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  本文關(guān)鍵詞：稀土釔、鈧及時效工藝對A357合金組織與性能的影響　出處：《南昌大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： A357合金 細(xì)化和變質(zhì) 熱處理 組織力學(xué)性能

【摘要】：A357合金是一種典型的亞共晶Al-Si-Mg合金,由于它有優(yōu)良的鑄造性能和力學(xué)性能,被廣泛應(yīng)用于航空航天、汽車等工業(yè)領(lǐng)域。本文以A357合金為研究對象,利用金相顯微鏡、布氏硬度機、萬能電子拉伸機、XRD和掃描電鏡等分析測試儀器,通過在熔體中添加Al-5Ti-B、Al-10Sr、微量Sc和Y,研究細(xì)化變質(zhì)劑對合金組織性能的影響,以期通過優(yōu)化熔體細(xì)化變質(zhì)工藝,改善合金組織與力學(xué)性能。研究表明:0.3%Y、0.3%Sc均能明顯細(xì)化合金的α-Al晶粒,并改善共晶硅的形態(tài),但Y的細(xì)化效果不及等量Sc;0.3%Y、0.2%Sc能夠明顯改變共晶硅的形貌,具一定的變質(zhì)效果,但Y對共晶硅的變質(zhì)效果強于Sc。Y提高合金鑄態(tài)力學(xué)性能幅度也要大于Sc。將Y與傳統(tǒng)Al-5Ti-B+Al-10Sr細(xì)化變質(zhì)聯(lián)合添加,三者之間未見相互干擾作用。與傳統(tǒng)Al-5Ti-B+Al-10Sr細(xì)化變質(zhì)效果相比,添加稀土Y使α-Al二次枝晶間距從15.4 um變成14.1 um,小幅增加細(xì)化效果;添加稀土Y明顯強化對共晶硅的變質(zhì)效果;在傳統(tǒng)Al-5Ti-B+Al-10Sr細(xì)化變質(zhì)處理的基礎(chǔ)上添加稀土Y,合金抗拉強度和延伸率分別提升了4.5%和0.5%。在添加Al-5Ti-B和Sr的基礎(chǔ)上,添加稀土Y后,并未明顯改變合金的最佳固溶溫度和時效溫度,其最佳的時效工藝為548oC固溶處理12 h+175oC時效6 h。與經(jīng)傳統(tǒng)Al-5Ti-B+Al-10Sr細(xì)化變質(zhì)處理的合金相比,再添加稀土Y使合金熱處理后的抗拉強度提升2.1%、延伸率提升29%。
[Abstract]:A357 alloy is a typical hypoeutectic Al-Si-Mg alloy. Because of its excellent casting and mechanical properties, it is widely used in aerospace, automobile and other industrial fields. In this paper, A357 alloy as the research object, by using metallurgical microscope and Brinell hardness tester, universal electronic tensile machine, XRD and scanning electron microscopy analysis test instrument, by adding Al-5Ti-B, Al-10Sr, Sc and Y trace in the melt, of refinement modifier on Microstructure and properties of the influence, in order to optimize the melt modification process to improve the microstructure and mechanical properties of the alloy. The results show that 0.3%Y and 0.3%Sc can significantly refine the grain of alpha -Al and improve the morphology of eutectic silicon, but the refinement effect of Y is not equal to that of Sc. 0.3%Y and 0.2%Sc can obviously change the morphology of eutectic silicon and have certain modification effect, but Y has greater modification effect on eutectic silicon than Sc. The increase of the mechanical properties of the cast alloy by Y is greater than that of Sc. The combination of Y and traditional Al-5Ti-B+Al-10Sr was added, and there was no mutual interference between the three. Compared with the traditional Al-5Ti-B+Al-10Sr modification effect of refinement, adding Y to a -Al two primary dendrite spacing from 15.4 um to 14.1 um, a small increase in refining effect; adding Y significantly enhanced modification effect on eutectic silicon; adding Y based on traditional Al-5Ti-B+Al-10Sr grain refinement and modification on the tensile strength and elongation of the alloy. Up to 4.5% and 0.5%. On the basis of adding Al-5Ti-B and Sr, adding rare earth Y did not significantly change the best solution temperature and aging temperature of the alloy. The best aging process was 548oC solid solution treatment 12 h+175oC aging 6 h. With the addition of rare earth Y, the tensile strength of the alloy after heat treatment is increased by 2.1% and the elongation increase by 29%, compared with the alloy refined by the traditional Al-5Ti-B+Al-10Sr.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG146.21;TG166.3

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本文編號：1342449