Computer simulation of solidification processes—The evolution of a technology

The historical development of solidification modeling is traced, as applied to solidification processing. Clearly, the growth of this technology followed the computer explosion, particularly with regard to hardware. However, universities and government laboratories made substantial contributions in the software area, particularly in removing roadblocks to the further development of the technology and by creative examples. The commercial software houses have utilized these leading-edge developments, a practice continued and expanding today. Heat-transfer analyses by computer were initiated by utilizing the analog computer, which appeared to be a competing technology, but by the early 1960s, the digital computer had become the winner in larger-scale computation. A number of benchmark achievements followed over the next several decades. The evolution of this technology is documented, including predictions of solidification microstructure and resulting material properties. Future developments are projected. This lecture was presented to honor Edward DeMille Campbell (University of Michigan, Class of 1886), born in 1863, who was appointed Assistant Professor of Metallurgy in 1890. Dr. Campbell brought a strong interest in the study of the constitution of metals and alloys to the University of Michigan. In 1892, during a study of the composition of steel, he lost his eyesight in a laboratory explosion. Within five days, he returned to the University, and resumed his teaching and research. Over the next 30 years, he published 72 research papers, and developed a laboratory course in metallography. In 1924, working under the direction of Professor Campbell, William Fink discovered a new, tetragonal form of iron (martensite) in the first significant application of a new tool, X-ray diffraction, to physical metallurgy. It was these experiments that established the beginning of a strong tradition in physical metallurgy at the University of Michigan. In 1898, Campbell led the effort to establish Chemical Engineering at Michigan, becoming Professor of Chemical Engineering and Analytical Chemistry in 1902. In 1914, Campbell was appointed Director of the University’s Chemical Laboratory and Professor of Chemistry. Following his death in 1925, the American Society for Metals established this annual award in his name. The Edward DeMille Campbell Memorial Lecture was established in 1926 as an annual lecture in memory of and in recognition of the outstanding scientific contributions to the metallurgical profession by a distinguished educator who was blind for all but two years of his professional life. It recognizes demonstrated ability in metallurgical science and engineering. Robert D. Pehlke studied at the University of Michigan, B.S.E. (Met. Eng.) 1955, Massachusetts Institute of Technology, S.M. (Met.) 1958, and Sc.D. (Met.) 1960, and at the Technical Institute, Aachen, as a Fulbright Fellow, 1956–57. He joined the faculty of the University of Michigan as Assistant Professor in February 1960, and was appointed Associate Professor in June 1963 and full Professor in June 1968. In May 1973, he was named Chairman of the Department of Materials and Metallurgical Engineering. In June 1978 and 1983, he was reappointed Department Chairman and served until June 1984. In 1994, he was Visiting Professor at Tohoku University (Sendai, Japan). He is a member of AIME and ASM, and has served on numerous divisional and award committees within these societies. He has served on the Technical Divisions Board (1982–84), as Secretary of the ASM Academy for Metals and Materials Committee, and in 1976 was named a Fellow of the Society. In 1964, he co-edited the ASM seminar volume on Computers in Metallurgy. He has served as Chairman of the Process Technology Division and as a Director of the ISS-AIME. In 1980, he was named a Distinguished Life Member of the ISS. In 1976, he received the Science Award Gold Medal of the Extractive Metallurgy Division of TMS-AIME. In 1983, he was named a Fellow of TMS. He was chairman of the former AIME-ISS Division Publications Committee. He served as chairman of the Editorial Board for the AIME Monograph Series on Oxygen Steelmaking. In 1980, he presented the Howe Memorial Lecture on “Steelmaking—The Jet Age.” In 1991–92, he was the Krumb Lecturer of the Metallurgical Society. In 1980, he was named a Case Institute Centennial Scholar and the Van Horn Distinguished Lecturer at Case Western Reserve University. He has lectured widely internationally, and at technical conferences, universities, corporations, and technical society chapters, including presenting a number of keynote, invited, and honorary lectures. He was National President of Alpha Sigma Mu and a member of Tau Beta Pi, Sigma Xi, and the New York Academy of Sciences. He is also a member of the American Society for Engineering Education and the American Foundry Society. He has held memberships in the Iron and Steel Institute of London, the Iron and Steel Institute of Japan, and the Verein Deutscher Eisenhuttenleute. He is a registered professional engineer in the State of Michigan. Dr. Pehlke has served as Foundry Educational Foundation Professor at The University of Michigan for 17 years. Professor Pehlke has authored or co-authored over 300 publications, including editing, authoring, or co-authoring 11 books. His text Unit Processes of Extractive Metallurgy has been widely used throughout the world. He co-authored Continuous Casting—Design and Operations, which is Volume 4 of the ISS-AIME series. He has won seven American Foundry Society Best Paper awards. In 1963, Dr. Pehlke published an ASM pioneering paper first describing computer modeling of continuous casting of steel. In 1964, he continued this work in conjunction with McLouth Steel Corporation, which had just installed the first slab casting machine for steel in the United States. In 1968, he, with the support of the Heat Transfer Committee of the American Foundry Society, initiated the first university research program in North America on computer modeling of the solidification of shaped castings. His early professional employment included three summers each with General Motors Research Laboratories and the Ford Scientific Laboratory. He has consulted extensively on a wide range of metallurgical subjects, principally with ferrous and nonferrous metal producers and their suppliers. His research has covered a broad range of metallurgical topics with an emphasis on high-temperature physical chemistry of metallurgical systems, modeling of solidification of metals, and computer applications in metallurgy.     

