【作者】 康纪龙；

【导师】 曹志强； 刘庆；

【作者基本信息】 大连理工大学 ， 材料工程， 2012， 硕士

【摘要】 铅白铜和铅黄铜具有良好的物理性能和切削性能,并且耐腐蚀性能优异,加工成型性好,被广泛的用于制造仪器仪表、船用零件和医疗器械等。近年来随着工业及国民经济的迅速发展,对它们需求数量日益增多,并对其质量和生产效率也提出了越来越高的要求。在铜合金的水平连续铸造技术中施加电磁场可以消除铸坯凝固组织粗大且周向分布不均匀、表面质量差等缺陷。本文利用水平电磁连铸技术进行了铅白铜及铅黄铜的生产试验,通过试验过程的工艺参数匹配及优化,获得性能及组织优异的铸坯,为生产高质量的铜合金铸坯提供技术支撑。首先,进行了圆铜坯水平连铸的水模拟实验。根据相似原理,利用流动的水来模拟铜液的流动,研究水平连铸结晶器结构对铜液流动的影响,为优化结晶器结构提供依据。实验结果表明,采用结晶器侧壁四孔倾斜结构更有利于消除比重偏析,均匀成分分布,从而更有利于产品质量提高。另外,关于水平连铸圆铜坯凝固过程热流耦合场的模拟表明,拉坯速度对铸坯温度场影响较大,浇注温度的影响相对较小。电磁场对圆铜坯流场及温度场的影响是：施加磁场后,熔体流动出现紊流,流动速度随着电源频率、强度的增加而增加；并且液芯长度减小,结晶器出口铸坯截面的液芯直径减小。但是,随着电磁场频率的增加,集肤效应越来越明显。通过工艺实验改善了圆铜坯水平连铸结晶器的结构,研究了工艺参数对铸坯组织及合金元素偏析的影响。经过大量的实验,工艺参数的合理设置,进行水平电磁连续铸造,得到横截面直径为Φ200mm的细晶组织铸坯。结果表明,电磁场使铸坯宏观凝固组织显著细化,微观凝固组织呈现一定的均匀化。并有效抑制了Pb元素的偏析,改变了富Pb相的分布。对于铅白铜合金,在输入电流强度为160A,磁场频率为30Hz,一次冷却水流量为6-8m3/min,铸造速度为32.24mm/min,浇注温度为980℃时获得组织优异的铸坯；对于铅黄铜在输入电流强度为100A,磁场频率为30Hz,一次冷却水流量为6-8m3/min,二次冷却水流量为3-4m3/min,铸造速度为94mm/min,浇注温度为890-930℃时获得组织优异的铸坯。此即为最佳工艺参数。更多还原

【Abstract】 Lead cupronickel and Lead brass alloy have excellent physical and cutting properties, and corrosion resistance. They are easy to processing production, are widely used to produce instruments, medical equipment and marine parts, etc. In recent years, with the development of industry and national economy, the needs of high quality copper and copper alloys and the requirements for the high production efficiency increase quickly. Horizontal electromagnetic continuous casting can eliminate many problems of billets such as poor surface quality, many casting defects> and coarse grains in solidification structure as well as poor uniformity of structure in the circumferential direction. In this paper, we focus on the study of application of electromagnetic field in the horizontal continuous casting, then the parameters of horizontal electromagnetic continuous casting of copper alloy billets are optimized to provides a chance for producing high quality copper and copper alloy billets.First of all, horizontal continuous casting of round copper billet is simulated with water experiment. According to the similar principles, the use of the water flow to simulate the flow of liquid copper, research the effect of crystallizer structure on the copper flow, and to optimize it. The results show that crystallizer with four inclined holes on side wall structure is better to eliminate the proportion of segregation, homogenize composition distribution and useful for improving product quality. In addition, the simulation results about heat-low coupling field of copper solidification process under horizontal continuous casting show that the effect of casting speed is bigger while casting temperature is relatively minor. The effect of electromagnetic field on round copper billet’s flow field and temperature field shows that the electromagnetic field obviously changes the flow pattern of the melt in billet. The flow rate of the melt increases with the increase of electromagnetic frequency and intensity. And the liquid core length and diameter of crystallizer"s longitudinal section is decreased. But, with the increase of the electromagnetic frequency, skin effect becomes more and more obvious.The technology of horizontal electromagnetic continuous casting of copper billets is applied to the industrial production. The problems of designing the structure of the crystallizer and the research on the effect of process parameters on microstructure and the alloy element segregation are solved. The experiments of horizontal electromagnetic continuous casting of (p200mm copper billets were produced after vast of experimental exploration and experimental parameters being optimized. The results show that the macrostructures are greatly refined and the microstructures is well distributed in certain extent. The searesations of Pb is restrained and the distribution of Pb-rich phase is changed with electromagnetic field. For lead cupronickel alloy the optimized parameters are as follws:the current intensity is160A, the current frequency is30Hz, the cooling intensity is6-8m3/min, the casting speed is32.24mm/min> the casting temperature is980oC. For lead brass alloy the optimized parameters are following:the current intensity is100A, the current frequency is30Hz, the first cooling intensity is6-8m3/min, the second cooling intensity is3-4m3/min, the casting speed is94mm/min, the casting temperature is890-930oC.更多还原