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.

In this article, an in-depth overview of petroleum quenching oils is provided, including oil composition, use, mechanism of the oil quenching processes, oil degradation, toxicology and safety, and quenching bath maintenance.

This article presents the fundamentals and nomenclature of polymer quenchants and provides a detailed discussion on the polymers used for quenching formulation. The article describes the effect of polymer structure on the quenching mechanism. It also presents the factors affecting polymer quenchant performance. The article details the use of polymer quenchants for intensive quenching and then focuses on the wire patenting processes and polymer quenchant analysis. The article presents the application of polymer quenchants for induction hardening. Finally, it provides details on cooling curve analysis of polymer quenchants.

This article focuses on the quenching properties of vegetable and animal oils, including toxicity and biodegradability of vegetable/animal oils. The article provides a detailed discussion on the oxidation of vegetable/animal oils. The addition of antioxidants to stabilize soybean and palm oils is discussed, and the article concludes that substantially better performance is required if vegetable oils are to be effective functional equivalents to petroleum oil formulations. This may be done by selecting different vegetable oil compositions with less unsaturation, by applying genetic modification of soybean seed oils, or by chemically modifying and stabilizing the vegetable oil structure.

This article details investigations on the characterization of various nanofluids as quenchants for industrial heat treatment. It provides a discussion on the preparation, stability, thermophysical properties, and wetting characteristics of nanofluids. The article explains the mechanism of heat transfer in nanofluids and discusses the effect of the deposition of nanoparticles on the probe surface. The article also presents the microstructure and mechanical properties of steel quenched in nanofluids.

This article presents a detailed discussion on the characteristics, types, properties, quenchants, applications, advantages, and disadvantages of various types of quenching: air quenching, water quenching, rinse quenching, time quenching, press quenching, delayed quenching, fluidized-bed quenching, ultrasonic quenching, intercritical quenching, subcritical quenching, ausbay quenching, hot isotactic press quenching, slack quenching, differential quenching, and double quenching.

The fundamental objective of quenching is to preserve, as nearly as possible, a metastable solid solution formed at the solution heat treating temperature, by rapidly cooling to some lower temperature, usually near room temperature. This article provides an overview of the factors used to determine a suitable cooling rate and the appropriate quenching process to develop a suitable cooling rate. It discusses the three distinct stages of quenching: vapor stage, boiling stage, and convection stage. The article reviews the factors that affect the rate of cooling in production operations. It discusses the quenchants that are used in quenching aluminum alloys, namely, hot or cold water and polyalkylene glycol. The article also describes the racking practices for controlling distortion and the level of residual stresses induced during the quench.

Quenching refers to the rapid cooling of metal from the solution treating temperature, typically between 465 and 565 deg C (870 and 1050 deg F) for aluminum alloys. This article provides an overview on the appropriate quenching process and factors used to determine suitable cooling rate. It describes the quench sensitivity and severity of alloys, quench mechanisms and the different types of quenchants used in immersion, spray, and fog quenching. The article provides a detailed description of the quench-factor analysis that mainly includes residual stress and distortion, which can be controlled by proper racking. It concludes with information on agitation and the quench tank system used in the quenching of aluminum alloys.

Quench cracking is a brittle fracture phenomenon, and its occurrence depends not only on the stress changes but also on the mechanical characteristics of metals. Simulation of quenching processes has become possible in the analysis of quench cracking. This article commences with a discussion on the studies conducted to determine the origin of quench cracks, and then describes various test procedures for determining the susceptibility of quench cracking. It provides a description of the brittle fracture in terms of fracture mechanics and fracture toughness of quenched metals, and discusses the effects of impurities, hydrogen, and surface roughness on cracking. The article exemplifies simulation works applied to several successful cracking tests on cylindrical and complex-shaped steel parts.

Successful hardening depends on the hardenability of steel composition, the geometry of parts, the quenching system, and on the heat treating process used. This article provides a brief overview of the computation and use of quench factor analysis (QFA) to quantify as-quenched hardness for carbon and low-alloy steels. As a single-value parameter alternative to Grossmann H-values, QFA is a potential method to qualify a quenching medium or process or to effectively monitor variation of quench severity due to either the quenchant or the system. The article describes the procedures for experimentally determining the quench factors by using a type 304 austenitic stainless steel probe. Typical examples of the utilization of QFA for quenchant characterization are provided. The article also describes the methods for experimentally generating time-temperature-property curves.