Computer simulation of solidification processes—The evolution of a technology

The historical development of solidification modeling is traced, as applied to solidification processing. Clearly, the growth of this technology followed the computer explosion, particularly with regard to hardware. However, universities and government laboratories made substantial contributions in the software area, particularly in removing roadblocks to the further development of the technology and by creative examples. The commercial software houses have utilized these leading-edge developments, a practice continued and expanding today. Heat-transfer analyses by computer were initiated by utilizing the analog computer, which appeared to be a competing technology, but by the early 1960s, the digital computer had become the winner in larger-scale computation. A number of benchmark achievements followed over the next several decades. The evolution of this technology is documented, including predictions of solidification microstructure and resulting material properties. Future developments are projected. This lecture was presented to honor Edward DeMille Campbell (University of Michigan, Class of 1886), born in 1863, who was appointed Assistant Professor of Metallurgy in 1890. Dr. Campbell brought a strong interest in the study of the constitution of metals and alloys to the University of Michigan. In 1892, during a study of the composition of steel, he lost his eyesight in a laboratory explosion. Within five days, he returned to the University, and resumed his teaching and research. Over the next 30 years, he published 72 research papers, and developed a laboratory course in metallography. In 1924, working under the direction of Professor Campbell, William Fink discovered a new, tetragonal form of iron (martensite) in the first significant application of a new tool, X-ray diffraction, to physical metallurgy. It was these experiments that established the beginning of a strong tradition in physical metallurgy at the University of Michigan. In 1898, Campbell led the effort to establish Chemical Engineering at Michigan, becoming Professor of Chemical Engineering and Analytical Chemistry in 1902. In 1914, Campbell was appointed Director of the University’s Chemical Laboratory and Professor of Chemistry. Following his death in 1925, the American Society for Metals established this annual award in his name. The Edward DeMille Campbell Memorial Lecture was established in 1926 as an annual lecture in memory of and in recognition of the outstanding scientific contributions to the metallurgical profession by a distinguished educator who was blind for all but two years of his professional life. It recognizes demonstrated ability in metallurgical science and engineering. Robert D. Pehlke studied at the University of Michigan, B.S.E. (Met. Eng.) 1955, Massachusetts Institute of Technology, S.M. (Met.) 1958, and Sc.D. (Met.) 1960, and at the Technical Institute, Aachen, as a Fulbright Fellow, 1956–57. He joined the faculty of the University of Michigan as Assistant Professor in February 1960, and was appointed Associate Professor in June 1963 and full Professor in June 1968. In May 1973, he was named Chairman of the Department of Materials and Metallurgical Engineering. In June 1978 and 1983, he was reappointed Department Chairman and served until June 1984. In 1994, he was Visiting Professor at Tohoku University (Sendai, Japan). He is a member of AIME and ASM, and has served on numerous divisional and award committees within these societies. He has served on the Technical Divisions Board (1982–84), as Secretary of the ASM Academy for Metals and Materials Committee, and in 1976 was named a Fellow of the Society. In 1964, he co-edited the ASM seminar volume on Computers in Metallurgy. He has served as Chairman of the Process Technology Division and as a Director of the ISS-AIME. In 1980, he was named a Distinguished Life Member of the ISS. In 1976, he received the Science Award Gold