Titanium and its alloys have been used extensively in a wide variety of implant applications, such as artificial heart pumps, pacemaker cases, heart valve parts, and load-bearing bone or hip joint replacements or bone splints. This article discusses the properties of titanium and its alloys and presents titanium-base biomaterials in a table. Titanium components are produced in wrought, cast, and powder metallurgy (PM) form. The article describes forging, casting, and heat treating of titanium alloys for producing titanium components. Typical mechanical properties of titanium biomedical implant alloys are listed in a tabular form. The article presents an overview of surface-modification methods for titanium and its alloys implants. It concludes with a section on biocompatibility and in vivo corrosion of titanium alloys.

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.

The distinction between an unconfined web and a confined web describes the relative ease of flow of metal to flash during forging. This article describes the various types of unconfined and confined web-and-rib combinations encountered in the design of forgings. It informs that the limits suggested by forging producers and users covering minimum web thicknesses that are producible are helpful in estimating the producibility of a given web thickness in projected-forging design. The article briefly analyzes the web designs of several forgings, including designs for producing flat webs, contoured webs, and oblique webs. It provides a checklist to be reviewed by a web designer.

This article discusses the forging processes and equipment and forging practice associated with the forging of magnesium alloys. It describes the workability of magnesium alloys. The article concludes with a discussion on the inspection of magnesium alloy forgings.

Forging of nickel-base alloys results in geometries that reduce the amount of machining to obtain final component shapes and involves deformation processing to refine the grain structure of components or mill products. This article discusses the heating practice, die materials, and lubricants used in nickel-base alloys forging. It describes two major forging processing categories for nickel-base alloys: primary working and secondary working categories. Primary working involves the deformation processing and conversion of cast ingot or similar bulk material into a controlled microstructure mill product, such as billets or bars, and secondary working refers to further forging of mill product into final component configurations.

Roll forging is a process for simultaneously reducing the cross-sectional area and changing the shape of heated bars, billets, or plates. This article provides an overview of the process capabilities, production techniques, machines and machine size selection considerations, and types of roll dies and auxiliary tools for the roll forging. It concludes with information on the production examples of roll forging.

Powder forging is an extension of the conventional press and sinter powder metallurgy process, which is recognized as an effective technology for producing a variety of parts to net or near-net shape. This article focuses on the material considerations, such as powder characteristics, alloy development, and inclusion assessment; and process considerations, such as process stages, tool design, and secondary operations; of ferrous alloy powder forging. The mechanical properties of powder forged materials are also reviewed. The article discusses the quality assurance tests for powder forged materials: the part dimensions and surface finish measurement, magnetic particle inspection, metallographic analysis, and nondestructive testing. It concludes with a discussion on the applications of powder forged parts with examples.

Workability in forging depends on a variety of material, process-variable, and die-design features. A number of test techniques have been developed for gaging forgeability depending on alloy type, microstructure, die geometry, and process variables. This article summarizes some common workability tests and illustrates their application in practical forging situations. Workability tests for open-die forging of cast structures, hot and cold open-die forging of recrystallized structures, fracture-controlled defect formation, establishing effects of process variables and secondary tensile stresses on forgeability, and flow-localization-controlled failure are some common tests. The workability test used for closed-die forging is also summarized.

Corners and fillets are curved connecting surfaces on closed-die forgings that unite smoothly the converging or intersecting sides of forged elements, such as ribs, bosses, and webs. This article discusses the effects of several variables, including rib height, type of forging process, composition of the forging alloy, and factors associated with die filling and producibility, on vertical and horizontal corners and fillets. It reviews the design of corners and fillets to satisfy the requirements of metal flow in forging and cost considerations arising from usage and removal of metal by machining. The article presents a graphical summary of the interdependence of corner and fillet dimensions with the dimensions of adjoining ribs and webs. It concludes with information on designer's checklist for corners and fillets.

Hammers and high-energy-rate forging machines are classified as energy-restricted machines as they deform the workpiece by the kinetic energy of the hammer ram. This article provides information on gravity-drop hammers, power-drop hammers, die forger hammers, counterblow hammers, and computer-controlled hammers. It describes the three basic designs of high-energy-rate forging (HERF) machines: the ram and inner frame, two-ram, and controlled energy flow. The article reviews forging mechanical presses, hydraulic presses, drive presses, screw presses, and multiple-ram presses.

Machining serves as a more specialized supplement to the forging process, particularly in the formation of cavities and holes. This article provides information on the enclosures, cavities, and holes in hammer and press forgings. It provides a checklist that serves as a guide to the procedure for reviewing the design of cavities and holes to be incorporated in forgings. The article also describes forging designs in which cavities and holes are related to rib and web designs, punchout, piercing, extruding, and combinations of these processes.

Titanium alloys are forged into a variety of shapes and types of forgings, with a broad range of final part forging design criteria based on the intended end-product application. This article begins with a discussion on the classes of titanium alloys, their forgeability, and factors affecting forgeability. It describes the forging techniques, equipment, and common processing elements associated with titanium alloy forging. The processing elements include the preparation of forging stock, preheating of the stock, die heating, lubrication, forging process, trimming and repair, cleaning, heat treatment, and inspection. The article presents a discussion on titanium alloy precision forgings and concludes with information on the forging of advanced titanium materials and titanium aluminides.

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 discusses the significant factors in the selection of forging equipment for a particular process. It describes the characteristics of forging hydraulic presses, mechanical presses, screw presses, and hammers. The article discusses the significant characteristics of these machines that comprise all machine design and performance data, which are pertinent to the economic use of the machines, including the characteristics for load and energy, time-related characteristics, and characteristics for accuracy.

This article schematically illustrates the basic types of drafts used in forging design, including outside draft, inside draft, blend draft, natural draft, shift draft, and back draft. The amount of draft, or the draft angle, is designated in degrees and is measured from the axis of a hammer or press stroke. The article illustrates the measurement of draft angle by describing the designs of forgings produced in equipment with vertical and horizontal rams. The use of excessive amounts of draft usually results in an increase in overall cost. The article describes various alternatives for reducing or eliminating draft. It provides a checklist citing major items that should be coordinated with a designer's review of draft.

The design of forging operations; consisting of dies, fixturing, and parts; requires a consistent and unambiguous method for representing critical dimensions and tolerances. This article presents a dimensioning process, based on tooling points and datum planes, with the potential to simplify geometries while minimizing tolerance stack-ups. The method also facilitates inspection liaison between vendors and users because fixturing is easy to duplicate and tooling points are consistent from forging to finish-machined part. The article focuses on the most common dimensional tolerances for closed-die forgings, including finish allowances for machining, length and width tolerances, die-wear tolerance, match tolerances, die-closure or thickness tolerances, straightness and flatness tolerances, radii tolerances, flash-extension tolerances, and surface tolerances. It also contains a convenient summary in the form of a checklist.

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.

Discontinuously reinforced aluminum (DRA) alloy metal-matrix composites (MMCs) represent an advanced aluminum materials concept whereby ceramic particles, or whiskers, are added to aluminum-base alloys through the use of either ingot-melting or casting and/or powder-metallurgy (P/M) techniques. This article begins with a summary of general observations on the forging of discontinuously reinforced composites. It provides information on some of the specific experimental results obtained on various DRA systems, including 2xxx DRA alloys and cast DRA alloys. The article reviews the efforts on the modeling of behavior of specific alloy systems, with a comparison of experimental results to the modeling attempts. It concludes with information on the properties of deformation-processed DRA alloys.

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.