新型高合金化7xxx系铝合金淬火敏感性研究
发布时间：2019-02-27 15:47
【摘要】：追求更高的强度级别及更佳的综合性能是7xxx系铝合金永恒的发展主题,提高其合金化程度已成为7xxx系铝合金成分设计的主要方向。然而,高合金化会直接增加7xxx系铝合金的淬火敏感性,影响新型高合金化7xxx系铝合金在航空航天等领域厚截面整体式构件制造中的应用。本文结合直接淬火试验、末端淬火试验和分级淬火试验,对比分析了新型高合金化7xxx系铝合金过饱和固溶体的稳定性和脱溶析出行为,系统研究了主合金化元素Mg、Cu、Zn以及微合金化元素Zr的含量对合金淬火敏感性的影响规律,为新型高合金化7xxx系铝合金的生产与应用提供技术支撑。通过对残留相回溶及组织过烧情况的分析,确定了合金适宜的固溶制度为470～472℃/6h。采用直接淬火试验结合XRD精确测定合金晶格常数研究了合金过饱和固溶体的稳定性,研究发现,升高Mg、Zn、Zr含量会使合金固溶体晶格常数增大,升高Cu含量会使合金固溶体晶格常数减小,其中Cu元素对合金晶格畸变的影响程度最大;Mg、Cu、Zn、Zr含量升高均会导致合金过饱和固溶体的稳定性下降,在同等原子量添加时,Cu元素的影响作用更明显。研究了末端淬火试验过程中合金的电导率和硬度变化、淬透深度及脱溶析出行为。随着淬火冷却速率降低,合金的淬火态电导率增大,时效态硬度减小;本试验合金的淬透深度约为40～75mm,临界冷却速率为2.12～4.78K/s。升高Mg、Cu、Zn、Zr含量均会使合金的电导率及硬度变化总幅度增大、淬透深度减小,会加剧末端淬火过程中固溶体脱溶析出的趋势,在晶界上优先脱溶出长条状的η相,并随着淬火冷却速率的降低而粗化;当淬火冷却速率降至临界冷却速率以下时,晶内也会发生脱溶析出,η相主要依附于Al3Zr粒子析出。研究了分级淬火试验过程中合金的电导率和硬度变化、TTP曲线及脱溶析出行为。分级淬火温度310℃和340℃合金性能对保温时间的响应速度最快,延长保温时间,合金的淬火态电导率呈上升趋势,时效态硬度呈下降趋势。本试验合金的鼻温范围为300～320℃,鼻温孕育期范围为0.867～3.358s。升高Mg、Cu、Zn、Zr含量均会缩短合金TTP曲线的鼻温孕育期,会加剧分级淬火过程中固溶体脱溶析出的趋势,在晶界上优先脱溶出棒状的η相,随保温时间的延长而粗化,并在晶内依附于部分Al3Zr粒子脱溶析出η相;合金经时效后,在这些粗大的η相周围形成了一定尺寸的无沉淀析出区。综合直接淬火试验、末端淬火试验和分级淬火试验结果表明,本文试验范围内,升高Mg、Cu、Zn、Zr含量均会导致新型高合金化7xxx系铝合金过饱和固溶体的稳定性下降,淬火敏感性增加,其中Cu、Mg含量的影响更为显著。
[Abstract]:It is the eternal development theme of 7xxx series aluminum alloy to pursue higher strength level and better comprehensive properties. It has become the main direction of composition design of 7xxxx aluminum alloy to improve its alloying degree. However, high alloying will directly increase the quenching sensitivity of 7xxxx aluminum alloy, which will affect the application of the new high alloyed 7xxxx aluminum alloy in the manufacture of thick section monolithic components in aerospace and other fields. In this paper, the stability and precipitation behavior of supersaturated solid solution of a new type of high alloyed 7xxxx aluminum alloy have been compared and analyzed by means of direct quenching test, end quenching test and step quenching test. The main alloying element Mg,Cu, has been systematically studied. The influence of the content of Zn and microalloying element Zr on the quenching sensitivity of the alloy provides technical support for the production and application of a new type of high alloyed 7xxx aluminum alloy. Through the analysis of the residual phase remelting and microstructure overburning, the suitable solid solution system was determined to be 470 鈩，
本文编号：2431399
[Abstract]:It is the eternal development theme of 7xxx series aluminum alloy to pursue higher strength level and better comprehensive properties. It has become the main direction of composition design of 7xxxx aluminum alloy to improve its alloying degree. However, high alloying will directly increase the quenching sensitivity of 7xxxx aluminum alloy, which will affect the application of the new high alloyed 7xxxx aluminum alloy in the manufacture of thick section monolithic components in aerospace and other fields. In this paper, the stability and precipitation behavior of supersaturated solid solution of a new type of high alloyed 7xxxx aluminum alloy have been compared and analyzed by means of direct quenching test, end quenching test and step quenching test. The main alloying element Mg,Cu, has been systematically studied. The influence of the content of Zn and microalloying element Zr on the quenching sensitivity of the alloy provides technical support for the production and application of a new type of high alloyed 7xxx aluminum alloy. Through the analysis of the residual phase remelting and microstructure overburning, the suitable solid solution system was determined to be 470 鈩，
本文编号：2431399
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