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.

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.

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.

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.

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.

This article discusses the characteristics, composition limits, and classification of wrought tool steels, namely high-speed steels, hot-work steels, cold-work steels, shock-resisting steels, low-alloy special-purpose steels, mold steels, water-hardening steels, powder metallurgy tool steels, and precision-cast tool steels. It describes the effects of surface treatments on the basic properties of tool steels, including hardness, resistance to wear, deformation, and toughness. The article provides information on fabrication characteristics of tool steels, including machinability, grindability, weldability, and hardenability, and presents a short note on machining allowances.

This article describes procedures for producing powder metallurgy high-speed tool steel powder by inert-gas atomization, followed by compaction by hot isostatic pressing. These include the anti-segregation process (ASP) and the crucible particle metallurgy (CPM) process. The article reviews the properties of ASP and CPM and summarizes the procedures to heat treat ASP high-speed tool steels. It discusses the processing steps, advantages, and applications of the FULDENS process that uses water-atomized powders compacted by vacuum sintering. The article also provides information on the applications of tool steels.

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.

The powder metallurgy (P/M) process has been used primarily for the production of advanced high-speed tool steels. However, the P/M process is also being applied to the manufacture of improved cold-work and hot-work tool steels. The basic heat treatments for P/M high-speed tool steels include preheating, austenitizing, quenching, and tempering. This article describes manufacturing properties, cutting tool properties, and applications of P/M high-speed tool steels. It discusses the development of P/M high-speed alloy steels that cannot be made by conventional methods because of their high carbon, nitrogen, or alloy contents. For high-speed tool steels, a number of important end-user properties have been improved by powder processing; machinability, grindability, dimensional control during heat treatment, and cutting performance under difficult conditions where high edge toughness is essential. Several of these advantages also apply to P/M cold- and hot-work tool steels, which, compared to conventional tool steels, offer better toughness and ductility for cold-work tooling, better thermal fatigue life, and greater toughness for hot-work tooling.

This article provides a discussion on the machining guidelines that serve to improve the machinability of powder metallurgy materials. It provides a description of various cutting tool grades and tool-edge design and describes the machining conditions for common operations, namely, turning, drilling, tapping, grinding, and finishing. The article introduces a few overlooked details that can heavily influence the performance and success of the machining process. These include dwell, margin design on round tools, and proper edge hone.

This article reviews the production variables that influence the selection of various stamping die materials: ferrous, nonferrous, and plastic die materials. It provides a discussion on the specific types of die materials for tool steels, cast irons, plastics, aluminum, bronze, zinc-aluminum, and steel-bonded carbides. The article describes factors to be considered during the selection of materials for press-forming dies.

Wrought powder metallurgy (P/M) high-speed tool steels exhibit better machinability, dimensional control and safety in heat treatment, grindability, and edge toughness during cutting. This article discusses the two stages of machining of P/M tool steels: rough machining, in annealed condition, and finish machining, in hardened-and-tempered condition. It tabulates the composition of commercial crucible particle metallurgy and anti-segregation process tool steels and their typical machining conditions.

This article describes the capabilities, limitations, advantages, and disadvantages of the powder metallurgy (PM) gear manufacturing process. It discusses the types of gears that can be produced by PM and presents the design guidelines for PM gears. The article provides information on gear tolerances and performance of PM gears. It also explains various procedures to inspect and test the mechanical properties, dimensional specifications, and surface durability (hardness).

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 reviews various segments of the powder metallurgy (PM) process from powder production and powder processing through the characterization of the materials and their properties. It covers the processing methods for consolidating metal powders including options for processing to full density. The article outlines the freeform fabrication process, also known as additive manufacturing and describes finishing operations of PM parts. It concludes with information on the applications of PM parts.

High-temperature sintering of ferrous components continues to be important in the powder metallurgy (PM) industry. Improvements in both production rates and properties are possible as sintering temperatures increase above 1120 deg C. This article provides an overview of the different various stages of the sintering process and the physical, chemical, and metallurgical phenomena occur within the mass of metal powder particles. It discusses the four advantages of high-temperature sintering of various ferrous PM materials: improved mechanical properties, improved physical properties, development of liquid phase, and ability to sinter active elements in alloy steels. The article also provides information on three sources of process control requirements, namely, the powder blend, green density, and sintering conditions.

Powder metallurgy is a near-net shape process capable of producing complex parts with little or no need for secondary operations such as machining, joining, or assembly. However, the inability to produce certain geometrical figures such as transverse holes, undercuts, and threads frequently necessitates some machining, particularly drilling. This article provides a discussion on the measures that can optimize the machining of P/M materials. It reviews the factors influencing machinability of P/M components, including workpiece and tool material properties, cutting conditions, machine and cutting tool parameters as well as some P/M material and production process parameters. These parameters discussed include the particle size, part geometry, porosity, compaction and sintering methods. In addition, the article presents guidelines for the various machining processes, namely, turning and boring, milling, drilling, grinding, reaming, burnishing, tapping, and honing and lapping.

This article provides an overview of the compaction of metal powder in a rigid die and reviews the compaction characteristics of stainless steel powders, including green density, compressibility, green strength, apparent density, flow rate, and sintered density. It describes the influence of compaction characteristics of stainless steel powders in tool materials selection, lubrication, annealing, double pressing/double sintering, and warm compaction.