Roderick I. L. Guthrie

Bio: Roderick I. L. Guthrie is an academic researcher from McGill University. The author has contributed to research in topics: Tundish & Continuous casting. The author has an hindex of 33, co-authored 179 publications receiving 5500 citations. Previous affiliations of Roderick I. L. Guthrie include York University.

The physical properties of liquid metals

Abstract: Virtually all metals are produced by a process involving a liquid stage. The microstructure, and hence macroscopic properties of the final solid metal, are heavily influenced by the properties of the liquid metal. A proper understanding of liquid metal properties is also essential for the efficient management of refining and alloying processes. This book gives a comprehensive survey of theories, empirical relations and experimental data on the physical properties of liquid metals.

The Physical and Mathematical Modelling of Gas Stirred Ladle Systems

Abstract: Considerable efforts have been made during the past two decades to investigate gas injection operations in steelmaking ladles. Towards these, numerous physical and mathematical model studies embodying aqueous as well as full scale systems have been reported. On the basis of an extensive literature search, a summary, discussion and analysis of these are now presented. For the sake of convenience and clarity of presentation, studies have been categorised into three major groups: (1) physical modelling studies, (2) combined physical and mathematical modelling studies and (3) mathematical modelling studies. In each of these categories, a great number of publications on various phenomena, such as gas-liquid interactions, turbulent fluid flow, mixing, solid-liquid mass transfer, etc. have been reported. Accordingly, and as discussed in the text, considerable improvements have resulted in our understanding of the various gas injection induced phenomena in ladle metallurgy operations. Coupled with these, extensive mathematical modelling studies have also lead to a reasonably accurate framework for carrying out engineering design and process calculations. Nonetheless, some obscurities and uncertainties still remain and these are pointed out, together with those areas where further work is needed.

Coupled turbulent flow, heat, and solute transport in continuous casting processes

Abstract: A fully coupled fluid flow, heat, and solute transport model was developed to analyze turbulent flow, solidification, and evolution of macrosegregation in a continuous billet caster. Transport equations of total mass, momentum, energy, and species for a binary iron-carbon alloy system were solved using a continuum model, wherein the equations are valid for the solid, liquid, and mushy zones in the casting. A modified version of the low-Reynolds numberk-e model was adopted to incorporate turbulence effects on transport processes in the system. A control-volume-based finite-difference procedure was employed to solve the conservation equations associated with appropriate boundary conditions. Because of high nonlinearity in the system of equations, a number of techniques were used to accelerate the convergence process. The effects of the parameters such as casting speed, steel grade, nozzle configuration on flow pattern, solidification profile, and carbon segregation were investigated. From the computed flow pattern, the trajectory of inclusion particles, as well as the density distribution of the particles, was calculated. Some of the computed results were compared with available experimental measurements, and reasonable agreements were obtained.

The Physical and Mathematical Modelling of Continuous Casting Tundish Systems

Abstract: Considerable efforts have been made in academia and industry over the last two decades to fully exploit and enhance the metallurgical performance of continuous casting tundish systems. Towards these goals, numerous physical and mathematical modelling studies embodying both industrial and water model tundishes have been carried out and reported in the literature. Based on an extensive literature search, we now present a summary, discussion and analysis of these. For the sake of convenience and clarity of presentation, the studies have been categorised into three major groups: (1) physical modelling (2) mathematical modelling and (3) combined physical and mathematical modelling. In each of these categories, a great number of publications on various aspects of tundish metallurgy, such as, modelling criteria, turbulent fluid flow, residence time distributions (RTD), inclusion transport and separation, heat loss and temperature drop, grade transition and intermixing, etc. have been reported. These works have lead to considerable improvements in our understanding of the various transport processes (viz, RTD, inclusion float out, thermal energy transport, etc.) associated with tundish operations. Comprehensive and sufficiently reliable mathematical models are also currently available and these also allow one to carry out full scale predictions and useful engineering design and process calculations. None the less, certain obscurities and uncertainties remain. These are reviewed together with suggestions of areas where further research is needed.