Medal of the Extractive Metallurgy Division of TMS-AIME. In 1983, he was named a Fellow of TMS. He was chairman of the former AIME-ISS Division Publications Committee. He served as chairman of the Editorial Board for the AIME Monograph Series on Oxygen Steelmaking. In 1980, he presented the Howe Memorial Lecture on “Steelmaking—The Jet Age.” In 1991–92, he was the Krumb Lecturer of the Metallurgical Society. In 1980, he was named a Case Institute Centennial Scholar and the Van Horn Distinguished Lecturer at Case Western Reserve University. He has lectured widely internationally, and at technical conferences, universities, corporations, and technical society chapters, including presenting a number of keynote, invited, and honorary lectures. He was National President of Alpha Sigma Mu and a member of Tau Beta Pi, Sigma Xi, and the New York Academy of Sciences. He is also a member of the American Society for Engineering Education and the American Foundry Society. He has held memberships in the Iron and Steel Institute of London, the Iron and Steel Institute of Japan, and the Verein Deutscher Eisenhuttenleute. He is a registered professional engineer in the State of Michigan. Dr. Pehlke has served as Foundry Educational Foundation Professor at The University of Michigan for 17 years. Professor Pehlke has authored or co-authored over 300 publications, including editing, authoring, or co-authoring 11 books. His text Unit Processes of Extractive Metallurgy has been widely used throughout the world. He co-authored Continuous Casting—Design and Operations, which is Volume 4 of the ISS-AIME series. He has won seven American Foundry Society Best Paper awards. In 1963, Dr. Pehlke published an ASM pioneering paper first describing computer modeling of continuous casting of steel. In 1964, he continued this work in conjunction with McLouth Steel Corporation, which had just installed the first slab casting machine for steel in the United States. In 1968, he, with the support of the Heat Transfer Committee of the American Foundry Society, initiated the first university research program in North America on computer modeling of the solidification of shaped castings. His early professional employment included three summers each with General Motors Research Laboratories and the Ford Scientific Laboratory. He has consulted extensively on a wide range of metallurgical subjects, principally with ferrous and nonferrous metal producers and their suppliers. His research has covered a broad range of metallurgical topics with an emphasis on high-temperature physical chemistry of metallurgical systems, modeling of solidification of metals, and computer applications in metallurgy.     

3-D simulation of metal forming processes with automatic mesh generation

The numerical simulation of industrial metal forming processes requires robust and feasible solution methods. In this context, any solution procedure must be able to handle three-dimensional problems with general contact conditions and severe deformations. The latter condition necessitates automatic mesh-generation abilities. At the same time, the simulation tool must be economical and user-friendly. In this paper, a solution procedure is introduced which is able to perform the numerical simulation of complex industrial metal forming processes without any interference. The procedure is based on the rigid-plastic finite element method and is primarily suited to the analysis of bulk metal-forming processes. To ensure a real automatic simulation, the numerical procedure is made robust by using Euler time integration, a Newton-Raphson solver which is coupled with a direct iteration solver, a linear contact algorithm and, finally, a completely automatic hexahedral mesh generation scheme. The method is implemented in the ANSI-C programming language. To demonstrate the effectiveness of the method an industrial application has been simulated: A spider produced from a cylindrical initial workpiece by cold radial-extrusion.     

