The water-hardening steels are either essentially plain carbon steels or very low-alloy carbon steels. As a result, the water-hardening tool steels are the least expensive of tool steels and require strict control of processing and heat treatment to achieve good properties and performance. This chapter provides an overview of general processing and performance considerations of water-hardening tool steels. It describes the microstructural characteristics and hardenability of water-hardening tool steels. The chapter discusses the processes involved in the hardening and tempering of water-hardening tool steels.

The low-alloy special-purpose tool steels, designated as group L steels in the AISI classification system, are similar to the water-hardening tool steels but have somewhat greater alloy content. This chapter discusses the metallurgy and performance of low-alloy special-purpose tool steels, including those with high carbon content, those with medium carbon content, and those containing nickel.

There is a fairly wide variety of different tool steels for different applications. The American Iron and Steel Institute (AISI) classification of tool steels includes seven major categories: water-hardening tool steels, shock-resisting tool steels, cold work tool steels, hot work tool steels, low-alloy special-purpose tool steels, mold tool steels, high-speed tool steels, and powder metallurgy tool steels. This chapter provides discusses the manufacturing process, composition, properties, types, and applications of these tool steels and other cutting tool materials, such as cemented carbides. It also describes the methods of applying coatings to cutting tools to improve tool life.

The several specific grades or compositions of tool steels have evolved over time and have been organized into useful groupings. This chapter presents the AISI classification system for tool steels, which categorizes tool steels by their alloying, applications, or heat treatment, and briefly describes the characteristics of each major group. It discusses selection criteria for tool steels, along with examples.

Tool steels represent a small, but very important, segment of the total production of steel. Their principal use is for tools and dies that are used in the manufacture of commodities. For the most part, the processes used for heat treating carbon and alloy steels are also used for heat treating tool steels, that is, annealing, austenitizing, tempering, and so forth. This chapter focuses on these heat treating processes of tool steels. Classification and approximate compositions and heating treating practices of some principal types of tool steels are provided. The steel types discussed include water-hardening; shock-resisting; oil-hardening cold-work; air-hardening, medium-alloy cold-work; high-carbon, high-chromium cold-work; low-alloy, special-purpose; mold; hot-work; and high-speed tool steels.

The possible classification for tool steels is their division into four groups according to their final application: hot-worked, cold-worked, plastic mold, and high-speed tool steels. This chapter mainly follows such division by application, but the grade nomenclatures used here are primarily from AISI. It presents the classification of tool steels and discusses the principles and processes of tool steel heat treating, namely normalizing, annealing, hardening, and tempering. Various factors associated with distortion in several tool steels are also covered. The chapter discusses the composition, classification, and properties of unalloyed and low-alloy cold-worked tool steels; medium and high-alloy cold-worked tool steels; and 18% nickel maraging steels.

Tools steels are defined by their wear resistance, hardness, and durability which, in large part, is achieve by the presence of carbide-forming alloys such as chromium, molybdenum, tungsten, and vanadium. This chapter describes the alloying principles employed in various tool steels, including high-speed, water-hardening, shock-resistant, and hot and cold work tool steels. It discusses the influence of alloy design on the evolution of microstructure and properties during solidification, heat treating, and hardening operations. It also describes critical phase transformations and the effects of partitioning, precipitation, segregation, and retained austenite.

This article provides an overview of tool steels, discussing their composition, properties, and behaviors. It covers all types and classes of wrought and powder metal tool steels, including high-speed steels, hot and cold-work steels, shock-resisting steels, and mold steels. It explains how the properties of these steels are determined by alloying elements, such as tungsten, molybdenum, vanadium, manganese, and chromium, and the presence of alloy carbides. It describes the types of carbides that form and how they contribute to wear resistance, toughness, high-temperature strength, and other properties.

This chapter presents an overview of some of the major causes of tool and die failures. The chapter describes fracture and fracture toughness of tool steels, and the influence of factors such as steel quality and primary processing, mechanical design, heat treatment, grinding and finishing, and distortion and dimensional change.

This chapter discusses the processes involved in heat treating of stainless steels, providing information on the classification, chemical compositions, and corrosion resistance of stainless steels. Five groups of stainless steels are discussed: austenitic, ferritic, martensitic, precipitation-hardening, and duplex grades. The chapter also describes the heat treatment conditions that should be followed for processing of stainless steels.

Tool steels are a special class of alloys designed for tool and die applications. High-speed steels are a subset of tool steels designed to operate at high speeds. This chapter describes the composition, properties, heat treatment, and use of wrought and alloyed tool steels, high-speed steels, and their counterparts made by powder metallurgy. It includes information on the chemical composition and application range of many commercial tool steels and explains how to apply coatings that reduce friction, thermal conductivity, and wear.

Mold steels are used for plastic molding and certain die-casting applications and are designated as group P steels in the AISI classification system. The fabrication and performance requirements that differentiate them from other types of tool steels are described in this chapter. It provides information on hubbing and machined cavity grades of mold steels and describes the performance of the corrosion-resistant mold steels. The chapter discusses the processes involved in forging, annealing, stress relieving, carburizing, hardening, and tempering of mold steels. It presents the selection criteria and applications of mold steels.