚板尺寸對淬火殘余應(yīng)力水平的影響,隨著厚板厚度的增加,淬火殘余應(yīng)力水平呈明顯增大趨勢,當(dāng)板厚增至80mm以后,淬火殘余應(yīng)力的增速有所減緩。
[Abstract]:7055 aluminum alloy belongs to the heat treatment strengthened Al-Zn-Mg-Cu system deformed aluminum alloy, it has super high strength and good comprehensive properties. Its thick plate products are widely used in the manufacture of important structural parts in aerospace and other fields. 7055 aluminum alloy thick plate is easy to change in machining process because of the large residual stress in the course of aeronautical users' use. Quenching residual stress is the source of residual stress in thick plate. In this paper, the measurement and numerical simulation are carried out on the distribution of quenching residual stress in 7055 aluminum alloy thick plate, which can provide the experimental basis for the optimization of industrial production process. The research work is of practical value and theoretical significance. The reliability of X-ray diffraction method and borehole method for measuring surface quenching residual stress of 7055 aluminum alloy thick plate is compared with that of X-ray diffraction method. The stability of the results measured by drilling method is good. It is suitable for measuring the surface residual stress of 7055 aluminum alloy thick plate. The distribution of quenching residual stress in 7055 aluminum alloy thick plate is measured and analyzed by crack flexibility method. The distribution of stress is similar. The surface is in the state of compressive stress and the center is in the state of tensile stress. The maximum of surface stress is -110MPa, the maximum of transverse stress is -140MPa, the maximum of center stress is 130MPa, and the maximum of transverse stress is 115MPa. Same quenching conditions (type of quenchant, The order of cooling capacity of quenching medium is: 1: 15 PAG10PAG5PAG5PAG water 10NaCl1; with the increase of water temperature or PAG concentration, the surface quenching residual stress level of thick plate decreases; when water temperature rises from 20 鈩，

本文編號：1629714