Search Results for liquid quenching

This article presents the fundamentals of induction hardening (IH). It focuses on liquid quenching technology, but some specifics and brief comments are provided regarding alternative quenching media as well. The article provides a discussion on the following quench modes that can be applied in IH using liquid media: conventional immersion quenching, open spray quenching, flood quenching, and submerged quench or submerged spray quench. It also focuses on four primary methods of IH: scan hardening, progressive hardening, single-shot hardening, and static hardening.

The gas quenching process is usually performed at elevated pressures, and is therefore, mostly referred to as high-pressure gas quenching (HPGQ). This article describes the physical principles of HPGQ; the two main types of equipment used, namely, single-chamber furnaces and cold chambers; and the three gases used, namely, nitrogen, helium, and argon. It also discusses two different groups of fixture materials used, namely, high-nickel-content alloys and carbon-fiber-reinforced carbon materials. The article exemplifies the process of dynamic gas quenching and how core hardness values can be predicted in industrial practices. It also discusses the improvements in distortion control with the application of gas-flow reversing and dynamic gas quenching.

Gas quenching is one of the standard quenching technologies used in fabricating metallic components. The gas quenching process is usually performed at elevated pressures and is therefore mostly referred to as high-pressure gas quenching (HPGQ). This article presents the physical principles of HPGQ and also presents the equipment for gas quenching. The article describes the three types of gas that are mainly used for HPGQ: nitrogen, helium, and argon. It provides the mathematical model for heat fluxes and temperatures during HPGQ. The article also presents typical industrial applications for HPGQ in addition to equipment process and safety.

This article describes the six fundamental factors that decide a tool's performance. These are mechanical design, grade of tool steel, machining procedure, heat treatment, grinding, and handling. A deficiency in any one of the factors can lead to a tool and die failure. The article presents a seven-step procedure to be followed when looking for the reason for a failure. A review of the results of the seven-point investigation may lead directly to the source of failure or narrow the field of investigation to permit the use of special tests.

This article illustrates the three techniques for producing glassy metals, namely, liquid phase quenching, atomic or molecular deposition, and external action technique. Devitrification of an amorphous alloy can proceed by several routes, including primary crystallization, eutectoid crystallization, and polymorphous crystallization. The article demonstrates a free-energy versus composition diagram that summarizes many of the devitrification routes. It provides a historical review of the corrosion behavior of fully amorphous and partially devitrified metallic glasses. The article describes the general corrosion behavior and localized corrosion behavior of transition metal-metal binary alloys, transition metal-metalloid alloys, and amorphous simple metal-transition metal-rare earth metal alloys. It concludes with a discussion on the environmentally induced fracture of glassy alloys, including hydrogen embrittlement and stress-corrosion cracking.

This article describes the uses of the liquid carburizing process carried out in low and high temperature cyanide-containing baths, and details the noncyanide liquid carburizing process which can be accomplished in a bath containing a special grade of carbon. It presents a simple formula for estimating total case depth, and illustrates the influence of carburizing temperature, duration of carburizing, quenching temperature, and quenching medium with the aid of typical hardness gradients. The article provides information on controlling of cyaniding time and temperature, bath composition, and case depth, and presents examples that relate dimensional change to several shapes that vary in complexity. It also provides information on the quenchant removal and salt removal processes, lists the applications of liquid carburizing in cyanide baths, and discusses the process and importance of cyanide waste disposal in detail.

Malleable iron possesses considerable ductility and toughness because of its combination of nodular graphite and a low-carbon metallic matrix. The desired formation of temper carbon in malleable irons has two basic requirements. First, graphite should not form during the solidification of the white cast iron, and second, graphite must also be readily formed during the annealing heat treatment. These two metallurgical requirements influence the useful compositions of malleable irons and the melting, solidification, and annealing procedures. There are two basic types of malleable iron: blackheart and whiteheart. This article considers only the blackheart type and describes the metallurgical factors of malleable iron. It discusses the mechanical properties of pearlitic and martensitic malleable irons. The article provides additional information on the properties and heat treatment of ferritic, pearlitic, and martensitic malleable irons. The article lists some of the typical applications of malleable iron castings.

Carburization is the process of intentionally increasing the carbon content of a steel surface so that a hardened case can be produced by martensitic transformation during quenching. Like carburizing, carbonitriding involves heating above the upper critical temperature to austenitize the steel. This article introduces the fundamentals, types, advantages and limitations, and the complications of various forms of carburizing, namely, pack carburizing, liquid carburizing or salt bath carburizing, gas carburizing, and low-pressure (vacuum) carburizing. The related process of carbonitriding is also briefly described in the article.

This article focuses on the heat removal stages involved in quenching, and on the experimental setup used for measuring temperature and detecting sound signals with the help of illustrations and curves. The quenching process generates acoustic signals, which are the consequences of the phase transformation of steel and of the boiling process at the interface during the cooling process. The sound-pressure signal is captured by the hydrophone through sound-emission measurements that occur during steel quenching in different quenching media. The analysis of the results offers an interesting approach to evaluation and, more importantly, to monitoring, controlling, and optimizing the entire quenching process.

This article discusses an experimental setup and a measuring setup for capturing acoustic emission during quenching. It presents the procedure for sound-emission measurement and an analysis of the acoustic spectrum obtained during quenching.

Malleable iron, like ductile iron, possesses considerable ductility and toughness because of its combination of nodular graphite and low-carbon metallic matrix. There are two basic types of malleable iron: blackheart and whiteheart. This article focuses on the blackheart malleable iron and discusses the chemical composition of malleable iron. A summary of mechanical properties and specifications of malleable iron castings is presented in a table. The article also reviews the mechanical properties of ferritic malleable iron and pearlitic and martensitic-pearlitic malleable irons.

Metallic glasses can be prepared by solidification of liquid alloys at cooling rates sufficient to suppress the nucleation and growth of competing crystalline phases. This article presents a historical survey of the study of metallic glasses and other amorphous metals and alloys. This includes a discussion of synthesis and processing methods, structure and morphology, and a description of the electronic, magnetic, thermodynamic, chemical, and mechanical properties of metallic glasses. In addition, the article describes the development of metallic glasses as materials for technical applications.