Resumen
The aim of this chapter is to outline the basic concepts of physical metallurgy relating to the heat
treatment of steel.
Heat treatment is defined as subjecting a material to controlled heating and cooling cycles. The
number of cycles, temperature, and duration of the treatment depend on the material being
treated and the purpose for which it is treated. Heat treatments alter the microstructure and
mechanical properties of steel. Properties can be modified during the steel forming process to
facilitate its shaping, and modified again as needed with heat treatments to comply with the final
design.
The capacity of steel of modifying its microstructure and properties as a result of heat treatment
makes it one of the most versatile materials in engineering design. Steel components are
subjected to specific heat treatments to achieve the properties required for a given application.
Heat treatment is typically employed to optimize the properties of a specific steel grade, such as
strength and hardness, while balancing these with toughness and corrosion resistance. It is
noteworthy that depending on the specific heat treatment conditions applied, the mechanical
properties of a specific steel composition can vary across a wide range; for example, yield
strength can be increased from 200 to 2,500 MPa (30 to 360 Ksi) through quench–hardening
[1].
Quenching involves rapid and controlled cooling from a high temperature (above the critical
temperature of steel). The cooling rate (in °C/s or °F/s) and chemical composition of the material
subjected to quenching are primarily responsible for the types and extents of transformations
that occur in the microstructure of the material; thus, the cooling rate is key to the properties
obtained. The quench-hardening of steel produces the hardest and most brittle structures.
Tempering is a subsequent treatment carried out at moderate temperature to reduce the
strength and hardness obtained after quenching and increase toughness; i.e., it reduces the
brittleness of the material obtained.
The phases and microstructures of steel are considered in this chapter together with the
transformations observed and critical temperatures during heat treatment. Additionally, the
different types of steels, heat treatments, and their purposes are discussed.
treatment of steel.
Heat treatment is defined as subjecting a material to controlled heating and cooling cycles. The
number of cycles, temperature, and duration of the treatment depend on the material being
treated and the purpose for which it is treated. Heat treatments alter the microstructure and
mechanical properties of steel. Properties can be modified during the steel forming process to
facilitate its shaping, and modified again as needed with heat treatments to comply with the final
design.
The capacity of steel of modifying its microstructure and properties as a result of heat treatment
makes it one of the most versatile materials in engineering design. Steel components are
subjected to specific heat treatments to achieve the properties required for a given application.
Heat treatment is typically employed to optimize the properties of a specific steel grade, such as
strength and hardness, while balancing these with toughness and corrosion resistance. It is
noteworthy that depending on the specific heat treatment conditions applied, the mechanical
properties of a specific steel composition can vary across a wide range; for example, yield
strength can be increased from 200 to 2,500 MPa (30 to 360 Ksi) through quench–hardening
[1].
Quenching involves rapid and controlled cooling from a high temperature (above the critical
temperature of steel). The cooling rate (in °C/s or °F/s) and chemical composition of the material
subjected to quenching are primarily responsible for the types and extents of transformations
that occur in the microstructure of the material; thus, the cooling rate is key to the properties
obtained. The quench-hardening of steel produces the hardest and most brittle structures.
Tempering is a subsequent treatment carried out at moderate temperature to reduce the
strength and hardness obtained after quenching and increase toughness; i.e., it reduces the
brittleness of the material obtained.
The phases and microstructures of steel are considered in this chapter together with the
transformations observed and critical temperatures during heat treatment. Additionally, the
different types of steels, heat treatments, and their purposes are discussed.
| Idioma original | English |
|---|---|
| Título de la publicación alojada | Handbook of Quenchants and Quenching Technology |
| Editorial | ASM International |
| Capítulo | 1 |
| Número de páginas | 66 |
| Estado | Accepted/In press - 2019 |