连铸过程中夹杂物去除数值模拟研究现状

摘要：随着钢材质量要求的提高,连铸过程中夹杂物的控制已经成为了钢铁企业的重要课题。受限于现实条件及连铸过程的复杂性,数值模拟技术成为了研究连铸过程夹杂物行为的重要手段之一。结合数值模拟研究现状介绍了中间包内电磁技术、流动控制元件和底吹氩技术对夹杂物上浮去除的积极作用,发现夹杂物性质及非等温条件对夹杂物行为的影响还较少被研究;探讨了优化浸入式水口（SEN）和合理应用电磁技术对结晶器内夹杂物去除的重要影响,当前结晶器内的夹杂物模拟研究正在向微观层面进行过渡。连铸过程中夹杂物行为的数值模拟研究随着计算机技术的发展和数学模型的完善也在不断进步。     

服务概念的多层次理解

服务,作为服务学科的核心概念,能够被正确理解十分必要.相关文献回顾表明,学者们对服务概念的解释存在巨大差异,主要原因是他们的行业背景和学科背景不同,因而侧重点不同.从服务产生的根源出发,构建了包含服务行为、服务产品、服务组织、服务产业及服务社会的多层次服务概念体系,并基于以上五个层次厘清了服务的特征.     

Physical parameters and boundary conditions for the numerical simulation of hot forming processes

Exact simulation of hot-forming processes using the finite element method requires the most precise possible specification of the material parameters and physical boundary conditions prevailing in each case. The report presents a method to supply all the necessary data. New experimental concepts have been developed and applied, particularly for the more complex boundary conditions, which are virtually undocumented in literature. These techniques permit analysis of the real workpiece/interlayer/die combination, supplying reliable data for an FEM simulation.     

Using the method of thermodynamic simulation for a description of processes of powder metallurgy

The methodology of the thermodynamic simulation of physicochemical transformations in processes of powder metallurgy (such as obtaining powders via dispersing the iron-carbon melts with water, air, and their mixture; the reduction of the crude powder in an atmosphere of hydrogen and endogas; and sintering of the powder material in nitrogen with the addition of 5% hydrogen and in vacuum) is described. The results of a calculation of possible compositions of the condensed and gas phases of the listed processes are described. These data are used in the development of technology for obtaining powder and grit low-doped with vanadium and chromium.     

不同强度岩石的破坏过程及声发射数值模拟

采用FLAC模拟了初始内聚力及内摩擦角对具有随机材料缺陷单轴平面应变压缩岩样破坏过程及声发射的影响;采用编写的若干FISH函数规定随机缺陷及统计发生破坏的单元数目.密实的岩石服从莫尔-库仑剪破坏与拉破坏复合的破坏准则,破坏之后呈现应变软化-理想塑性行为;缺陷在破坏之后经历理想塑性行为.随着密实岩石强度参数的提高,从应力峰值到残余应力的应力降、轴向应变增量提高,贯通试样的剪切带出现滞后,试样内部最终发生破坏的单元数降低.对于密实岩石强度参数高的试样,缺陷全部发生破坏之后,密实岩石没有立即发生破坏;应力峰值被达到之后,破坏的单元数增长不大.在加载过程中,声发射数有显著增加的三个区段.区段1、2及区段3的绝大部分位于峰前.在区段3的峰前阶段,声发射数的增加源于缺陷的长大、聚结、传播和竞争.强度参数越高,区段3越长,区段3的峰值越低.这表明当密实岩石的强度参数较高时,密实岩石单元破坏相继发生,破坏过程持续得较长.     

7055铝合金多级均匀化工艺研究

采用中频炉熔炼7055铝合金,用光学显微镜、扫描电镜、能谱仪和万能拉伸机等方法研究多级均匀化工艺对7055铝合金显微组织及力学性能的影响。结果表明：未经均匀化处理的7055铝合金铸锭存在着严重的组织偏析,合金经470℃×30 h单极均匀化处理后,晶界上的非平衡相有所减少,已形成不连续分布,成分偏析得到改善;在单极均匀化基础上增加410℃×4 h的中间保温,均匀化效果更好,非平衡相的溶解数量增多,晶界更为平直,且形状规整;而经250℃×4 h＋410℃×4 h＋470℃×30 h三级均匀化处理后,消除了铸锭晶界上的非平衡凝固共晶组织,晶界呈线条状。经时效处理后,其力学性能较优。