双辊薄带振动铸轧振动工艺对凝固组织影响机理实验研究

发布时间：2018-01-04 11:10

本文关键词：双辊薄带振动铸轧振动工艺对凝固组织影响机理实验研究　出处：《燕山大学》2015年硕士论文　论文类型：学位论文

【摘要】：双辊薄带铸轧作为一种近终成形铸轧技术手段,相对传统连铸具有能耗低、效率高等优势。然而部分传统双辊铸轧板带坯存在组织不均匀,晶粒粗大,柱状晶发达,成分偏析严重等缺陷,最终会降低材料力学性能。针对这些缺陷,振动式双辊薄带铸轧机,在传统双辊薄带铸轧技术基础上,通过在单侧结晶辊上施加激振源改变流场和温度场,达到细化组织,减轻偏析的效果。本文针对此种振动工艺对金属组织影响规律开展了实验研究。利用振动式双辊薄带铸轧机作为振动实验平台,自主设计了振动铸造的实验方案,并完成了实验设备的设计、加工、装配以及调试工作。将振动铸造实验结果,与常规铸造工艺铸件,急速冷却无振动铸造工艺铸件进行实验对比分析,通过对其金相组织观察以及成分偏析分析,发现振动工艺相对传统铸造工艺,对铸件晶粒组织的细化,成分偏析的改善,以及力学性能的提升均起到了积极作用,且有效改善了传统铸造工艺中存在的缩孔,缩松、裂纹等宏观缺陷。考虑振动过程中薄带是否与结晶辊脱离等因素,提出了振动工艺参数的选取条件,选取13组不同振动参数进行振动铸造正交对比实验,通过实验结果对比,验证了参数选取条件的合理性。通过对不同振频、振幅工艺条件下所铸铸件的实验结果对比,发现在振频25Hz以内,振幅0.5mm以内,随着参数值提高,形核率不断提升,中心等轴晶区不断扩大,金属内部不同低量元素的正常偏析以及比重偏析现象逐步得到改善,但振幅超过0.5mm以后,改善效果不再明显,甚至恶化了金属组织。
[Abstract]:As a technical means of near-end forming casting and rolling, twin-roll thin strip casting has the advantages of low energy consumption and high efficiency compared with traditional continuous casting. However, some traditional double-roll casting strip billets have uneven microstructure and coarse grain size. The mechanical properties of materials will be reduced because of the developed columnar crystal and the serious segregation of composition. In view of these defects, the vibrating double-roll strip casting mill is based on the traditional twin-roll strip casting technology. The flow field and temperature field were changed by applying the exciting source on the single side crystal roller, and the microstructure was refined. In this paper, the effect of this vibration process on the metal structure was studied experimentally. The vibrating double-roll strip casting mill was used as the vibration test platform. The experiment scheme of vibration casting was designed, and the design, processing, assembly and debugging of the experimental equipment were completed. The experimental results of vibration casting were compared with those of conventional casting technology. Through the comparative analysis of the rapid cooling and vibration free casting technology, the microstructure of the casting was observed and the composition segregation was analyzed. It was found that the vibration process was more precise than the traditional casting process to refine the grain structure of the casting. The improvement of composition segregation and the improvement of mechanical properties all played a positive role, and effectively improved the shrinkage and porosity in the traditional casting process. Considering whether the strip is separated from the crystal roll during vibration, the selection conditions of vibration parameters are put forward, and 13 groups of different vibration parameters are selected to carry out the orthogonal contrast experiment of vibration casting. Through the comparison of the experimental results, the rationality of the parameter selection conditions is verified. By comparing the experimental results of casting castings with different vibration frequency and amplitude, it is found that the vibration frequency is less than 25 Hz. Within 0.5 mm amplitude, with the increase of parameter value, the nucleation rate increases, the central equiaxed crystal region expands continuously, and the normal segregation and specific gravity segregation of different low-volume elements in the metal are gradually improved. However, when the amplitude exceeds 0.5 mm, the improvement effect is no longer obvious, and even the metal structure is deteriorated.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG24

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