本文選題：7005鋁合金 + 半固態(tài)坯料�。� 參考：《哈爾濱工業(yè)大學(xué)》2017年碩士論文

【摘要】：隨著輕量化、節(jié)能化的需求,7005鋁合金結(jié)構(gòu)件憑借其良好的理化性能被廣泛應(yīng)用到航空航天、機(jī)械、汽車、能源、國防等領(lǐng)域。目前,鋁合金傳統(tǒng)的成形加工技術(shù)有凝固成形和塑性成型兩種,凝固成形結(jié)構(gòu)件力學(xué)性能較差,塑性成形不能制造形狀復(fù)雜結(jié)構(gòu)件;金屬半固態(tài)成形技術(shù)是一種近凈成形技術(shù),在制備高質(zhì)量結(jié)構(gòu)件的應(yīng)用方面效果顯著,7005鋁合金的半固態(tài)成形技術(shù)也將會(huì)成為未來主流的金屬成形方式。對(duì)于半固態(tài)金屬成形技術(shù),制備高質(zhì)量的半固態(tài)坯料是關(guān)鍵,本文采用等通道往復(fù)擠壓與等溫處理兩個(gè)過程實(shí)現(xiàn)大變形應(yīng)變誘導(dǎo)等溫球晶化方法制備7005鋁合金半固態(tài)坯料,研究擠壓溫度、熱處理、等溫溫度、等溫時(shí)間等參數(shù)對(duì)材料微觀組織和力學(xué)性能的影響規(guī)律,探索坯料制備的最佳工藝參數(shù)。本文通過Deform-3D軟件對(duì)等通道往復(fù)擠壓過程進(jìn)行模擬仿真,得到在不同沖頭位移時(shí),材料應(yīng)力、應(yīng)變的變化情況;同時(shí)也對(duì)不同擠壓溫度、疊加坯料擠壓等狀態(tài)進(jìn)行模擬仿真。分析發(fā)現(xiàn):擠壓過程中,材料的應(yīng)力、應(yīng)變隨著沖頭位移的增加而增加;隨著擠壓溫度的升高,材料的應(yīng)力、應(yīng)變減小,且應(yīng)力集中區(qū)域變小;疊加坯料擠壓時(shí),坯料間接觸處產(chǎn)生了畸形應(yīng)變和應(yīng)力集中區(qū)域。通過等通道往復(fù)擠壓工藝對(duì)鑄態(tài)7005鋁合金進(jìn)行晶粒細(xì)化處理,借助金相顯微鏡、拉伸試驗(yàn)機(jī)、電子背散射衍射(EBSD)技術(shù)、掃描電鏡(SEM)對(duì)擠壓過程中材料微觀組織形貌、組成和力學(xué)性能進(jìn)行測試分析,研究各參數(shù)對(duì)坯料微觀組織和力學(xué)性能的影響規(guī)律;研究表明:經(jīng)過等通道往復(fù)擠壓后,坯料晶粒細(xì)化明顯,晶粒致密度增加,材料力學(xué)性能提高;疊加坯料擠壓實(shí)驗(yàn)中,隨著變形量的增加,材料晶粒細(xì)化效果更佳;連續(xù)擠壓實(shí)驗(yàn)則表明,隨著擠壓溫度的增加,坯料晶粒尺寸先減小后增大,在擠壓溫度為400℃時(shí)擠壓晶粒細(xì)化效果更好。將擠壓后的坯料加熱到半固態(tài)溫度進(jìn)行等溫處理實(shí)驗(yàn),利用金相顯微鏡、IPP圖像處理軟件、能譜分析儀(EDS)等設(shè)備,觀察并分析材料微觀組織在等溫處理過程中的演變規(guī)律。分析發(fā)現(xiàn),隨著等溫溫度和等溫時(shí)間的增加,晶粒尺寸和形狀系數(shù)保持增加,但溫度較高時(shí),晶粒平均直徑減小;Fe、Mn、Cu等元素形成共晶相,在等溫處理過程中先熔化形成液相。得出最佳工藝參數(shù):擠壓溫度為400℃,材料在610℃保溫20min或在615℃保溫15min。在對(duì)等溫處理過程分析的基礎(chǔ)上,提出大變形應(yīng)變誘導(dǎo)等溫球晶化制備7005鋁合金半固態(tài)坯料的新方法。
[Abstract]:With the light weight and energy saving demand, the aluminum alloy structural parts have been widely used in aerospace, machinery, automobile, energy, national defense and other fields with its good physical and chemical properties.At present, the traditional forming technology of aluminum alloy includes solidification forming and plastic forming, the mechanical properties of solidified forming structural parts are poor, and plastic forming can not make complex structural parts, the metal semi-solid forming technology is a kind of near net forming technology.The semisolid forming technology of 7005 aluminum alloy, which has remarkable effect in the preparation of high quality structural parts, will also become the mainstream metal forming method in the future.For the semisolid metal forming technology, the preparation of high quality semi-solid billets is the key. In this paper, 7005 aluminum alloy semi-solid billets are prepared by means of large strain induced isothermal spheroidization by equal channel reciprocating extrusion and isothermal treatment.The effects of extrusion temperature, heat treatment, isothermal temperature and isothermal time on the microstructure and mechanical properties of the material were studied.In this paper, the process of reciprocating extrusion with equal channel is simulated by Deform-3D software, and the change of material stress and strain under different punch displacement is obtained. At the same time, the state of extrusion temperature and superposition billet extrusion are simulated.It is found that the stress and strain of the material increase with the increase of the punch displacement during extrusion, the stress and strain of the material decrease with the increase of extrusion temperature, and the stress concentration area becomes smaller.The abnormal strain and stress concentration area are produced at the contact between the billets.The grain size of as-cast 7005 aluminum alloy was refined by the equal channel reciprocating extrusion process. The microstructure and morphology of the as-cast 7005 aluminum alloy were studied by means of metallographic microscope, tensile testing machine, electron backscatter diffraction (EBSD) technique and scanning electron microscope (SEM).The composition and mechanical properties were tested and analyzed, and the effects of various parameters on the microstructure and mechanical properties of the billet were studied.In the superposition blank extrusion experiment, the grain refinement effect is better with the increase of deformation, and the continuous extrusion experiment shows that the grain size of the blank decreases first and then increases with the increase of extrusion temperature.When the extrusion temperature is 400 鈩，

本文編號(hào)：1773739