【摘要】：由于半固態(tài)成形工藝過程中熔體存在強制對流現(xiàn)象，導致含銅鋁合金在凝固過程中出現(xiàn)Cu元素偏聚現(xiàn)象，而合金中含有Fe元素時，也會對這種Cu元素的偏聚現(xiàn)象產(chǎn)生影響。分析這種現(xiàn)象產(chǎn)生的原因及規(guī)律，對認識半固態(tài)加工鋁合金中的Cu元素分布行為，以及對合金制備、熱處理工藝的制定和研究開發(fā)適合半固態(tài)成形的新工藝均具有理論意義和實用價值。 本文研究了半固態(tài)制坯、二次加熱重熔和觸變成形階段對Al-Fe-4Cu合金中Cu元素偏聚的影響，并研究了熱處理工藝與合金性能的關系。獲得了半固態(tài)制坯和二次加熱重熔階段合金中Cu元素偏聚規(guī)律，以及合適的強化熱處理工藝。實驗中選用了不同的電磁攪拌電流以及不同的二次加熱溫度等工藝參數(shù)，分析了工藝因素與Cu元素偏聚的關系，目的是為半固態(tài)加工工藝的制定提供指導；通過正交試驗分析了時效處理工藝參數(shù)對合金性能的影響，從而實現(xiàn)了熱處理工藝的優(yōu)化。 不加電磁攪拌電流實驗結(jié)果表明，Cu元素在晶界處發(fā)生偏聚，且偏聚十分明顯；施加不同電磁攪拌強度實驗表明，電磁攪拌有利于改善Cu元素的偏聚現(xiàn)象，，當攪拌電流分別為40A、60A、80A和100A情況下，攪拌電流越大，改善銅元素在制坯階段的偏聚現(xiàn)象越明顯。二次加熱重熔實驗表明，在分別采用650℃、660℃、670℃和680℃進行二次加熱重熔實驗時，重熔區(qū)內(nèi)的Cu元素趨于均勻分布，且加熱溫度越高，重熔區(qū)越大，在重熔區(qū)內(nèi)的Cu元素分布月均勻；觸變成形后，Cu元素在富Fe相表面出現(xiàn)了偏聚現(xiàn)象；合金熱處理正交實驗結(jié)果表明，當熱處理工藝為520℃固溶10h然后進行175℃的4h人工時效時，合金的硬度達到最高值。
[Abstract]:Due to the phenomenon of forced convection in the melt during semisolid forming process, the phenomenon of Cu segregation occurs in the solidification process of Cu-containing aluminum alloy, and when the alloy contains Fe element, it will also have an effect on the segregation of this kind of Cu element. The causes and rules of this phenomenon are analyzed, and the distribution behavior of Cu elements in semi-solid processing aluminum alloy and the preparation of the alloy are analyzed. The formulation of heat treatment process and the research and development of a new process suitable for semi-solid forming are of theoretical significance and practical value. In this paper, the effect of semi-solid billet making, secondary heating remelting and thixoforming on the segregation of Cu elements in Al-Fe-4Cu alloy is studied, and the relationship between heat treatment process and the properties of the alloy is also studied. The segregation rule of Cu elements in semi-solid billets and secondary heating remelting alloys was obtained, and the appropriate strengthening heat treatment process was also obtained. In the experiment, different electromagnetic stirring current and different secondary heating temperature were selected to analyze the relationship between the process factors and the segregation of Cu elements, in order to provide guidance for the formulation of semi-solid processing technology. The influence of aging process parameters on the properties of the alloy was analyzed by orthogonal test, and the heat treatment process was optimized. The results of experiments without electromagnetic stirring current show that the segregation of Cu elements at grain boundaries is very obvious, and the experiment of different electromagnetic stirring intensity shows that electromagnetic stirring can improve the segregation of Cu elements. When the stirring current is 40A, 60A, 80A and 100A respectively, the bigger the stirring current is, the more obvious is the phenomenon of improving the segregation of copper element in the process of billet production. The secondary heating remelting experiments show that the Cu elements in the remelting zone tend to distribute uniformly when the remelting experiments are carried out at 650 鈩

本文編號：2274033