Search Results for quench-process design

This article provides an overview of the effects of various material- and process-related parameters on residual stress, distortion control, cracking, and microstructure/property relationships as they relate to various types of failure. It discusses phase transformations that occur during heat treating and describes the metallurgical sources of stress and distortion during heating and cooling. The article summarizes the effect of materials and the quench-process design on distortion and cracking and details the effect of cooling characteristics on residual stress and distortion. It also provides information on the methods of minimizing distortion and tempering. The article concludes with a discussion on the effect of heat treatment processes on microstructure/property-related failures.

This article presents an overview of the techniques used in the design for heat treatment and discusses the primary criteria for design: minimization of distortion and undesirable residual stresses. It provides theoretical and empirical guidelines to understand the sources of common heat treat defects. A simple example is presented to demonstrate how thermal and phase-transformation-induced strains cause dimensional changes and residual stresses. The article concludes with a discussion on the heat treatment process modeling technology.

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 detailed discussion on the heating equipment used for austenitizing, quenching, and tempering tool steels. These include salt bath furnaces, controlled atmosphere furnaces, fluidized-bed furnaces, and vacuum furnaces. The article discusses the types of nitriding and nitrocarburizing processes and the equipment required for heat treating tool steels to improve hardness, wear resistance, and thermal fatigue. The various nitriding and nitrocarburizing processes covered are salt bath nitrocarburizing, gas nitriding and nitrocarburizing, and plasma nitriding and nitrocarburizing.

The basic elements of control design are safety, process control, process verification, machine control, productivity, repeatability, and ease of setup. Effective systems of quality control/quality assurance are essential for heat treating practices. This article provides information on process control modes, as well as on process signatures of some items that require control, monitoring, verifying, and logging methods. It provides information on programmable logic controllers that have become efficient in machine control and monitoring. The article describes possible noise issues, National Electric Code clearance requirements, monitoring requirements, and machine accuracy that need to be considered when designing induction equipment.

Intensive quenching (IQ) is an alternative method of hardening steel parts. Two types of IQ methods are used in heat treating practice: IQ-2 and IQ-3. IQ-2 is implemented in IQ water tanks, which are usually used for batch quenching of steel parts. IQ-3 is conducted in single-part processing using high-velocity water flow IQ units. This article presents a detailed description of IQ technology, related equipment, and IQ applications. A review of intensive quench system design and processing is provided, including numerical design criteria, steel selection, quenchants, properties (especially optimal residual stress profiles). Several specific applications of intensive quenching are also provided.

Scanners are the most versatile and flexible of the equipment available to the heat treating industry for induction hardening. This article provides a general overview of scanners, and describes various critical factors, including scan speeds, rotational speeds, and center total indicator runout of vertical scanners. It presents information on the frequency selection parameters for scanning applications. The article also discusses the critical parameters and production rates in specifying and developing a tooth-by-tooth hardening process.

Press quenching is a specialized quenching technique that can be utilized during heat treatment to minimize distortion of complex geometrical components by using specialized tooling for generating concentrated forces that constrain the movement of the component in a carefully controlled manner. This article provides a detailed account of the fundamental components of quenching machines, including the upright machine section, control panel, lower die table, tooling, and the base. In addition, it summarizes the critical factors affecting component distortion during press-quenching.

Computational fluid dynamics (CFD) provides an efficient, alternate, virtual approach for simulating and analyzing quenching processes with an impact on component design, manufacturing process, and quality. This article provides domain insights for quenching researchers and CFD practitioners for the modeling of the industrial quenching process and for supporting the diverse multifunctional needs in an industry, ranging from primary metallurgical companies (steel, aluminum, and other alloys), original equipment manufacturers, engineering companies, captive and commercial heat treating facilities, quench system manufacturers, and quench fluid suppliers. It describes the governing differential equations for the fluid flow and heat-transfer phenomena during quenching. The article also discusses different modeling categories to determine a CFD methodology for quenching.

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.

Quenching is one of the most important heat treating processes, because it is so closely related to dimensional control requirements and control of residual stresses. This article provides an overview of the fundamental material- and process-related parameters of quenching on residual stress, distortion control, and cracking. This overview is followed by various selected case histories of failures attributed to the quenching process.

Molten salt, including nitrite/nitrate salts, is the quenching medium most commonly used in austempering and marquenching of ferrous materials. This article describes the use of molten salts in the quenching of ferrous materials. It provides information on the processing and operation of salt quenching including considerations of time, temperature, environment, and safety, as well as critical characteristics such as the composition of the quenchant, agitation, and water additions.

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.

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.

Mathematical models have been used for over five decades in industrial heat-treating operations. Most of these modeling efforts have emanated from academia or research institutes, with the primary approach of mathematically capturing heat-treating processes and validating quality predictions. In this article, a contrarian but more realistic scenario is considered, where two industrial problem descriptions become the starting point. The technical complexity of the industry problem has been elaborated for a deeper understanding of the issue along with elaboration of the approach and potential methods for determining a solution. Then, quantitative analyses of practical industrial problems are demonstrated. Finally, the potential shift in these approaches with the advent of Industry 4.0 is outlined.

The fluidized bed provides a means for exchanging heat between a metal part, the solid particles, and the fluidizing gas and which is viable for quenching. This article briefly considers the design aspects of the gas distributor, plenum, container, immersed cooling tubes and surface air spray cooling system in the quenching fluidized bed. It describes the fundamental factors affecting quenching power of the fluidized beds, namely, particle size, particle material, fluidizing gas composition, fluidizing gas flow rate, bed temperature and pressure, and the arrangement of quenched parts with respect to one another and to the bed. The article discusses the advantages, disadvantages, various applications and processes, including conventional batch quenching, two-step batch quenching, and continuous quenching of fluidized bed quenching, in detail.

This article provides an overview of steel gear heat treating processes and brings out the nuances of the various important heat treating considerations for steel gear applications. The heat treatment processes covered are annealing, carburizing, hardening, low-pressure carburizing, induction hardening, through hardening, and nitriding. In view of the emerging use of mathematical modeling and optimization, a brief overview of its application for process and design optimization is also provided.

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 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.

This article describes some of the underlying factors of tool steel and bearing steel fractures and appearances. It also briefly introduces the general types of cold work and hot work tool steels and their typical performance requirements. This includes the importance of microstructural conditions achieved with powder metallurgy (PM) tool steels and the need for steel “cleanliness,” especially in preventing contact fatigue in bearings or bending fatigue in gears.