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.

High-speed tool steels have in common the ability to maintain high hardness at elevated temperatures. High speed steels are primarily used for cutting tools that generate heat during high-speed machining. They are designated as group M or group T steels in the AISI classification system, depending on whether the major alloying approach is based on molybdenum or tungsten. This chapter describes the effects of each of the alloying elements and carbon content on the processing, microstructures, and properties of high-speed steels. It discusses the processes involved in the solidification, hot work, annealing, austenitizing for hardening, and tempering of high-speed steels. It also discusses the processes involved in controlling grain size during austenitizing and reviews the characteristics of cooling transformations and other property changes in tempered high-speed steels. Information on multipoint cutting tools is provided. The chapter discusses the applications of high-speed tool steel and factors in selecting high-speed tool steels.

This chapter provides a detailed account of the development of tool steel technology. It begins with a record of steelmaking in ancient and medieval times. The crucible melting process involved in making steel is then discussed. This is followed by a description of the increasing use of alloys for tool steels. The chapter provides information on the research investigations into the metallurgy of high-speed tool steels at MIT, Union Carbide, and Carbon Laboratories. The major research effort involved in substituting molybdenum for tungsten in high-speed tool steels is discussed. The chapter also describes the role of the Cleveland Twist Drill Company as the first adopter of molybdenum high-speed steel. It ends with a discussion on the advanced work on high-speed steels by Swedish researchers.

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.

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.

This chapter focuses on the metallurgical factors governing the machinability of stainless steels. It begins by describing the chemistry, cleanliness, structure, processing history, and the cross-section size of the stock of the different grades of stainless steel. This is followed by a general description of the machining behavior of the stainless steel families, namely ferritic, martensitic, austenitic, precipitation hardening, duplex, and super stainless steels. The beneficial effect of controlled inclusions is then discussed. The chapter ends with a section providing information on high-speed tool steel and carbide tooling, along with tool coatings and coolants applicable to stainless steel.

This chapter focuses on the failure aspects of tool steels. The discussion covers the classification, chemical composition, main characteristics, and several failures of tool steels and their relation to heat treatment. The tool steels covered are hot work, cold work, plastic mold, and high-speed tool steels.

Surface modification technologies improve the performance of tool steels. This chapter discusses the processes involved in oxide coatings, nitriding, ion implantation, chemical and physical vapor deposition processing, salt bath coating, laser and electron beam surface modification, and boride coatings that improve the performance of hot-work and high-speed tool steels.

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.