This article explains cooling mechanisms involving saltwater solutions used as quenchants. The analyses of cooling power include studies of cooling curves, heat-transfer coefficients, and cooling rates. The influence of other bath parameters, such as temperature and agitation, is also discussed. The article discusses solute additions and several factors impacting quenching.

This article presents the modes of heat transfer and the stages of cooling during quenching. It provides an overview on the wetting process and then focuses on the evaluation of heat transfer during quenching. It also presents the challenges of thermal process evaluation based on an inverse heat conduction analysis. The article contains a compilation of best practice examples on heat transfer evaluation, which are intended to represent the practical aspects and applicability of the methods aiming the prediction of heat-transfer coefficients.

Spray quenching (or jet impingement) is the most common technique employed to improve the uniformity of heat removal and break the vapor layer, allowing for a high cooling rate to be achieved. This article presents the heat transfer characteristics of quenching a hot surface, which can be expressed by the boiling and quench curve. It discusses three major spray parameters that have a substantial role in the quantification of spray cooling performance: droplet size, droplet velocity, and volumetric flux. The article also presents the available models and correlations to predict the cooling rate in spray quenching of hot surfaces during different boiling phases. It then discusses the effect of surface roughness on spray cooling performance.

Thermal analysis is used to analyze solidification processes by recording the temperature as a function of time during cooling or heating of a metal or alloy to or from a temperature above its melting point. This article describes the use of cooling curves for analyzing a solidification process, such as the solidification temperature, structure analysis, fraction of phases and heat of fusion with focus on solidification of cast iron, and the use of cooling curves to control and adjust the casting conditions. It discusses deviations from equilibrium that occur due to kinetic effects during solidification. The article also illustrates the evaluation of fraction of solid formed during the precipitation of austenite from heat balance.

This article describes different methods by which the composition of cast iron can be analyzed. It provides particular emphasis on the methods for evaluating the graphitization potential of a melt with prescribed limits on carbon, silicon, and alloying elements. The article discusses the effect of cooling rate on the graphitization of a given composition by chill and wedge tests. Thermal analysis of cooling curves gives excellent information about the solidification and subsequent cooling of cast iron alloys. The article presents some applications of the cooling curve analysis and explains the evaluation of carbon-silicon contents, graphite shape, graphite nucleation, and contraction-expansion balance. It illustrates the use of an immersion steel sampling device for compacted graphite iron production and provides information on the ferrite-pearlite ratio in ductile iron.

In cast iron, residual stresses normally arise due to hindered thermal contraction, meaning that they are associated with the presence of constraints that prevent the natural, free volumetric variation of the material upon solid-state cooling. This article explains their mechanism of formation by introducing the scalar relation, known as the additive strain decomposition. The main factors influencing casting deformation are volume changes during solidification and cooling, phase transformations, alloy composition, thermal gradients, casting geometry, and mold stability. The article reviews the dimensional stability in cast iron and discusses macroscopic and microscopic stresses in cast iron.

Solidification processing is one of the oldest manufacturing processes, because it is the principal component of metal casting processing. This article discusses the fundamentals of solidification of cast iron. Undercooling is a basic condition required for solidification. The article describes various undercooling methods, including kinetic undercooling, thermal undercooling, constitutional undercooling, and pressure undercooling. For solidification to occur, nuclei must form in the liquid. The article discusses the various types of nucleation: homogeneous nucleation, heterogeneous nucleation, and dynamic nucleation. It reviews the classification of eutectics based on their growth mechanism: cooperative growth and divorced growth. The article concludes with a discussion on the solidification structures of peritectics.

Sintering atmosphere protects metal parts from the effects of contact with air and provides sufficient conduction and convection for uniform heat transfer to ensure even heating or cooling within various furnace sections, such as preparation, sintering, initial cooling, and final cooling sections. This article provides information on the different zones of these furnace sections. It describes the types of atmospheres used in sintering, namely, endothermic gas, exothermic gas, dissociated ammonia, hydrogen, and vacuum. The article concludes with a discussion on the furnace zoning concept and the problems that arise when these atmospheres are not controlled.

This article focuses on the cooling process and related transformation behavior of steel wires during patenting to identify a physical metallurgical basis for the development of nontoxic alternatives to molten lead for wire patenting. It describes the materials required, the procedures, and the results of cooling curve analysis. The article schematically summarizes the cooling behaviors of the various cooling media and the microstructure of the pearlite transformation in a lead bath.

Cooling towers are designed to remove heat from water in an induction system and dissipate it into the atmosphere. This article provides information on closed-loop recirculating water systems of an induction system to cool the power supply. It focuses on various types of cooling towers, namely, air-cooled heat exchangers, air-cooled heat exchangers with trim cooler, closed-circuit evaporative cooling towers, and open evaporative cooling towers. The article discusses the importance of their placement or positioning to reduce the chances of air recirculation, and concludes with a discussion on refrigerant chillers.

