This article addresses dies and die materials used for hot forging in vertical presses, hammers, and horizontal forging machines (upsetters). It reviews the properties of die materials for hot forging, including good hardenability, resistance to wear, plastic deformation, thermal fatigue, and mechanical fatigue. The article describes heat treating practices commonly employed for chromium- and tungsten-base AISI hot-work tool steels. It discusses the fabrication of impression dies, and the advantages and disadvantages of cast dies. The article concludes with a discussion on the factors that affect die life and safety precautions to be considered during die construction.

This article describes two rapid tooling technologies, namely, direct rapid tooling and indirect rapid tooling, for forging-die applications. Commonly used direct rapid tooling technologies include selective laser sintering, three-dimensional printing, and laser-engineered net shape process. The indirect rapid tooling technologies include 3D Keltool process, hot isostatic pressing, rapid solidification process tooling, precision spray forming, and radially constricted consolidation process.

Forging machines use a wide variety of hammers, presses, and dies to produce products with the desired shape, size, and geometry. This article discusses the major types of hammers (gravity-drop, power-drop, high speed, and open-die forging), and presses (mechanical, hydraulic, screw-type, and multiple-ram). It further discusses the technologies used in the design of dies, terminology, and materials selection for dies for the most common hot-forging processes, particularly those using vertical presses, hammers, and horizontal forging machines. A brief section is included on computer-aided design in the forging industry. Additionally, the article reviews specific characteristics, process limitations, advantages, and disadvantages of the most common forging processes, namely hot upset forging, roll forging, radial forging, rotary forging, isothermal and hot-die forging, precision forging, and cold forging.

The properties of irons and steels are linked to the chemical composition, processing path, and resulting microstructure of the material. For a particular iron and steel composition, most properties depend on microstructure. Processing is a means to develop and control microstructure, for example, hot rolling, quenching, and so forth. This article describes the role of these factors in both theoretical and practical terms, with particular focus on the role of microstructure. It lists the mechanical properties of selected steels in various heat-treated or cold-worked conditions. In steels and cast irons, the microstructural constituents have the names ferrite, pearlite, bainite, martensite, cementite, and austenite. The article presents four examples that have very different microstructures: the structural steel has a ferrite plus pearlite microstructure; the rail steel has a fully pearlitic microstructure; the machine housing has a ferrite plus pearlite matrix with graphite flakes; and the jaw crusher microstructure contains martensite and cementite.

Thread rolling is a cold-forming process for producing threads or other helical or annular forms by rolling the impression of hardened steel dies into the surface of a cylindrical or conical blank. Methods that use cylindrical dies are classified as radial infeed, tangential feed, through feed, planetary, and internal. This article focuses on the capabilities, limitations, and machines used for these methods. It describes the three characteristics, such as rollability, flaking, and seaming, used in evaluating and selecting metals for thread rolling. The article explores the factors affecting die life and explains the effect of thread form on processing. It provides information on various fluids used in thread rolling to cool the dies and the work and to improve the finish on the rolled products. The article provides a comparison between thread rolling and cutting, as well as between thread rolling and grinding.

Rotary swaging is an incremental metalworking process for reducing the cross-sectional area or otherwise changing the shape of bars, tubes, or wires by repeated radial blows with two or more dies. This article discusses the applicability of swaging and metal flow during swaging. It describes the types of rotary swaging machines, auxiliary tools, and swaging dies used for rotary swaging and the procedure for determining the side clearance in swaging dies. The article presents an overview of automated swaging machines and tube swaging, with and without a mandrel. It analyzes the effect of reduction, feed rate, die taper angle, surface contaminants, lubrication, and material response on swaging operation. The article discusses the applications for which swaging is the best method for producing a given shape, and compares swaging with alternative processes. It concludes with a discussion on special applications of swagging.

This article is a pictorial guide to forms of corrosion that draws attention to common pitfalls or situations that have caused premature corrosion, sometimes with expensive consequences. The examples used are not exhaustive; they highlight the necessity to fully examine materials, conditions, and specific circumstances that together can reduce the anticipated service life of a component or plant. The color images in this article are categorized according to the type of corrosion following the general order that is adopted in Volume 13A of ASM Handbook. The first table of the article provides a categorization of the forms of corrosion. It also provides a reference to articles or sections of articles in Volume 13A that detail the particular corrosion form or mechanism. The second table is a guide listing the figures in this article by material and by the corrosion form or mechanism illustrated.

Open-die forging can be distinguished from most other types of deformation processes in that it provides discontinuous material flow as opposed to continuous flow. This article describes the equipment and auxiliary tools used in open-die forging. It discusses the production and practice of open-die forging, with some practical examples. The article illustrates macrosegregation in a large steel ingot and lists the forgeable alloys. It reviews the physical and mathematical models used in deformation modeling. The article explains the contour forging and roll planishing process. It inform that to ensure that forgings can be machined to correct final measurements, it is necessary to establish allowances, tolerances, and specifications for flatness and concentricity. The article also tabulates the allowances and tolerances for as-forged shafts and bars.

Electroless nickel plating is used to deposit nickel without the use of an electric current. This article provides an overview of the solution composition and characteristics of the electroless nickel bath. It focuses on the metallurgical, mechanical and physical properties of electroless nickel-phosphorus coatings and electroless nickel-boron coatings. The effect of electroless nickel coatings on the fatigue strength of steel is also described. The article includes information on the recommended pretreatment procedures for different ferrous alloys, aluminum alloys, and copper alloys. It presents a detailed account of the equipment and various processes—including bulk and barrel plating—involved in electroless nickel plating, and discusses hydrogen relief methods. The article includes a comprehensive table on nickel plating applications, and concludes with information on electroless nickel coatings on composites and plastics.

