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以双辊薄带连续铸轧工艺凝固过程为基础,基于金属凝固的基本原理,并运用现代计算机仿真技术建立了双辊薄带连铸凝固过程的异质形核、修正的枝晶尖端生长动力学、柱状晶向等轴晶生长转变(CET)的解析模型以及基于元胞自动机(CA)的双辊薄带连续铸轧凝固组织的仿真模型,为双辊薄带连续铸轧凝固组织形成的仿真模拟奠定了基础,同时利用铝合金双辊薄带连续铸轧组织凝固过程验证了数学模拟的可行性。结果表明:可用建立的数学模型模拟预测铸轧工艺参数对双辊连续铸轧薄带凝固组织的影响。 相似文献
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在研究双辊连铸铝合金薄带工艺凝固过程的基础上,基于金属凝固的基本原理,建立双辊连铸铝合金薄带凝固的异质形核、枝晶尖端的生长动力学(KGT)、柱状晶向等轴晶生长的转变(CET)的解析模型,同时建立基于元胞自动机(CA)的双辊连铸铝合金薄带凝固组织的仿真模型,为双辊连铸薄带凝固组织形成的仿真模拟奠定基础,从而为双辊薄带连铸工艺提供一定的理论指导。同时利用铝合金双辊薄带连续铸轧组织凝固过程验证了数学模拟的可行性。 相似文献
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基于枝晶生长的基本传输过程和元胞自动机(Cellular Automaton,简称CA)-有限元(Finite Element,简称FE)模型基本原理,建立了适应双辊连续铸轧纯铝薄带工艺特点的凝固过程形核和晶体生长的数学模型。模型耦合了宏观温度场和微观组织模拟计算,考虑了溶质扩散、曲率过冷和潜热释放等重要因素的影响,能够模拟凝固过程中枝晶生长的形态。应用本模型对双辊连续铸轧纯铝薄带凝固过程中等轴晶生长、等轴晶多晶粒生长及柱状晶生长、柱状晶向等轴晶演化进行模拟并与实验结果进行对比,模拟结果与实验结果吻合较好 相似文献
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《特种铸造及有色合金》2016,(2)
采用上方侧注式双辊铸轧工艺制备了1050铝铸轧薄带,并观察了薄带金相组织。结果表明,1050铸轧薄带表面质量良好;薄带厚度随带坯长度的增加而先增加后趋于稳定。金相组织观察表明,上方侧注式双辊铸轧薄带上辊侧与下辊侧组织存在明显差异。上辊侧为等轴生长的凝固组织,下辊侧为轧制变形组织,且中间存在一条分界线,是由于轧制作用改善冷却条件所产生的。 相似文献
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采用元胞自动机-有限单元法模型对双辊连续铸轧纯铝凝固组织进行了模拟。形核模型采用基于高斯分布的连续性形核模型,辊面和熔体内部形核采用两种形核分布函数;枝晶尖端生长速度和局部过冷度的关系采用修正的KGT模型。并研究了工艺参数和凝固参数对凝固晶粒组织的影响。结果表明,所建立的数学模型能够合理描述晶粒沿任意角度生长的过程,对温度场、溶质场和微观组织形貌的模拟计算结果合理。随着辊面传热系数的增大,薄带柱状晶宽度增加;随着体积形核密度的增大,薄带柱状晶宽度减小且晶粒组织变得细小均匀。 相似文献
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采用楔形布流器,把整个双辊薄带铸轧熔池处理成钢液和空气的自由表面两相流,建立了熔池内钢液凝固传热的三维流热耦合仿真模型,进而对布流器侧水口倾角对熔池内钢液的凝固及温度分布的影响进行了研究。结果表明,当楔形布流器的侧水口倾角为0°时,熔池内钢液的凝固结束点(kiss点)高度适中,此时,双辊对薄带坯的轧制力也比较适宜,铸带宽度方向上温差较小,可有效地减少或避免薄带出现横裂纹和纵裂纹,获得较好的铸带质量。研究结果对双辊薄带连铸布流器水口倾角的设计提供了理论依据。 相似文献
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Nucleation and growth model based on Cellular Automation(CA) incorporated with macro heat transfer calculation was presented to simulate the microstructure of aluminum twin-roll casting. The dynamics model of dendrite tip (KGT model) was amended in view of characteristics of aluminum twin-roll casting. Through the numerical simulation on solidification structure under different casting speeds, it can be seen that when the casting speed is 1.3 m/min, that is, under conditions of conventional roll casting, coarse columnar grains dominate the solidification structure, and equiaxed grains exist in the center of aluminum strip. When the casting speed continuously increases to 8 m/min, that is, under the conditions of thin-gauge high-speed casting, columnar grains in solidification structure all convert into equiaxed grains. Experimental and numerical results agree well. 相似文献
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《Intermetallics》2006,14(8-9):987-993
Twin-roll strip casting was utilized to fabricate the sheet products of Zr- and Cu-base bulk amorphous alloys with quite different glass forming abilities (GFAs). Simulation of the solidification behavior of the these amorphous forming alloys during twin-roll strip casting shows that suitable cooling rate can be achieved by twin-roll strip casting to form amorphous structure through the thickness of sheet. Optimum twin-roll strip casting conditions have been suggested based on the simulation results. Actual twin-roll strip casting shows that both Zr-base alloy with high GFA and Cu-base alloy with much less GFA can be strip cast forming amorphous structure. The results indicate that the twin-roll strip casting is a viable process for continuous fabrication of sheets of bulk amorphous alloys with a wide range of critical cooling rates. 相似文献
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Microstructure and solidification thermal parameters in thin strip continuous casting of a stainless steel 总被引:7,自引:0,他引:7
J. E. Spinelli J. P. Tosetti C. A. Santos J. A. Spim A. Garcia 《Journal of Materials Processing Technology》2004,150(3):255-262
The present work focuses on the relationships between solidification thermal parameters and the dendritic microstructure of an AISI 304 stainless steel solidified both in a strip casting pilot equipment (twin-roll) and in a directional solidification simulator. Experimental studies were conducted with a stainless steel strip casting obtained in a twin-roll continuous caster pilot equipment and in samples solidified in a directional solidification simulator with two different melt superheats. In both cases, the surface of the substrates was similar, with mean surface roughness of about 0.3 μm. After solidification, the specimens were cut at different positions from the metal/mold interface and etched for metallographic examination. An empirical equation from the literature relating secondary dendrite arm spacing and cooling rates was used to demonstrate the similarity of the cooling efficiency. The results have shown that the simulator can be used in the determination of transient metal/mold interface coefficients (hi) and in the preprogramming of the strip casting operational conditions as a function of roll materials and surface roughness. 相似文献
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结合镁合金铸轧工艺特点,分析镁合金板坯铸轧过程中凝固层焊合点位置与板坯缺陷的影响规律;针对板坯厚度、铸轧区长度及铸轧速度等关键参数,简化凝壳径向生长及凝固前沿周向转动过程,确定铸轧速度匹配范围,建立凝固层焊合点位置控制模型,并通过工艺试验对控制模型进行验证.结果表明通过理论模型确定工艺匹配范围,可稳定并优化镁合金铸轧工艺,大幅度降低铸轧板坯宏观缺陷,获得表面光洁、质量良好的镁合金铸轧板坯. 相似文献