Tempering of induction-hardened steel is a form of subcritical heat treatment, primarily carried out to increase ductility, toughness, and dimensional stability, to relieve residual stresses, and to obtain specific values of mechanical properties. This article describes tempering with emphasis on different time-temperature exposure requirements for furnace and induction tempering. It discusses two parametric methods for correlating equivalent time-temperature condition: Hollomon-Jaffe tempering correlation and Grange-Baughman tempering correlation. The article describes different methods of induction tempering, namely, single-shot, progressive or continuous, scanning, and static heating methods. The effects of induction heating variables and hardenability on tempering response are examined. The article also provides examples of how tempering affects the mechanical properties of induction-hardened steels.

Tempering of steel is a process in which hardened or normalized steel is heated to a temperature below the lower critical temperature and cooled at a suitable rate, primarily to increase ductility, toughness, and grain size of the matrix. This article provides an overview of the variables that affect the microstructure and mechanical properties of tempered steel, namely, the tempering temperature, tempering time, carbon content, alloy content, and residual elements. Tempering after hardening is performed to relieve quenching stresses and ensure dimensional stability of steel. The article discusses the embrittlement problems associated with tempering. Four types of equipment are used for tempering, namely, convection furnaces, salt bath furnaces, oil bath equipment and molten metal baths. Special procedures for tempering are briefly reviewed.

Steel, heated in contact with air at temperatures in the tempering range, takes on various temper colors due to the formation of a thin oxide film. This article provides detailed information on temper colors for plain carbon steel, especially on the effects of time and temperature.

Commercial aluminum alloys are classified based on how they are made and what they contain. This article describes the ANSI H35.1 designation system, which is widely used to classify wrought and cast aluminum alloys. The ANSI standard uses a four-digit numbering system to identify alloying elements, compositional modifications, purity levels, and product types. It also uses a multicharacter code to convey process-related details on heat treating, hardening, cooling, cold working, and other stabilization treatments. The article includes several large tables that provide extensive information on aluminum alloy and temper designations and how they correspond to critical mechanical properties as well as other designation systems.

This article presents a summary of aluminum temper designations, and applicable aluminum alloys and product forms for temper designations used in the United States (ANSI H35.1), Europe (EN 515), and internationally (ISO 2107).

In the case of steels, heat treatment plays a fundamental role because no other process step can manipulate the microstructure in order to fulfill such a wide variety of possible in-service conditions. This article addresses heat treatment with regard to hardening and subsequent tempering of steel components in order to optimize tribological properties. It focuses on the heat treatment of tempering and bearing steels and on volume changes that take place due to phase transformations. Plastic deformations that occur due to shrinking and phase transformation are also discussed. The article also describes the generation of thermal, transformation, and hardening residual stresses.

This article describes the systems for designating the aluminum and aluminum alloys that incorporate the product forms (wrought, casting or foundry ingots) and its respective temper for strain-hardened alloys, heat-treatable alloys and annealed alloys. All these systems are covered by American National Standards Institute (ANSI) standard H35.1. Furthermore, the article provides a short note on the designation of unregistered tempers.

The most widely accepted alloy and temper designation system for aluminum and its alloys is maintained by the Aluminum Association and recognized by the American National Standards Institute (ANSI) as the American National Standard Alloy and Temper Designation Systems for Aluminum (ANSI H35.1). This article provides a detailed discussion on the alloy and temper designation system for aluminum and its alloys. The Aluminum Association alloy designations are grouped as wrought and cast alloys. Lengthy tables provide information on alloying elements in wrought aluminum and aluminum alloys; nominal composition of aluminum alloy castings; typical mechanical properties of wrought and cast aluminum alloys in various temper conditions; and cross references to former and current cast aluminum alloy designations.

This article lists temper designations and their definitions for aluminum alloys along with their product forms used in the United States (ANSI H35.1), Europe (EN 515), and internationally (ISO 2107).