Magnetic flux controllers are materials other than the copper coil that are used in induction systems to alter the flow of the magnetic field. This article describes the effects of magnetic flux controllers on common coil styles, namely, outer diameter coils, inner diameter coils, and linear coils. It provides information on the role of magnetic flux controllers for whole-body and local area mass-heating applications, continuous induction tube welding, seam-annealing inductors, and various induction melting systems, namely, channel-type, crucible-type, and cold crucible systems. The article also describes the benefits of the flux controllers for induction heat treating processes such as single-shot and scanning.

This article provides information on single-shot and scanning, the two types of induction heat treating processes that are based on whether the induction coil is moving relative to the part during the heating process. It describes the effect of the frequency of induction heating current on the induction coil and process design, and the control of heating in different areas of the inductor part. The article reviews three main tools for adjustment of coil design and fabrication: coupling gap, coil copper profile, and magnetic flux controllers. It examines the method of holding a part and presenting it to the inductor during the initial inductor design. The article provides information on coil leads/busswork and contacts that mechanically and electrically connect the induction coil head to the power supply. It concludes with a discussion on flux and oxide removal, leak and flow checking, silver plating, and electrical parameter measurement.

Normalizing of steel is a heat treating process that is often considered from both thermal processing and microstructural standpoints. In terms of thermal processing, normalizing is defined as heating of a ferrous alloy to a suitable temperature above the transformation range and then cooling it in air to a temperature substantially below the transformation range. This article provides information on the normalizing of carbon and alloy steels, and discusses the processes involved and the furnaces used in normalizing of steel forgings, bar and tubular products, and castings. It contains tables that list the typical normalizing temperatures for standard carbon and alloy steels and typical mechanical properties of selected carbon and alloy steels in hot-rolled, normalized, and annealed conditions.

This article, with the aid of illustrations and curves, describes an experiment used to understand the cooling characteristics and transformation behavior of steel wires during patenting. The two aqueous polymer quenchants used as alternatives for lead baths, are carboxymethyl cellulose and polyvinyl alcohol. A small amount of polymer additive in spraying could modify the physical properties of the spray medium and improve atomizing status. The concentration-fog flux effect further improves the flexibility of spraying and makes it easier to control the cooling process.

This article provides an overview of common quenching media, the factors involved in the mechanism of quenching, and process variables, namely, surface condition, mass and section size of the workpiece, and flow rate of the quenching liquid. It describes the methods of quenchant characterization using hardening-power and cooling-power tests. The article discusses the fundamentals involved in heat-transfer coefficient and heat flux of quenching processes. This discussion is followed by various actual examples of applications of these methods using simplified equations. Quenchant evaluation, classification, selection, and maintenance are reviewed in detail. The article addresses the various reasons for quench oil variability and complications due to aging and contamination.

This article reviews the fundamental solidification concepts for understanding microstructural evolution in fusion welds. The common concepts, namely, nucleation, competitive grain growth, constitutional supercooling, solute redistribution, and rapid solidification, depend on the solidification parameters during welding, are discussed. The article discusses important solidification parameters, including temperature gradient, solid/liquid interface growth rate, and cooling rate.

The finished product, after fusion welding, may contain physical discontinuities due to excessively rapid solidification, adverse microstructures due to inappropriate cooling, or residual stress and distortion due to the existence of incompatible plastic strains. To analyze these problems, this article presents an analysis of the welding heat flow, with focus on the fusion welding process. It discusses the analytical heat-flow solutions and their practical applications. The article concludes with a description of the effects of material property and welding condition on the temperature distribution of weldments.

This article focuses on the axisymmetric 2.5-dimensional approach used in metal powder injection molding (PIM) simulations. It describes three stages of PIM simulations: filling, packing, and cooling. The article discusses the process features of numerical simulation of PIM, such as filling and packing analysis, cooling analysis, and coupled analysis between filling, packing, and cooling stages. It explains the experimental material properties and verification for filling, packing, and cooling stages in the PIM simulations. The article presents simulation results from some of the 2.5-dimensional examples to demonstrate the usefulness of the computer-aided engineering analysis and optimization capability of the PIM process.

This article describes the applications, advantages, and disadvantages of three centrifugal casting processes as well as the equipment used. These processes are true centrifugal casting, semicentrifugal casting, and centrifuge mold casting. The article discusses the cooling, inoculation, fluxing, and extraction of castings. It reviews mold heating and coating techniques as well as the various molds used. The three most common defects observed in centrifugal castings are also discussed. The article concludes with information on the applications of centrifugal casting in investment casting and combustion synthesis as well as spin casting.