This article describes the joint preparation, fit-up and design of various types of laser beam weld joints: butt joint, lap joint, flange joint, kissing weld, and wire joint. It explains the use of consumables for laser welding and highlights the special laser welding practices of steel, aluminum, and titanium engineering alloys. Laser weld quality and quality assessment are described with summaries of imperfections and how its operations contribute to providing repeatable and reliable laser welds. Relevant laser weld quality specifications are listed.

Laser-beam welding (LBW) is a joining process that produces coalescence of material with the heat obtained from the application of a concentrated coherent light beam impinging upon the surface to be welded. This article describes the steps that must be considered when selecting the LBW process. It reviews the individual process variables that influence procedure development of the LBW process. Joint design and special practices related to LBW are discussed. The article concludes with a discussion on the use of consumables and special welding practices.

Most welding lasers fall into the category of fiber, disc, or direct diode, all of which can be delivered by fiber optic. This article provides a comparison of the energy consumptions and efficiencies of laser beam welding (LBW) with other major welding processes. It discusses the two modes of laser welding: conduction-mode welding and deep-penetration mode welding. The article reviews the factors of process selection and procedure development for laser welding. The factors include power density, interaction time, laser beam power, laser beam diameter, laser beam spatial distribution, absorptivity, traverse speed, laser welding efficiency, and plasma suppression and shielding gas. The article concludes with a discussion on laser cutting, laser roll welding, and hybrid laser welding.

Rotational molding is a simple but unique process that has the capability of producing small to large hollow items with very uniform wall thicknesses. Providing an overview of the operating principles of rotational molding, this article discusses the key selection factors, including function and property requirements for resins and additives; size, shape, design, and cost of molded parts; equipment type and size; and the type of mold to be used. Commonly used molds include cast aluminum, fabricated sheet metal, nickel deposit, machined aluminum, silicone, fiberglass, and prototype molds.

This article focuses on friction stir welding (FSW), where frictional heating and displacement of the plastic material occurs by a rapidly rotating tool traversing the weld joint. Much of the research activity early on pertained to issues related to understanding the process, such as learning about material flow, heat generation, microstructure development, and many other fundamental issues. The article summarizes the results of the research, describing the aspects of how FSW actually accomplishes sound joints in metals without melting them. It discusses the FSW process variations and the practical aspects of heat generation. The article provides information on the effect of welding on material properties and typical alloys in FSW applications. The alloys include 6061 aluminum, 5083 aluminum, 2xxx aluminum, and 7xxx aluminum alloys. The article concludes with a discussion on FSW equipment.

Ultrasonic additive manufacturing (UAM) is a solid-state hybrid manufacturing technique that leverages the principles of ultrasonic welding, mechanized tape layering, and computer numerical control (CNC) machining operations to create three-dimensional metal parts. This article begins with a discussion on the process fundamentals and process parameters of UAM. It then describes metallurgical aspects in UAM. The article provides a detailed description of a wide range of mechanical characterization techniques of UAM, namely tensile testing, peel testing, and pushpin testing. The article ends with information on sensor embedding.

X-ray imaging is a nondestructive evaluation (NDE) technique in which x-ray waves interact with an observed sample to generate images from which information about the examined object can be derived. This article discusses x-ray imaging systems and applications, presenting the history and role of x-ray imaging. It describes different setups that are implemented at various facilities that conduct x-ray imaging for different types of metal AM processes. The article also discusses different types of dynamics observed in experimental metal AM processes using x-ray imaging systems. It presents the future of x-ray imaging in metal AM.

Precision forging is defined as a closed-die forging process in which the accuracy of the shape, dimensional tolerances, and surface finish exceed normal expectations to the extent that some of the postforge operations can be eliminated. This article provides an overview of the key factors that impact the precision forging process. It provides information on the achievable tolerances and presents examples of precision forging. A discussion on forging of bevel gears/spiral bevel gears is also presented.

