Quenching is one of the most important heat treating processes, because it is so closely related to dimensional control requirements and control of residual stresses. This article provides an overview of the fundamental material- and process-related parameters of quenching on residual stress, distortion control, and cracking. This overview is followed by various selected case histories of failures attributed to the quenching process.

Of the various thermal processing methods for steel, heat treating has the greatest overall impact on control of residual stress and on dimensional control. This article provides an overview of the effects of material- and process-related parameters on the various types of failures observed during and after heat treating of quenched and tempered steels. It describes phase transformations of steels during heating, cooling of steel with and without metallurgical transformation, and the formation of high-temperature transformation products on the surface of a carburized part. The article illustrates the use of carbon restoration on decarburized spring steels. Different geometric models for carbide formation are shown schematically. The article also describes the different microstructural features such as grain size, microcracks, microsegregation, and banding.

Shaping and slotting are used to remove metal from surfaces through the use of a single-point tool supported by a ram that reciprocates the tool in a linear motion against the workpiece. This article discusses the process capabilities of shaping and slotting with respect to the size and configuration of the workpiece. Shaping and slotting machines develop cutting action from a straight-line reciprocating motion between the tool and the workpiece. The article describes the types of shapers such as horizontal shaper and vertical shaper. It briefly discusses the applications of high-speed steel tools and carbide tools for shaping. The article also illustrates the dimensional control of workpieces during shaping. It concludes with a discussion on gear shaping.

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.

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.

Fusion welding induces residual stresses and distortion, which may result in loss of dimensional control, costly rework, and production delays. In thermal analysis, conductive heat transfer is considered through the use of thermal transport, heat-input, and material models that provide values for the applied welding heat input. This article describes how the solid-phase transformations that occur during the thermal cycle produced by welding lead to irreversible plastic deformation known as transformation plasticity. Residual stress and welding distortion are also discussed.

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.

This article reviews the emerging manufacturing technology that is alternatively called additive manufacturing (AM), direct digital manufacturing, free-form fabrication, three-dimensional (3-D) printing, and so on. It provides a broad contextual overview of metallic AM. The article focuses on the mechanical properties of AM-processed Ti-6Al-4V, IN-625, and IN-718. The development of closed-loop, real-time, sensing, and control systems is essential to the qualification and advancement of AM. This involves the development of coupled process-microstructural models, sensor technology, and control methods and algorithms. AM has the potential to revolutionize the global parts manufacturing and logistics landscape. It enables distributed manufacturing and the productions of parts on demand while offering the potential to reduce cost, energy consumption, and carbon footprint. The article explores the materials science, processes, and business considerations associated with achieving these performance gains. It concludes that a paradigm shift is required to fully exploit AM potential.

Forgings are classified in various ways, beginning with the general classifications open die and closed die. They are also classified according to how they are made; such as hammer upset forgings, ring-rolled forgings, and multiple-ram press forgings; and in terms of the close-to-finish factor or amount of stock that must be removed to satisfy the dimensional and detail requirements of the finished part. In addition to types and classifications, the article discusses critical design factors and ways to ensure that the resulting forgings measure up to metallurgical, mechanical property, and dimensional accuracy requirements. The responsibility for design verification is vested in material control, which depends on the proper application of drawings, specifications, manufacturing process controls, and quality assurance programs. The article addresses each of these areas as well as related topics; including stress-induced fatigue failure, tolerances, machining allowances; and the fundamentals of hammer and press forgings, hot upset forgings, and hot extrusion forgings.

Braided structures are unique in their high level of conformability, torsional stability, and damage resistance. This article describes the classifications of braiding such as two-dimensional braiding and three-dimensional braiding. It presents the governing equations for computer-controlled braiding in a table. The article lists the applications of braided fabrics and composites. It discusses the formation, structure, and properties of two-dimensional braid composites and three-dimensional braid composites: the damage tolerance and the impact damage limitation.

Consolidation and shaping of grade powders is carried out using several methods, depending on the size, complexity, shape, and quantity of parts required. This article details the powder consolidation methods of carbide powders: uniaxial pressing, cold isostatic pressing, extrusion, green machining, and injection molding.

Sheet forming comprises deformation processes in which a metal blank is shaped by tools or dies, primarily under the action of tensile stresses. This article discusses the classification of sheet-forming processes for obtaining desired dimensional features. It describes different process-related developments, namely, superplastic forming of aluminum, forming of tailor-welded blanks, rubber-pad forming, and high-velocity metal forming. The article explains cost-effective approaches of evaluating tooling designs prior to the manufacture of expensive steel dies and dieless forming techniques such as thermal forming and peen forming. It provides information on the application of advanced high-strength steels, magnesium alloys, and various ultrafine-grain materials for superplastic sheet forming. The article concludes with information on the development and application of simulation, design, and control of sheet-forming processes.

This article discusses the sequence of operations for producing a foam pattern for casting. It provides information on expandable polystyrene, the most preferred material for manufacturing lost foam patterns. The article then describes the major functions of pattern molding and assembly. The types and application methods of various lost foam coatings are explained. The article also describes the investment of the foam pattern in a sand system. It concludes with a discussion on the advantages of lost foam casting and information on the formation and control of folds.

In-process inspection during composite material lay-up is essential if the structural, dimensional, and environmental performance designed into a part is to be consistently achieved. This article discusses the requirements to be met by the facilities and equipment to produce high-quality composites. It reviews the procedures that are allowed and prohibited in controlled-contamination areas of lay-up. The article emphasizes significant areas, such as material control and lay-up process, in which quality-control personnel can be effective in preventing production problems. It concludes with a discussion on automated tape laying and fiber placement, as well as the numerically aided lay-up process.

Surface hardening improves the wear resistance of steel parts. This article focuses exclusively on the methods that involve surface and subsurface modification without any intentional buildup or increase in part dimensions. These include diffusion methods, such as carburizing, nitriding, carbonitriding, and austenitic and ferritic nitrocarburizing, as well as selective-hardening methods, such as laser transformation hardening, electron beam hardening, ion implantation, selective carburizing, and surface hardening with arc lamps. The article also discusses the factors affecting the choice of these surface-hardening methods.

This article describes the unique aspects of cold isostatic pressing (CIP) in comparison with die compaction, for powder metallurgy parts. It details the components of CIP equipment, including pressure vessels, pressure generators, and tooling material. The article reviews the part shapes and their influence in determining tap density of the filled mold. It provides a discussion on process parameters, such as dwell time, depressurization rate, evaluation of green strength and density, and thermal processing, and illustrates a process flowchart for the production of CIP parts.