發(fā)布時間：2018-07-10 01:14

  本文選題：6061鋁合金 + 變形��； 參考：《江蘇大學(xué)》2017年碩士論文

【摘要】：6xxx系鋁合金因?yàn)榫哂械兔芏�、高比�?qiáng)度和較好的耐腐蝕性,被廣泛應(yīng)用于航空航天、汽車制造等領(lǐng)域。隨著對材料性能要求的提高,人們開始探索新的材料處理方式,以期獲得良好的綜合性能。本文以6061鋁合金為研究對象,經(jīng)不同變形與熱處理組合工藝處理,研究變形、預(yù)時效和中間熱處理方式對6061鋁合金硬度、拉伸性能、電導(dǎo)率和耐腐蝕性等的影響,并從金相組織、斷口掃描、XRD、透射電鏡等方面對變形與熱處理組合工藝處理后的試樣進(jìn)行微觀組織結(jié)構(gòu)分析,得出以下結(jié)論:(1)6061鋁合金固溶處理(540℃、3h)后在時效溫度為180℃、時效時間為4h時硬度最大,時效前的變形不僅能提高試樣峰值時效的硬度和強(qiáng)度,還能減少到達(dá)峰值時效的時間,且形變量越大,硬度和強(qiáng)度越高,到達(dá)峰值時效的時間越短,但塑性降低;在形變量都為50%的條件下,變形前不經(jīng)預(yù)時效處理的試樣最終的硬度為129.6HV,抗拉強(qiáng)度為368.32MPa,延伸率為22.10%,變形前經(jīng)預(yù)時效處理的試樣最終的硬度為136.7HV,抗拉強(qiáng)度為385.82MPa,延伸率為22.21%,可以看出變形前的預(yù)時效不僅能提高試樣的硬度和強(qiáng)度,還改善了6061鋁合金的塑性;在總變形量相同的條件下,中間經(jīng)過峰值時效的試樣最終的硬度和強(qiáng)度最高,但塑性最差,中間經(jīng)過再結(jié)晶處理的試樣塑性最好,但強(qiáng)度較低,中間經(jīng)過回復(fù)處理的試樣最終的硬度、強(qiáng)度和延伸率介于兩者之間。(2)固溶處理后的變形會降低6061鋁合金的電導(dǎo)率,且變形量越大,降低越嚴(yán)重;變形后的時效過程中6061鋁合金的電導(dǎo)率會隨著時效時間的延長逐漸提高,回復(fù)和再結(jié)晶處理都能提高6061鋁合金的電導(dǎo)率,且再結(jié)晶的作用更大。(3)時效前的變形能提高6061鋁合金的耐腐蝕性,且變形量越大合金的耐腐蝕性越好;變形量相同的條件下,變形前的預(yù)時效會降低6061鋁合金峰值時效后的耐腐蝕性;變形后經(jīng)回復(fù)和再結(jié)晶處理的試樣的耐腐蝕性要好于峰時效處理的試樣,且再結(jié)晶處理的作用更顯著,不同的中間熱處理方式對6061鋁合金最終的耐腐蝕性影響不同。(4)時效前的變形處理會使晶粒拉長,且變形量越大,晶粒拉長越明顯,變形后的再結(jié)晶處理會細(xì)化晶粒;時效前的變形不僅影響時效后衍射峰的強(qiáng)度,還會使衍射峰的位置發(fā)生偏移,變形后的熱處理方式只會影響6061鋁合金最終衍射峰的強(qiáng)度,而對衍射峰的位置影響不大。(5)不同變形與熱處理工藝下6061鋁合金的拉伸斷口都為韌性斷裂,變形、預(yù)時效和中間熱處理方式都會影響6061鋁合金最終的斷口形貌,時效前的變形量越大,斷口處大韌窩的數(shù)量越少,韌窩越淺,塑性越差;變形前的預(yù)時效可以改善6061鋁合金峰值時效后的塑性;變形后經(jīng)過再結(jié)晶處理的試樣晶粒細(xì)化,再經(jīng)變形時效后,斷口韌窩均勻分布,大韌窩的數(shù)量較多且韌窩較深,塑性較好。(6)時效前的變形會產(chǎn)生大量的位錯,形變量越大,位錯纏結(jié)越嚴(yán)重,且分布不均勻,變形量為50%時,產(chǎn)生形變亞結(jié)構(gòu);變形前經(jīng)預(yù)時效處理的試樣產(chǎn)生的形變亞結(jié)構(gòu)更明顯,且尺寸更均勻,塑性更好;變形后經(jīng)回復(fù)處理,晶體中的位錯密度略微降低,空位大量消失;變形后經(jīng)再結(jié)晶處理,位錯基本消失,再經(jīng)變形又產(chǎn)生位錯纏結(jié),合金強(qiáng)度升高。
[Abstract]:Because of its low density, high specific strength and good corrosion resistance, 6xxx aluminum alloy has been widely used in aerospace, automobile manufacturing and other fields. With the improvement of the material performance, people began to explore new material treatment methods in order to obtain good comprehensive performance. This paper is based on 6061 aluminum alloy, through different deformation and deformation. The effects of deformation, pre aging and intermediate heat treatment on the hardness, tensile properties, electrical conductivity and corrosion resistance of 6061 aluminum alloy were studied by the combined heat treatment process. The microstructure of the specimens after the combination process of deformation and heat treatment was analyzed from metallographic structure, fracture scanning, XRD, transmission electron microscope and so on. Conclusion: (1) the hardness and strength of peak aging of 6061 aluminum alloy after solid solution treatment (540 C, 3H) at aging temperature of 180 and aging time is 4h, and the time of peak aging can not only be increased, but also the greater the shape variable, the higher the hardness and strength, the shorter the time to peak aging, but the more the time, but the time of the peak aging is shorter. When the shape variables are 50%, the final hardness of the specimen without pre aging treatment is 129.6HV, the tensile strength is 368.32MPa, the elongation is 22.10%, the final hardness is 136.7HV, the tensile strength is 385.82MPa, and the elongation is 22.21% before deformation. It can be seen that pre deformation before deformation can not only be seen. It can improve the hardness and strength of the sample, and improve the plasticity of the 6061 aluminum alloy. Under the same total