This article discusses the inspection/reference standards that are absolutely critical for proper application of ultrasonic inspection systems. Many of the standards and specifications for ultrasonic inspection require the use of standard reference blocks. The article lists the variables that should be considered when selecting standard reference blocks and describes the three types of standard blocks ordinarily used for calibration or reference: area-amplitude blocks, distance-amplitude blocks, and blocks of the type sanctioned by the International Institute of Welding. It reviews the determination of area-amplitude and distance-amplitude curves of a straight-beam pulse-echo ultrasonic inspection system. The article discusses the three principal conventional manual ultrasonic sizing techniques: 6 dB drop technique, maximum-amplitude technique, and 20 dB drop technique. It provides information on the dimension-measurement applications of ultrasonic inspection methods.

This article introduces the principal methodologies and some advanced technologies that are being applied for nondestructive evaluation (NDE) of fiber-reinforced polymer-matrix composites. These include acoustic emission, ultrasonic, eddy-current, computed tomography, electromagnetic acoustic transducer, radiography, thermography, and low-frequency vibration methods. The article also provides information on NDE methods commonly used for metal-matrix composites.

This article introduces the principal methodologies and some technologies that are being applied for nondestructive evaluation of composite materials. These include ultrasonic testing (UT), air-coupled UT, laser UT, ultrasonic spectroscopy, leaky lamb wave method, acousto-ultrasonics, radiography, X-ray computed tomography, thermography, low-frequency vibration methods, acoustic emission, eddy current testing, optical holography, and shearography. The article presents some examples are for fiber-reinforced polymer-matrix composites. Many of the techniques have general applicability to other types of composites such as metal-matrix composites and ceramic-matrix composites.

The development of aluminum alloys has progressed along two tracks: heat treatable and non-heat treatable. The Aluminum Association alloy composition limits and product temper are defined for major alloying elements. This article summarizes the historical evolution of the different series of wrought aluminum alloys (1xxx to 8xxx) and discusses their applications based on the alloying system introduced by the Aluminum Association.

This article presents the basic principle, characteristics, advantages, and disadvantages of resonant ultrasound spectroscopy (RUS) methods in additive manufacturing. It focuses on the two types of RUS methods: the swept-sine method and the impulse excitation method. Representative significant results for additively manufactured complex parts obtained with the different RUS systems are also shown. The article also presents the basic principle and examples of nonlinear RUS methods.

X-ray radiography and computed tomography (CT) are nondestructive testing (NDT) tools particularly well suited to additive manufacturing (AM). A brief overview of NDT for AM is presented in this article, including other NDT methods, followed by identifying the key advantages and requirements for x-ray radiography and CT in AM. Less widely known applications of CT are also presented, including powder characterization, the evaluation of lattice structures, surface roughness measurements, and four-dimensional CT involving interrupted (before-after) CT scans of the same parts, or even in situ scans of the same part subjected to some processing or loading conditions. The article concludes with a discussion on the limits and some guidelines for the use of x-ray and CT for various AM materials.

This article discusses the classifications of high-speed tool steels and describes alloying elements and their effects on the properties of high-speed tool steels. It analyzes the heat treatment of high-speed tool steels, namely, preheating, austenitizing, quenching, and tempering. Surface treatments for the high-speed tool steels are reviewed. The article emphasizes the properties and applications of high-speed tool steels and provides information on the factors in selecting high-speed tool steels.

This article discusses the particular corrosion problems encountered and the corrosion control methods used in petroleum production (i.e., upstream) and the storage and transportation of oil and gas (i.e., midstream) up to the refinery (i.e., downstream). These control methods include proper material selection, protective coatings, cathodic protection systems, use of inhibitors, use of nonmetallic materials, and control of the environment. The article reviews the aspects of corrosion that tend to be unique to corrosion as encountered in applications involving oil and gas exploration and production. It discusses corrosion problems that are specific to the various types of environments or equipment used in secondary recovery, including producing wells, producing flow lines, and injection wells. Corrosion mitigation methods and guidelines are also discussed for each type of environment.

This article presents a general understanding of causes and possible solutions for defects in the most common metal additive manufacturing (AM) processes: laser powder-bed fusion (L-PBF), laser directed-energy deposition (DED-L), and binder jetting (BJ).