Pickling is the most common of several processes used to remove scale from steel surfaces. This article provides a discussion on pickling solutions, such as sulfuric and hydrochloric acid, and describes the role of inhibitors in acid pickling. It discusses the equipment and processes involved in the batch, continuous, and electrolytic pickling of carbon steel components. The article describes the effects of process variables on scale removal in sulfuric and hydrochloric acid. It concludes with a description of pickling defects, spent pickle liquor disposal, and safety practices.

The heat treatment of steel involves a number of processes (such as stress relieving, normalizing, annealing etc) to condition the microstructure and obtain desired properties. This article discusses typical heat treating process control procedures for carbon and low-alloy steels, as well as the importance of time, and temperature control in heat treatment. Temperature Uniformity Survey, a testing procedure intended to map variations in temperature throughout the furnace work zone, helps in precise control of temperature. The article focuses on the measuring instruments used to determine gas pressure, vacuum level, gas flow, and gas composition. It focuses on their measuring quenchant characteristics, including bulk temperature, viscosity, composition, and cooling efficiency. The article describes the procedures for detecting variability in the incoming product. It presents, through an example, the general application of design of experiments techniques to locate and tune vital process parameters. The devices used in the control process of mechanical components are also reviewed.

This article focuses on the types, composition, and applications of phosphate coatings and describes the characteristics of phosphate-coated ferrous and nonferrous materials, including steel and aluminum. It addresses five successive process fundamentals: cleaning, rinsing, phosphating, rinsing after phosphating, and chromic acid rinsing. The article describes the techniques for controlling the chemical composition of various phosphating solutions. It discusses the equipment and factors that influence equipment requirements in immersion and spray systems. The article also describes the controlling procedures of coating weight and crystal size. It provides guidelines for choosing phosphate coatings based on application, coating weight requirements, and recommended process parameters. The article concludes with a discussion on safety precautions and the treatment of effluents from phosphating plants.

This article describes die wear and failure mechanisms, including thermal fatigue, abrasive wear, and plastic deformation. It summarizes the important attributes required for dies and the properties of the various die materials that make them suitable for particular applications. Recommendations on the selection of the materials for hot forging, hot extrusion, cold heading, and cold extrusion are presented. The article discusses the methods of characterizing abrasive wear and factors affecting abrasive wear. It discusses various die coatings and surface treatments used to extend the lives of dies: alloying surface treatments, micropeening, and electroplating.

Radial forging is a hot- or cold-forming process that uses two or more radially moving anvils or dies to produce solid or tubular components with constant or varying cross sections along their lengths. This article focuses on the workpiece configuration, workpiece materials, machines, dies, advantages, and limitations of radial forging. It concludes with a discussion on the applications of radial forging.

This article provides an overview of the capabilities of closed-die forging. One of the most important aspects of closed-die forging is proper design of preforming operations and of blocker dies to achieve adequate metal distribution. The article describes the effects of friction and lubrication in forging. It discusses the types of closed-die forgings, namely, blocker-type, conventional, and close-tolerance. The article illustrates the classification of forging shapes and explains how to predict the forging pressure and the control of die temperature during closed-die forging. It explains the use of heating equipment for closed-die forging and tabulates the maximum safe forging temperatures for carbon and alloy steels. The article concludes with a discussion on a trimming method used for closed-die forgings.

Cold heading is typically a high-speed process where a blank is progressively moved through a multi-station machine. This article discusses various cold heading process parameters, such as upset length ratio, upset diameter ratio, upset strain, and process sequence design. It describes the various components of a cold-heading machine and the tools used in the cold heading process. These include headers, transfer headers, bolt makers, nut formers, and parts formers. The article explains the operations required for preparing stock for cold heading, including heat treating, drawing to size, machining, descaling, cutting to length, and lubricating. It lists the advantages of the cold heading over machining. Materials selection criteria for dies and punches in cold heading are also described. The article provides examples that demonstrate tolerance capabilities and show dimensional variations obtained in production runs of specific cold-headed products. It concludes with a discussion on the applications of warm heading.

This article reviews the methods of machining and finishing forging dies. It illustrates different stages in die manufacturing. The article provides a brief description on requirements and characteristics of high-speed machining tools, including feed rates, spindle speed, surface cutting speeds, and high acceleration and deceleration capabilities. It discusses electrodischarge machining process and electrochemical machining process. The article concludes with information on die-making methods.

Hot extrusion is a process in which wrought parts are formed by forcing a heated billet through a shaped die opening. This article discusses nonlubricated and lubricated hot extrusion. The two nonlubricated hot extrusion methods are forward or direct extrusion and backward or indirect extrusion. The article illustrates the significance of extrusion speeds and temperatures in hot extrusion. It describes the basic types of presses used in the hot extrusion of metals. The article provides information on the characterization of extruded shapes and explains the operating parameters, including extrusion velocity, amount of pressure required, and type of lubricant, for successful and efficient hot extrusion. The article concludes with a discussion on applications and design methodology that provides insight into CAD/CAM of extrusion dies.

This article discusses the operation of upset forging machines and selection of the machine size. It describes several types of upsetter heading tools and their materials. The article reviews the cold shearing and hot shearing methods for preparing blanks for hot upset forging. It deals with various upsetting processes: offset upsetting, double-end upsetting, upsetting with sliding dies, upsetting pipe and tubing, and electric upsetting. The article also provides information on hot forging and cold forging.

This article provides a summary of the overall development of the finite element method (FEM) and its contribution to the materials forming industry. It presents an overview of FEM methodologies and applications in the order of their usage in typical manufacturing (bulk forming process) process sequence: primary materials processing, hot forging and cold forming, and product assembly. The article discusses the material fracture and dies stress analysis and presents the optimization techniques used in 2-D and 3-D preform die design.