This article presents a simple cost/pricing system that is reasonably accurate and could easily be recalculated if the yearly cost of any of the basic cost components change. Using the example of a commercial heat treating facility, the operational details are categorized as atmosphere processes, induction processes, aluminum processes, high-heat processes, and secondary processes. For the purpose of calculating the heat treatment processing cost per hour and the selling price for a piece of equipment, the costs are separated into direct costs, allocated costs, capitalized cost, and general and administrative costs. The article discusses the techniques involved in allocating costs to the group of equipment, and presents a description on the cost analysis of endothermic gas.

The use of gases or molten salts as the quenchant for steel parts is commonly limited to the quenching of high-alloy steel or the carbonizing quenching of low-alloy steel. This article reviews the quenching process of steels with molten metals (quenchant) such as molten lead, molten bismuth, and molten sodium. It also contains tables that list the physical properties of lead, bismuth, sodium, and molten sodium.

Of the various thermal processing methods for steel, heat treating has the greatest overall impact on control of residual stress and on dimensional control. This article provides an overview of the effects of material- and process-related parameters on the various types of failures observed during and after heat treating of quenched and tempered steels. It describes phase transformations of steels during heating, cooling of steel with and without metallurgical transformation, and the formation of high-temperature transformation products on the surface of a carburized part. The article illustrates the use of carbon restoration on decarburized spring steels. Different geometric models for carbide formation are shown schematically. The article also describes the different microstructural features such as grain size, microcracks, microsegregation, and banding.

Quenchant agitation can be obtained by circulating quenchant in a quench tank through pumps and impellers. The selection of the agitation method depends on the tank design, type and volume of the quenchant, part design, and the severity of quench required. This article describes flow measurement methods, temperature control, materials handling, and filtration processes during the agitation process. The maintenance of quenching installations is also discussed.

This article describes various quenchants, namely, water and inorganic salt solutions, polymers (polyvinyl alcohol, polyalkylene glycol, polyethyl oxazoline, polyvinyl pyrrolidone and sodium polyacrylates), quench oils, and molten salts, which are used for heat treatment of ferrous alloys. It also provides information on the steps for controlling quenching performance for polymer quenchants and oils with an emphasis on measuring quenchant performance, safety measures, and oxidation.

Nanofluids offer a completely different behavior of wetting kinetics and heat-removal characteristics, which are exploited in industrial heat treatment for quenching. This article provides information on the important thermophysical properties of nanofluids, namely, thermal conductivity, viscosity, specific heat, density, and surface tension. It reviews wetting and boiling heat-transfer characteristics of nanofluids as quenchants and highlights the importance of using nanofluids as effective quench media for the hardening process during heat treatment. The article describes the effect of nanoparticle addition on the microstructure, mechanical properties of components, wetting kinetics, and kinematics.

Induction heating for hardening of steels has advantages from the standpoint of quenching because parts are individually processed in a controlled manner. This article provides information on the effect of agitation, temperature, hardening, residual stresses, and quenching media, on quenching. It also describes various quenching methods for steel induction heat treating, namely, spray quenching, immersion quenching, self or mass quenching, and forced air quenching. The article also reviews quench system design and quenchants and their maintenance.

This article provides a discussion on probes for laboratory tests and resultant curves of industrial quenching processes. It describes the scope of the tests, and the calculation of heat-transfer coefficient (HTC) based on the tests. The article highlights the differences between the laboratory tests and characterization of industrial quenching processes. It reviews the importance of initial heat-flux density and first critical heat-flux density. The theoretical principle behind and the purpose of the temperature gradient method are discussed. The article provides information on the design of the probe, heat-extraction dynamics, and influence of wetting kinematics. It also includes discussions on the simplified 1-D temperature-distribution model, calculation of the HTC, and the finite-volume method for the heat-conduction equation.

Inverse hardening a steel of adequate hardenability requires a workpiece of sufficiently large cross section, an appropriate cooling medium, and the right quenching conditions. This article explains the Temperature Gradient Quenching Analysis System (TGQAS), which can measure, record, and evaluate all quenching processes in common use, describing their heat extraction dynamics by corresponding thermodynamic functions. It discusses the metallurgical aspects of steels with an emphasis on two different processes, namely, heat extraction (a thermodynamic process) and microstructural transformation (a metallurgical process) that are initiated at the moment when the austenitized workpiece is immersed in the quenchant. The article describes the uses of polyalkylene glycol copolymer and the effect of hardness and fatigue resistance on AISI 4140 type steel.