Engineering in Process Metallurgy

Abstract: Part 1 An introduction to transport phenomena and properties in metallurgical operations: including Newton's second law of motion Newton's law of viscosity the Chapman-Enskog equation. Part 2 Fluid statics and fluid dynamics: including Navien-Stokes equation flow past spheres at high Reynold's numbers Prandtl's theory of turbulence for boundary layers the Euler (momentum) and Bernoulli equations for inviscid fluids. Part 3 Dimensional analysis and reactor design: including Rayleigh's method of indices Buckingham's "pi" theorem. Part 4 Heat and mass transfer through motionless media: including the "exact" form of Fick's law of diffusion high and low Biot numbers. Part 5 Heat and mass transfer in convective flow systems: including the Lewis-Whitman two-film theory Danckwerts' surface renewal theory. Part 6 Numerical techniques and computer applications: including the Gauss-Siedel point-by-point method. Further reading. Appendices: 1 - nomenclature 2 - units, dimensions and conversion factors 3 - thermodynamic data, worked examples, physical properties, periodic table, error function. Tables. Index. References.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Laser additive manufacturing of metallic components: materials, processes and mechanisms

Abstract: Unlike conventional materials removal methods, additive manufacturing (AM) is based on a novel materials incremental manufacturing philosophy. Additive manufacturing implies layer by layer shaping and consolidation of powder feedstock to arbitrary configurations, normally using a computer controlled laser. The current development focus of AM is to produce complex shaped functional metallic components, including metals, alloys and metal matrix composites (MMCs), to meet demanding requirements from aerospace, defence, automotive and biomedical industries. Laser sintering (LS), laser melting (LM) and laser metal deposition (LMD) are presently regarded as the three most versatile AM processes. Laser based AM processes generally have a complex non-equilibrium physical and chemical metallurgical nature, which is material and process dependent. The influence of material characteristics and processing conditions on metallurgical mechanisms and resultant microstructural and mechanical properties of AM proc...

Computational fluid dynamics of dispersed two-phase flows at high phase fractions

Abstract: This study describes the development and validation of Computational Fluid Dynamics (CFD) methodology for the simulation of dispersed two-phase flows. A two-fluid (Euler-Euler) methodology previously developed at Imperial College is adapted to high phase fractions. It employs averaged mass and momentum conservation equations to describe the time-dependent motion of both phases and, due to the averaging process, requires additional models for the inter-phase momentum transfer and turbulence for closure. The continuous phase turbulence is represented using a two-equation k − ε−turbulence model which contains additional terms to account for the effects of the dispersed on the continuous phase turbulence. The Reynolds stresses of the dispersed phase are calculated by relating them to those of the continuous phase through a turbulence response function. The inter-phase momentum transfer is determined from the instantaneous forces acting on the dispersed phase, comprising drag, lift and virtual mass. These forces are phase fraction dependent and in this work revised modelling is put forward in order to capture the phase fraction dependency of drag and lift. Furthermore, a correlation for the effect of the phase fraction on the turbulence response function is proposed. The revised modelling is based on an extensive survey of the existing literature. The conservation equations are discretised using the finite-volume method and solved in a solution procedure, which is loosely based on the PISO algorithm, adapted to the solution of the two-fluid model. Special techniques are employed to ensure the stability of the procedure when the phase fraction is high or changing rapidely. Finally, assessment of the methodology is made with reference to experimental data for gas-liquid bubbly flow in a sudden enlargement of a circular pipe and in a plane mixing layer. Additionally, Direct Numerical Simulations (DNS) are performed using an interface-capturing methodology in order to gain insight into the dynamics of free rising bubbles, with a view towards use in the longer term as an aid in the development of inter-phase momentum transfer models for the two-fluid methodology. The direct numerical simulation employs the mass and momentum conservation equations in their unaveraged form and the topology of the interface between the two phases is determined as part of the solution. A novel solution procedure, similar to that used for the two-fluid model, is used for the interface-capturing methodology, which allows calculation of air bubbles in water. Two situations are investigated: bubbles rising in a stagnant liquid and in a shear flow. Again, experimental data are used to verify the computational results.

Processing of Bulk Metallic Glass

Abstract: Bulk metallic glass (BMG) formers are multicomponent alloys that vitrify with remarkable ease during solidification. Technological interest in these materials has been generated by their unique properties, which often surpass those of conventional structural materials. The metastable nature of BMGs, however, has imposed a barrier to broad commercial adoption, particularly where the processing requirements of these alloys conflict with conventional metal processing methods. Research on the crystallization of BMG formers has uncovered novel thermoplastic forming (TPF)-based processing opportunities. Unique among metal processing methods, TPF utilizes the dramatic softening exhibited by a BMG as it approaches its glass-transition temperature and decouples the rapid cooling required to form a glass from the forming step. This article reviews crystallization processes in BMG former and summarizes and compares TPF-based processing methods. Finally, an assessment of scientific and technological advancements required for broader commercial utilization of BMGs will be made.