deformation, the final hardness and strength of the sample with peak aging is the highest, but the plasticity is the worst, the middle after recrystallization is the best plastic, but the strength is low, the final hardness of the sample retreated in the middle is the final. The strength and elongation are between the two. (2) the deformation of the solid solution will reduce the conductivity of the 6061 aluminum alloy, and the greater the deformation, the more serious. The electrical conductivity of the 6061 aluminum alloy will increase gradually with the aging time, and the electrical conductivity of the 6061 aluminum alloy can be increased by the recovery and recrystallization, and the electrical conductivity of 6061 aluminum alloy can be improved. The effect of crystallization is greater. (3) the deformation before aging can improve the corrosion resistance of 6061 aluminum alloy, and the greater the amount of deformation, the better the corrosion resistance of the alloy. Under the same deformation quantity, the pre aging of the deformation will reduce the corrosion resistance of the 6061 aluminum alloy after the peak aging; the corrosion resistance of the specimen treated by recovery and recrystallization is better than that of the specimen treated after the deformation. The effect of the recrystallization treatment is more significant. The effect of different intermediate heat treatment on the final corrosion resistance of 6061 aluminum alloy is different. (4) the deformation treatment before aging makes the grain elongate, and the larger the deformation, the more obvious the grain length is, the recrystallization will refine the grain after the deformation; the deformation before aging is not only the shadow. The intensity of the diffraction peak will also offset the position of the diffraction peak, and the heat treatment after deformation only affects the strength of the final diffraction peak of 6061 aluminum alloy, but has little effect on the position of the diffraction peak. (5) the tensile fracture of 6061 aluminum alloy under different deformation and heat treatment process are all ductile fracture, deformation, preaging and intermediate heat. The shape of 6061 aluminum alloy will affect the final fracture morphology of aluminum alloy. The greater the deformation amount before aging, the less the number of dimples at the fracture surface, the shallower of the dimple and the worse the plasticity; the predeformation before the deformation can improve the plasticity after the peak aging of the 6061 aluminum alloy; the grain refinement after the recrystallization, and then the fracture toughness after deformation aging, is toughened. The nests are evenly distributed, the number of large dimples is more and the ductility is deeper and the plasticity is better. (6) the deformation will produce a large number of dislocation, the larger the shape variable, the more serious the dislocation entanglement, the unevenly distributed, the deformation substructure when the deformation amount is 50%, and the deformation substructure is more obvious and the size is more uniform before the deformation of the pretreated sample. After the deformation of the crystal, the dislocation density in the crystal is slightly reduced and the vacancy disappears. After recrystallization, the dislocation basically disappeared, and then the dislocation entangled and the strength of the alloy increased.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG146.21;TG166.3

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本文編號：2111445