This article describes some of the underlying factors of tool steel and bearing steel fractures and appearances. It also briefly introduces the general types of cold work and hot work tool steels and their typical performance requirements. This includes the importance of microstructural conditions achieved with powder metallurgy (PM) tool steels and the need for steel “cleanliness,” especially in preventing contact fatigue in bearings or bending fatigue in gears.

This article discusses failure mechanisms in tool and die materials that are very important to nearly all manufacturing processes. It is primarily devoted to failures of tool steels used in cold working and hot working applications. The processes involved in the analysis of tool and die failures are also covered. In addition, the article focuses on a number of factors that are responsible for tool and die failures, including mechanical design, grade selection, steel quality, machining processes, heat treatment operation, and tool and die setup.

This article provides a brief overview of additive manufacturing (AM) of tool steels via various AM technologies such as laser powder bed fusion, electron powder bed fusion, blown powder directed energy deposition, and binder jet AM. The discussion includes process overview and covers the mechanism, advantages, and applications of each of these techniques.

Tool steels are carbon, alloy, and high-speed steels that can be hardened and tempered to high hardness and strength values. This article discusses the classifications of commonly used tool steels: water-hardening tool steels, shock-resisting tool steels, cold-work tool steels, and hot-work tool steels. It describes four basic mechanisms of tool steel wear: abrasion, adhesion, corrosion, and contact fatigue wear. The article describes the factors to be considered in the selection of lubrication systems for tool steel applications. It also discusses the surface treatments for tool steels: carburizing, nitriding, ion or plasma nitriding, oxidation, boriding, plating, chemical vapor deposition, and physical vapor deposition. The article describes the properties of high-speed tool steels. It summarizes the important attributes required of dies and the properties of the various materials that make them suitable for particular applications. The article concludes by providing information on abrasive wear and grindability of powder metallurgy steels.

This article discusses the methods and procedures used to extract, purify, and synthesize tungsten carbide powder, metal, and other refractory carbide/nitride powders used in hard metal production. Selection of powders, additives, equipment, and processes for making ready-to-press hard metal powders is also discussed. The article also provides information on the emerging technologies for tungsten carbide synthesis and binders in hard metal production, such as cobalt, iron, and nickel.

Powder metallurgy (PM) high-alloy tool steels (HATS) have unique properties that assist them in solving various problems related to machining of metal components. This article describes the cost-intensive PM processing routes of HATS, as well as their major properties, including elastic properties, density, mechanical properties, grindability, fatigue and wear resistance, and thermophysical properties.

High-potential high-alloy tool steels (HATS) containing martensitic microstructure with undissolved hard phases are achieved by a number of complex heat treating cycles, predominantly tempering. This article focuses on three tempering treatments, namely, salt bath heat treatment, austenitizing, and vacuum heat treatment. It explains the result of these tempering processes with HSS M2 grade of HATS.

This article describes the effects of undissolved carbides formed by segregation of alloying elements on the hardness of the powder-metallurgical (PM) high-alloy tool steels (HATS). It explains the calculation of exact stoichiometric carbon content that depends on the required martensite hardness, amount of carbon forming alloying elements, types of undissolved carbides during austenitizing, and the densities of the carbides. Microhardness values for carbides in HATS are also listed.

This article is a comprehensive collection of tables that list the nominal chemical composition of common powder metallurgy (PM) high-alloy tool steels, namely, PM high-speed, cold working, and corrosion-resistant tool steels.

The microstructure in the longitudinal direction of conventional high-alloy tool steels (HATS) depends very much on the degree of hot working. Comparing different processes, the highest processing temperature proves to be decisive for coarseness of the microstructure. This article provides a discussion on the microstructure of conventional HATS and hot isostatically pressed high-speed steel. The effects of the processing in cold worked HATS are illustrated.

