Tool steels are specialty steels, produced in relatively low volumes, optimized for applications requiring precise combinations of wear resistance, toughness, and hot hardness. This chapter describes the AISI classification system by which tool steels are defined. It discusses primary types, including high-speed and shock-resisting steels, and their associated subtype groups (W, L, S, O, A, D, H, M, and T series). It also discusses the types of carbides found in tool steels and their influence on mechanical properties. The chapter concludes with a discussion on heat treatment effects unique to tool steels, including two-phase effects, austenite stabilization, and the conditioning of retained austenite.

This chapter focuses on key requirements for obtaining third-generation advanced high-strength steels (AHSS). The discussion covers the microstructure design for AHSS, novel AHSS processing routes, the development of nanostructured AHSS, and the development of third-generation AHSS by the Integrated Computational Materials Engineering approach.

Dual-phase (DP) steels have the widest usage in automotive industry because of their excellent combination of strength and ductility. This chapter provides an overview of the composition, microstructure, processing, deformation mechanism, mechanical properties, formability, and special attributes of DP steels.

This chapter discusses the compositions, mechanical properties, phase structure, stabilization, corrosion resistance, and advantages of austenitic stainless steels. Austenitic alloys are classified and reviewed in three groups: (1) lean alloys, such as 201 and 301, which are generally used when high strength or high formability is the main objective; (2) chromium nickel alloys used for high temperature oxidation resistance; and (3) chromium, molybdenum, nickel, and nitrogen alloys used for applications where corrosion resistance is the main objective.

This chapter describes the various phases that form in tool steels, starting from the base of the Fe-C system to the effects of the major alloying elements. The emphasis is on the phases themselves: their chemical compositions, crystal structures, and properties. The chapter also provides general considerations of phases and phase diagrams and the determination of equilibrium phase diagrams. It describes the formation of martensite, characteristics of alloy carbides, and the design of tool steels.

Stainless steels derive their name from their exceptional corrosion resistance, which is attributed to their finely tuned compositions. This chapter discusses the alloying elements used in stainless steels and the some of the processing challenges they present. One of the biggest challenges is that stainless steels cannot be hardened by heat treatment. As a result, they are highly sensitive to processing-induced defects and the formation of detrimental phases. The chapter explains how alloy design, phase equilibria, microstructure, and thermomechanical processing can be concurrently optimized to produce high-quality austenitic, ferritic, and duplex stainless steels.

This chapter discusses the composition, alloying characteristics, mechanical properties, corrosion resistance, advantages, limitations, and applications of martensitic, semiaustenitic, and austenitic precipitation-hardenable stainless steels.

This chapter describes the iron-carbon phase diagram, its modification by alloying elements, and the effect of carbon on the chemistry and crystallography of austenite, ferrite, and cementite found in Fe-C alloys and steels. It also lays the groundwork for understanding important metallurgical concepts, including solubility, critical temperature, dislocation defects, slip, and diffusion, and how they affect the microstructure, properties, and behaviors of steel.

Alloy steels are alloys of iron with the addition of carbon and one or more of the following elements: manganese, chromium, nickel, molybdenum, niobium, titanium, tungsten, cobalt, copper, vanadium, silicon, aluminum, and boron. Alloy steels exhibit superior mechanical properties compared to plain carbonsteels as a result of alloying additions. This chapter describes the beneficial effects of these alloying elements in steels. It discusses the mechanical properties, nominal compositions, advantages, and engineering applications of various classes of alloy steels. They are low-alloy structural steels, SAE/AISI alloy steels, high-fracture-toughness steels, maraging steels, austenitic manganese steels, high-strength low-alloy steels, dual-phase steels, and transformation-induced plasticity steels.

This chapter addresses the issue of retained austenite in quenched carburized steels. It explains why retained austenite can be expected at the surface of case-hardened components, how to estimate the amount that will be present, and how to effectively stabilize or otherwise control it. It presents detailed images and data plots showing how retained austenite appears and how it influences hardness, tensile properties, residual stresses, fatigue and fracture behaviors, and wear resistance.

This chapter defines low-temperature and cryogenic steels and describes their alloy classifications and their ambient and low-temperature properties. These steels include ferritic carbon and low alloy steels, martensitic low alloy steels, martensitic high alloy steels, and austenitic high alloy steels.

The decomposition of austenite, during controlled cooling or quenching, produces a wide variety of microstructures in response to such factors as steel composition, temperature of transformation, and cooling rate. This chapter provides a detailed discussion on the isothermal transformation and continuous cooling transformation diagrams that characterize the conditions that produce the various microstructures. It discusses the mechanism and process variables of quenching of steel, explaining the factors involved in the mechanism of quenching. In addition, the chapter provides information on the causes and characteristics of residual stresses, distortion, and quench cracking of steel.

This chapter discusses the classification, composition, properties, and applications of five types of stainless steels: austenitic, ferritic, duplex, martensitic, and precipitation-hardening steels. It discusses the process involved in argon oxygen decarburization that is used to refine stainless steel. The chapter also provides information on the classification and composition of stainless steel castings. It concludes with a brief description of the Schaeffler constitution diagram which is useful in predicting the type of stainless steel as a function of its alloy content.

This chapter is a detailed account of the applications of stainless steel in automotive and transport systems. The discussion covers exhaust systems, structural components, automotive components, trucks, and rail transport.