Tool steels are an important class of steels due to their distinct applications and their specific heat treating issues. This article provides an overview of the classification and production of tool steels, and discusses the procedures and process control requirements for heat treating principal types of tool steels. It reviews the various heat treating processes, namely, normalizing, annealing, stress relieving, austenitizing, quenching, and tempering, and surface treatments and cold treating. The article also provides information on the applicability of these processes to various types of tool steels.

The design of a tool-steel part directly affects the susceptibility to shape distortion on heating and cooling. This article provides information on the selection of chemical composition and the effect of composition on size distortion. It explains the various factors considered to control distortion in tools steels, namely, design, initial condition, machining procedure, and heat treatment. Distortion can occur both during and after heat treatment. The article discusses the chief ways to precisely control the extent of distortion by heat treating and auxiliary mechanical methods. Stabilizing treatments, namely, stabilizing by tempering and stabilizing by cold treatment are used to minimize dimensional changes that occur following heat treatment.

Quench cracking is a brittle fracture phenomenon, and its occurrence depends not only on the stress changes but also on the mechanical characteristics of metals. Simulation of quenching processes has become possible in the analysis of quench cracking. This article commences with a discussion on the studies conducted to determine the origin of quench cracks, and then describes various test procedures for determining the susceptibility of quench cracking. It provides a description of the brittle fracture in terms of fracture mechanics and fracture toughness of quenched metals, and discusses the effects of impurities, hydrogen, and surface roughness on cracking. The article exemplifies simulation works applied to several successful cracking tests on cylindrical and complex-shaped steel parts.

Distortion, encompassing all irreversible dimensional changes, is of two main types: size distortion and shape distortion. This article provides an overview of the nature and causes of distortion and discusses the process and material aspects of distortion specific to steels and tool steels. It also discusses the prediction of distortion and residual stresses by heat treatment simulation for optimizing production processes. The advantages and limitations of heat treatment simulation are also described.

This article provides a detailed discussion on the heating equipment used for austenitizing, quenching, and tempering tool steels. These include salt bath furnaces, controlled atmosphere furnaces, fluidized-bed furnaces, and vacuum furnaces. The article discusses the types of nitriding and nitrocarburizing processes and the equipment required for heat treating tool steels to improve hardness, wear resistance, and thermal fatigue. The various nitriding and nitrocarburizing processes covered are salt bath nitrocarburizing, gas nitriding and nitrocarburizing, and plasma nitriding and nitrocarburizing.

This article focuses on heat treating of the most important H-series and low-alloy hot-work tool steels, namely, normalizing, annealing, stress relieving, preheating, austenitizing, quenching, tempering, and surface hardening. It describes the heat-treating procedure for hot-work tools using examples. The article provides information on the North American Die-Casting Association's requirements for steel grades and heat treatment of dies made of hot-work tool steels. It also describes the chemical compositions and mechanical and metallurgical properties of hot-work tool steels.

Air hardening steel is a type of steel that has deep hardenability and can be hardened in large sections by air cooling. This article discusses the principles of heat treatment of air-hardening steel, and describes the recommended heat treating practices for air-hardening high-strength structural steels, namely, H11 Mod, H13 steel, 300M steel, D-6A and D-6AC, and AF1410 steel. It also provides information on recommended heat treating practices for air-hardening martensitic stainless steels.

This article provides a detailed discussion on various recommended heat treating practices, including normalizing, annealing, austenitizing, quenching, tempering, stress relieving, preheating, and martempering, for various low- and un-alloyed cold-work hardening tool steels. The steels discussed include water-hardening tool steels, shock-resisting tool steels, oil hardening cold-work tool steels, low-alloy special-purpose tool steels, and carbon-tungsten special-purpose tool steels.

This article focuses on various heat-treating practices, namely, normalizing, annealing, stress relieving, preheating, austenitizing, quenching, tempering, and nitriding for cold-work tool steels. The cold-work tool steels include medium-alloy air-hardening tool steels, high-carbon high-chromium tool steels, and high-vanadium-powder metallurgy tool steels. The article also describes the properties, types, nominal compositions and designations of these cold-work tool steels.